Chapter 13

Of all the factors involved in growing plants, soil is the most complex. It has its own ecology, which can be modified, enriched, or destroyed; the treatment it receives can ensure crop success or failure.

There is no such thing as the perfect soil for Cannabis. Each variety can grow within a wide range of soil conditions. Your goal is garden soil within the range for healthy growth: well-drained, high in available nutrients, and with a near neutral (7.0) pH. Cannabis grows poorly, if at all, in soils which are extremely compacted, have poor drainage, and low in fertility, or have an extreme pH.

There are several soil factors that are important to a grower; these include soil type, texture, pH, and nutrient content. We will begin this chapter by discussing each of these topics in succession, and will then turn to discussion of fertilisers, soil-preparation techniques, and guerilla farming methods.

Types of Soil

Each soil has its own unique properties. These properties determine how the soil and plants will interact. For our purposes, all soils can be classified as sands, silts, clays, mucks, and loams. Actually, soils are usually a combination of these ingredients. If you look carefully at a handful of soil, you may notice sand granules, pieces of organic matter, bits of clay, and fine silty material.

Sandy Soils

Sands are formed from ground or weathered rocks such as limestone, quartz, granite, and shale. Sandy soils may drain too well. Consequently, they may have trouble holding moisture and nutrients, which leach away with heavy rain or watering. Some sandy soils are fertile because they contain significant amounts (up to two percent of organic matter, which also aids their water-holding capacity. Sandy soils are rich in potassium (K), magnesium (Mg), and trace elements, but are often too low in phosphorous (P) and especially nitrogen (N). N, which is the most soluble of the elements, is quickly leached from sandy soil. Vegetation on sands which is pale, yellowed, stunted, or scrawny indicates low nutrients, usually low N.

Sandy soils can be prepared for cultivation without much trouble. They must be cleared of ground cover and treated with humus, manure, or other N-containing fertilisers. In dry areas, or areas with a low water table, organic matter may be worked into the soil to increase water-holding capacity as well as fertility. Sandy soil does not usually have to be turned or tilled. Roots can penetrate it easily, and only the planting row need be hoed immediately before planting. Growers can fertilise with water-soluble mixes and treat sandy soil almost like a hydroponic medium.

Sandy soils are also good candidates for a system of sheet composting (spreading layers of uncomposted vegetative matter over the garden), which allows nutrients to gradually leach into the soil layers. Sheet composting also prevents evaporation of soil water, since it functions as a mulch.


Silts are soils composed of minerals (usually quartz) and fine organic particles. To the casual eye, they look like a mucky clay when wet, and resemble dark sand or brittle clods when dry. They are the result of alluvial flooding, that is, are deposits from flooding rivers and lakes. Alluvial soils are usually found in the Midwest, in valleys, and along river plains. The Mississippi Delta is a fertile alluvial plain.

Silts hold moisture but drain well, are easy to work when moist, and are considered among the most fertile soils. They are frequently irrigated to extend the length of the growing season. Unless they have been depleted by faulty farming techniques, silts are rich in most nutrients. They often support healthy, vigorous vegetation. This indicates a good supply of N.


Mucks are formed in areas with ample rainfall which supports dense vegetation. They are often very fertile, but may be quite acidic. They usually contain little potassium.

Mucks range from very dense to light sandy soils. The denser ones may need heavy tilling to ensure healthy root development, but the lighter ones may be cleared and planted in mounds. Mucks can support dense vegetation, and are often turned over so that the weeds thus destroyed form a green manure.

Clay Soils

Clays are composed of fine crystalline particles which have been formed by chemical reactions between minerals. Clays are sticky when wet, and can be moulded or shaped. When dry, they form hard clods or a pattern of square cracks along the surface of the ground. Clays are usually hard to work and drain poorly. Marijuana roots have a hard time penetrating clay soils unless these soils are well-tilled to loosen them up. Additions of perlite, sand, compost, gypsum, manure, and fresh clippings help to keep the soil loose. Clay soils in low-lying areas, such as stream banks, may retain too much water, which will make the plants susceptible to root and stem rots. To prevent this, some growers construct mounds about six inches to one foot high, so that the stems and tap roots remain relatively dry.

Clay soils are often very fertile. How well marijuana does in clay soils usually depends on how well these soils drain. In certain areas "clay" soils regularly support corn cotton. This type of soil will support a good crop of marijuana. Red colour in clay soil (red dirt) indicates good aeration and a "loose" soil that drains well. Blue or gray clays have poor aeration and must be loosened in order to support healthy growth.

A typical schedule for preparing a heavy clay soil In the late fall, before frost, turn soil, adding fresh soil conditioners, such as leaves, grass clippings, fresh manure, or tankage. Gypsum may also be added to loosen the soil. Spread a ground cover, such as clover, vetch, or rye. In early spring, making sure to break up the large clods, and add composts and sand if needed. At planting time, till with a hoe where the seeds are to be planted.

As the composts and green manure raise the organic level in the soil, it becomes less dense. Each year, the soil is easier to work and easier for the roots to penetrate. After a few years, you may find that you only need to turn under the cover crop. No other tilling will be needed.


Loams are a combination of about 40 percent each of sand and silt, and about 20 percent clay. Organic loams have at least 20 percent organic matter. In actuality, a soil is almost always a combination of these components, and is described in terms of that combination, e.g., sandy silt, silty clay, sandy clay, or organic silty clay. Loams range from easily worked fertile soils to densely packed sod. Loams with large amounts of organic matter can support a good marijuana crop with little modification.

Humus and Composts

Humus and composts are composed of decayed organic matter, such as plants, animal droppings, and microbes. Their nutrient contents vary according to their original ingredients, but they most certainly contain fungi and other microorganisms, insects, worms, and other life forms essential for the full conversion of nutrients. As part of their life processes, these organisms take insoluble chemicals and convert them to soluble forms, which plant roots can then absorb. Humus and composts hold water well and are often added to condition the soil. This conditioning results from the aerating properties and water-holding capacity of humus and composts, as well as balanced fertility.

Humus and composts have a rich, earthy small, look dark brown to black, and may contain partially decayed matter, such as twigs or leaves. They are produced naturally as part of the soil's life process or can be "manufactured" at the site by gathering native vegetation into piles. Composts cure in one to three months, depending on both ingredients and conditions. Decomposition can be speeded up by turning and adding substances high in N. Composts are frequently acidic and are sweetened with lime when they are piled. This also shortens curing time, since the desirable microbes prefer a neutral medium.


Soil texture refers to density, particle size, and stickiness, all of which affect the soil's drainage and water-holding characteristics. The most important quality of the soil for marijuana is that it drains well - that is, water does not stand in pools after a rain, and the soil is not constantly wet. In a well-drained soil, the roots are in contact with air as well as water.

Cannabis does best on medium-textured soils: soils that drain well, but can hold adequate water. Loams, silts, and sands usually drain well and are loose enough to permit good root development. Some clays and most mucks are too compact to permit the lateral roots to penetrate and grow. In addition, they often drain poorly, and when dry they may form hard crusts or clods, a condition marijuana cannot tolerate.

Several simple tests will indicate the consistency and drainage qualities of your soil. Test when the soil is moist but not wet. First, dig a hole three feet deep to check the soil profile. In a typical non-desert soil, you will find a layer of decaying matter on the surface, which evolves into a layer of topsoil. Most of the nutrients available to the plant are found at this level or are leached down from it. The topsoil layer is usually the darkest. It may only be an inch thick or may extend several feet. When in good condition, the topsoil is filled with life. Healthy topsoil contains abundant worms, bugs, and other little animals, and is interlaced with roots. If you can easily penetrate the underlying topsoil with your hands, its texture is light enough for healthy root growth.

The next layer, or subsoil, may be composed of a combination os sand, clay, and small rocks, or you may hit bedrock. Sandy, rocky, and loamy subsoils present no problems as long as the topsoil is at least six inches thick. Clay or bedrock often indicates drainage problems, especially if the spot has a high water table and stays wet.

Next scrape up a handful of soil from each layer. Press each handful in your fist, release it, and poke the clump with a finger. If it breaks apart easily, it is sandy or loamy. Clods that stick together, dent, or feel sticky indicate clay or muck.

To test for drainage, fill the hole with water. Wait half an hour to let the moisture penetrate the surrounding soil; then fill the hole with water again. If the water drains right through, you are working with sandy soil. If it doesn't drain completely within 24 hours, the soil has poor drainage.


The pH is a measure of how alkaline (bitter) or acid (sour) the soil is. The pH balance affects the solubility of nutrients, and helps the plant regulate metabolism and nutrient uptake. The scale for measuring pH runs from 0 to 14, with 7 assigned as neutral. A pH below 7 is acid; a pH above 7 is alkaline.

Marijuana grows in soils with a pH range from 5 to 8.5, but it thrives in nearly neutral soils. Relative to other field crops, it has high lime requirements, similar to those for red or white clover or sunflower. But it does well in fields where plants with medium lime requirements, such as corn, wheat, and peanuts, are grown.

The solubility of nutrients is affected by soil type as well as by the pH. In soils with a high content of organic matter, all nutrients are soluble between 5.0 and 6.5. Phosphorous, manganese, and boron are less soluble at pH values above 6.5. Acid soils are usually found in the United States east of the 100th meridian and along parts of the West Coast, and a deep topsoil layer. Marijuana does best in acid soils when the pH is adjusted to a range of 6.3 to 7.0. {Figure 58. Map of pH for US.}

Mineral soils in the dry western states may be slightly acid to highly alkaline. Most nutrients are very soluble in these soils, as long as the pH ranges from 6.0 to 7.5. Some of these soils are too alkaline (over 8.5); so their pH must be adjusted to near neutral to ensure healthy growth.

Adjusting the pH

First test the soil pH in the garden area. Previous gardeners may have adjusted native soils, or your yard soil may have been trucked in to cover poor native soils, so that the pH of your garden soil may be different from that of other soils in the area. Different soils vary in the amount of material needed to adjust the pH. Sandy soils do not require as much as loam, and loam requires less than clays, partly because of the chemistry, and partly because of the density and physical qualities of the soils' particles.

Adjusting Acid Soils

Acidic soils are treated with limestone, which is expressed as an equivalent of calcium carbonate (CaCO3). Limestone is usually quarried and powdered, contains large amounts of trace elements, and comes in different chemical forms: ground limestone, quicklime, and hydrated lime (which is the fastest acting form). Dolomitic limestone is high in magnesium and is often used to adjust magnesium-deficient soils, such as those found in New England. Marl (ground seashells) is also mostly lime and is used to raise soil pH. Eggshells are another source of lime. They should be powdered as finely as possible, but even so, they take a long time to affect the soil. Wood ashes are alkaline and very soluble; so they have an almost immediate effect.

Every commercial lime has a calcium carbonate equivalent or neutralising power which is listed on the package. To find out how much to use, divide the total amount of limestone required by the pH test (see Figure 59) by the calcium carbonate equivalent. For instance, a field requires fifty pounds of limestone, but the calcic limestone you are using has an equivalent of 1.78. Divide the 50 by 1.78. The resulting figure, about 29 pounds, is the amount required. Commercial limes also list the grade or particle size of the powder. In order of fineness they are: superfine, pulverised, agricultural grade, and fine meal. The finer the grade, the faster the action. {Figure 59. Approximate amount of lime required to adjust pH of a 7" layer of different types of soil.}

For best results, lime should be added at least four or five months before planting. In this way, the lime has a chance to react with the soil. But acid soils can be limed profitably and time before planting, or after, as long as the lime does not come into direct contact with the plants. Most growers add lime at the same time that they fertilise and turn the soil. That way, tilling and conditioning are handled in one operation. The lime should be worked into the soil to a depth of ten inches. Lime can also be added by spreading it before a rain. Make sure that the soil is moist enough to absorb the rain, so that the lime does not run off. Growers who have not adjusted the pH can dissolve lime in water before they irrigate. However, this is not advised if the water runs through a hose or pump, because mineral buildup may occur in the equipment.

Adjusting Alkaline Soils

Most alkaline soils have a pH no higher than 7.5, which is within the range for optimum growth. Soils that are too alkaline can be adjusted by adding gypsum, which frees insoluble salts, and include iron, magnesium, and aluminium sulphate. Marijuana has a low tolerance for aluminium; so marijuana growers should use iron or magnesium sulphate in preference to aluminium sulphate. Sulphur and gypsum are worked into the soil in the same manner as lime.

{Table 19.}

Some growers correct alkaline soils by adding an organic mulch or by working acidic material into the soil. Cottonseed meal, which is acidic and high in nitrogen, can also be used. As it breaks down, cottonseed meal neutralises the soil. Pine needles, citrus rinds, and coffee grounds are all very acidic, and can be used to correct alkaline conditions. The addition of soluble nitrogen fertilisers aids the breakdown of these low-nitrogen additives. (See Table 22 in the section on "Fertilisers" in this section.)

Adjusting Alkali Soils

Alkali soils (pH usually above 8.5) are hardpacked and crusty, and sometimes have an accumulation of white powdery salts at the surface. They may not absorb water easily and can be extremely difficult to work. To prepare alkali soils with a permeable subsurface for cultivation, farmers leach them of their toxic accumulation of salts. The soils is thoroughly moistened so that it absorbs water. Then it is flooded so that the salts travel downward out of contact with the roots. Gypsum can be added to free some of the salts so that they leach out more easily. Gypsum can be added at the rate of 75 lbs per 100 sq.ft., or 18 tons per acre. Leaching requires enormous quantities of water, an efficient irrigation system, and several months.

{Plate 1. Skylights are a good source of bright, unobstructed light. Thai plant (closest) and Colombian plants reached over 14 feet in six months.

Plate 2. Top: A hidden garden using fluorescent light, foil reflectors, and bag containers. Plants are ten weeks old. Bottom: Simple to construct dome greenhouse in southern California. At two months, some of these plants are six feet tall.

Plate 3. Upper left: Stem of a female plant. Upper right: In full sunlight, a pruned plant can grow incredibly dense. Bottom: A garden in the wilds of Oregon mountains.

Plate 4. Marijuana does well in most gardens. Top: Here a female plant is in early bloom at five months. The main stem was clipped at three months (Berkeley). Middle: Lower branches are spread out to catch the sun. Bottom: A female bud about two weeks before harvest. Leaves show some damage from leafhoppers (insects shown).

Plate 5. A giant sinsemilla cola grown from Mexican seed in northern California.

Plate 6. Top: Purple colours often appear late in life, when vigour is waning. Lower left: Resin glands glistening on a purple, female flowering shoot. Lower right: Yellow male flowers and purple leaves against a normal green leaf.

Plate 7. Top: Male flowers at different stages in development. A line of resin glands can be seen on the anthers of the open flowers. Lower left: Resin glands lining the pollen slit of an anther (x40). Middle right: Male flowers in full bloom. The leaves are covered with fallen pollen. Lower right: Gland heads may fall with the pollen grains. Mature grains are spherical in field of focus (x40).

Plate 8. Top: Resin glands on the lower (adaxial) surface of a small, fresh leaf blade. Integrals are one millimetre (x16). Middle and lower left: Stalked glands are concentrated along the veins of the lower leaf surface (x40). Lower right (x100).

Plate 9. Top: Upper (adaxial) fresh leaf surface. Left of picture, from left to right: Sharp-pointed cystolith hair, stalked gland, and tiny bulbous gland (x40). Lower left: Upper surface of a Thai leaf (x16). Lower right: Upper surface of fresh homegrown Colombian leaf (x40).

Plate 10. A young female flower (homegrown Colombian). Resin glands are not yet fully developed (x16).

Plate 11. Top left: A mature female flower from the same plant is in Plate 10. The flower bract is swollen from the ripe seed it contains. Notice the well-developed resin glands (x25). Top right: A mixture of seeds from common marijuana varieties shows comparative size. Bottom: The tip of a sinsemilla flower at harvest. Notice cream-coloured stigmas to the left and the fresh, clear resin glands (x40).

Plate 12. Upper and lower left: An overly ripe sinsemilla flower bract. Many gland heads are brown or missing (top, x16; bottom, x40). Upper and lower right: Carefully handled Thai weed with intact glands. Notice the high concentration of glands and very long stalks on this bract (top, x16; bottom, x40).

Plate 13. Upper and lower left: A Colombian gold. Gland contents are brown and stalks have deteriorated on this bract (top, x16; bottom, x40). Top right: Hawaiian; well-handled and showing little deterioration (bract x40). Middle right: Gland heads easily detach from stalks when overripe (leaf vein x40). Lower right: Stalked glands on both upper and lower leaf surfaces beginning to brown (leaf margin x40).

Plate 14. Top: Whitefly larvae and their honeydew excretions on the lower surface of a leaf. Middle left: Leaf showing whitefly damage and a tiny adult. Lower left: White speckles on leaves indicating mite damage. Lower right: An overdose, or overuse of pesticide, can kill the plant.

Plate 15. Upper left: Healthy green plant next to a N-deficient plant. Middle left: Ultraviolet burn. Plant was moved outdoors without conditioning. Lower left: "Bonsai" marijuana grown from a cutting. Upper right: Mg-deficient plant has chlorotic leaves dying from their tips. Lower right: Afghani variety, with characteristically wide leaf blades, show minor symptoms of N deficiency (pale leaves and red petioles).

Plate 16. Upper left: Male flowers lose some green and turn "blond" during slow drying. Upper right: Cigar joints made with undried marijuana, which is wrapped with lone blades of fan leaves before drying. Bottom: Sequence shows change in colour in one day from sun curing.{Unfortunately, all the plates are in black and white.}}

Another method of reclaiming alkali soils is by adding a thick mulch and letting it interact with the soil during the winter. The mulch should be about nine inches thick, or 130 lbs or more per 100 sq.ft. This thick layer neutralises the salts and also helps to retain moisture.


Marijuana is a high-energy plant which grows quickly to its full potential in a fertile soil that is rich in available nutrients. Nutrients are found in the soil's parent materials: sand, clay, humus, minerals, rocks, and water. Nutrients dissolve in soil water (soil solution), which is then absorbed by the plant. In complex chemical processes, roots release ions in exchange for nutrients that are dissolved in the soil solution.

The soil acts as a reservoir for the nutrients. Most of them are in non-exchangeable forms: that is, they do not dissolve, or dissolve only slightly in water. Only a small percentage of the total reserve is free at any time as the result of chemical processes or microbial action. Healthy soils maintain a balance between free and unavailable nutrients, so that the plants they support continually receive the right amounts of required nutrients. Alkali soils have large supplies of compounds which are extremely soluble. The solution is so concentrated that alkali soils are often toxic to plants.

There are three primary nutrients, N (nitrogen), P (phosphorus), and K (potassium). These are the nutrients that gardeners are most likely to be concerned with and which most fertilisers supply. Soils are most likely to be deficient in one of these nutrients, especially N.

In addition to the primary nutrients, soil supplies plants with three secondary nutrients, Ca (calcium), Mg (magnesium), and S (sulfur), and seven micronutrients: iron, boron, chlorine, manganese, copper, zinc, and molybdenum. Although deficiencies of all the secondary and micronutrients are reported from various parts of the United States, serious deficiencies do not occur often. ((For a discussion of the symptoms of nutrient deficiencies is marijuana, see section 9.))

Marijuana absorbs nutrients primarily through a fine network of lateral roots which grow from the taproot. Lateral roots may spread over an area with a diameter of five feet, and may go as deep as the roots can penetrate. Plants in deep sandy soils or in soils that have porous mineral subsoils may grow roots as deep as even seven feet. Roots which can absorb nutrients from a larger area are more likely to fulfil the plants' needs than are shallow roots which result in shallow topsoil layers over compacted subsoils. When the roots have a large area from which to absorb nutrients, the soil does not need to be as fertile as when the roots are restricted to a small area by poor soil or by being grown in pots.

You can get a good indication of soil fertility by observing the vegetation that the soil supports. If the vegetation is varied, has a lush look to it, is deep green, and looks vigorous, it is probably well-supplied with nutrients. If the plants look pale, yellowed, spindly, weak, or generally unhealthy, the soil is probably deficient in one or more nutrients.


Agricultural colleges, County Extension Agents, and private companies perform soil analyses for a small fee from a sample you mail to them. The tests include nutrient, pH, and texture analyses, and are very accurate. There are also simple-to-use test kits available at nurseries and garden shops which give a fair indication of soil fertility and pH. Test results include a suggested fertiliser and lime program catered to the soil's individual requirements for the crop to be planted. Marijuana has nutrient requirements similar to those for corn, wheat, and sugarcane, and prefers just a little more lime (a more alkaline soil) than those crops; so soil can be fertilised as it would be for those crops.

Soil tests are one indication of soil fertility. They test for available nutrients, but not for reserves that are held in the soil. Test results may also vary because of recent rainfall, changes of moisture content, and seasonal changes. Most soil tests do not measure the ability of the soil to make nutrients available. This is a very important factor when considering a fertiliser program and should not be overlooked. As an example, an uncultivated field showed only moderate amounts of N available, and indicated a need for N fertiliser. The vegetation - tall grass, weeds, and bush - had a healthy look and was dark green, and the lower leaves remained healthy. Obviously, the soil was able to supply an adequate amount of N to the plants, which withdrew it from the soil solution as it became available. The soil and plants had reached a balance, and the soil solution slowly became more dilute over the course of the season.

To a great extent, the soil's ability to maintain a constant and adequate supply of nutrients depends on the soil's humus content. Humus can support dense populations of microorganisms. As part of their life processes, microorganisms decompose organic matter in the humus. Nutrients contained in the organic matter are released by microbes as simply inorganic molecules (e.g., NO3) which can dissolve in soil water. Generally, soils with a high humus content can keep plants supplied with more nutrients than soil tests indicate.

The Primary Nutrients

If you look at any fertiliser package, you will note three numbers on the package. They stand for N-P-K, always in that order. Marijuana does best in a soil which supplies high amounts of N and medium amounts of P and K.

Nitrogen The availability of N is the factor most likely to limit the growth of marijuana. For fast healthy growth, marijuana requires a soil rich in available N. Nitrogen is constantly being replaced in the soil solution by microbial breakdown of organic matter. Some microorganisms can use N directly from the atmosphere. They release N as waste in the form NO3, which is the primary form in which plants absorb N. A small amount of N is also dissolved in falling rainwater. When the soil is moist, it loses N through leaching and to plants. In its available form (NO3, NO2, NH4), N is very soluble and may be carried away with runoff or may drain into the subsoil.

Probably the most accurate method of measuring a soil's ability to produce N is by the percentage of organic matter in the soil (see Table 20). Organic matter releases N at a rate that is determined by the type of soil, the temperature, and the moisture. Generally, the more aerated and warmer the soil, the faster organic matter decomposes and releases N. Most professional testing services report the percentage of organic matter, and some sophisticated kits can also test for it.

In its available state, N is tested in two compounds, ammonium (NH4) and nitrate (NO3). Test results are converted into PPM (parts per million) of N and then added to arrive at the total amount of N available in the soil. The formulas to convert nitrate and ammonium to N are (NO3) * 0.226 = N, (NH4) * 0.78 = N. Each PPM indicates 10.7 pounds of N per acre available in the top 7.87 inches. If the soil level is deeper, there is probably more N available. If it is shallower, less is available. But a test for available N gives only a fair approximation of the soil's ability to feed the plant. An individual test may be untypical because of recent leaching or depletion during the growing season.

An intensively cultivated crop of hemp takes about 250 pounds of N per acre or six pounds per 1,000 square feet from the soil during the growing season. When the plants are spaced well apart, the crop does not require as much N.

Fields which have more than 200 lbs of available N per acre (or 4.5 lbs per 1,000 sq.ft.) at the start of the growing season require no additional fertilisation. Soils with less available N will probably yield a larger crop if they are given additional N. Actually, the amount of N that can profitably be used depends on the soil and its potential to produce N as well as on other factors: how fast N is lost, the soil depth, and moisture content.

One way to calculate the amount of N to add to the soil is to build your soil to an "ideal" level. For example, an Iowa silt loam may test about 1.6 pounds of N per 1,000 sq.ft. and an organic content of 3 percent. Together, the available and potential N total about 3.2 lbs per 1,000 sq.ft. To increase the available N to 4.5 per 1,000 sp.ft., you would need to add 1.3 lbs of N.

Phosphorus P is an important nutrient which is used directly by the soil bacteria as well as by the plant, so that an increase in the amount of P in the soil often results in an increase of N. Because of P's low solubility, it is rarely leached from the soil. It is usually found in the greatest concentration in the soil's top layers, where it accumulates as a result of decomposition of organic matter.

In slightly acid organic soil, up to one percent of the total P is available at any time. The total amounts of P in soils range from 1,000 to 10,000 lbs per acre. For example, a typical Kansas prairie soil has 3,000 lbs per acre. In soils with a lower pH, more of the P is tied up in insoluble compounds of iron or aluminium. In highly alkaline soils, the P forms insoluble compounds with calcium.

Insoluble P reacts with the dilute acids that are released during decomposition of organic matter. These compounds are available to the plants. Both the chemical processes in which P is released and the organic processes of decomposition occur faster in warm soils.

If P is available, young plants absorb it rapidly, and may take in 50 percent of their lifetime intake by the time they are only 25 percent of their adult size. Young plants grown outdoors in cold weather may grow slowly until the soil warms up and more P is available. Older plants grown out of season in cold weather sometimes exhibit purple leaves. This condition may result from a P deficiency, because of the unavailability of P at low temperatures.

Most soil-test kits test available P, but the nutrient value of P is usually expressed as phosphoric acid (P2O5), which is converted using the formulas P * 2.3 = (P2O5),(P2O5) divided by 2.3 = P. Any soil that has available P of 25 lbs per acre (0.58 lbs per 1,000 sq.ft.) or more is well-supplied with P. Stated in terms of phosphoric acid, this is 25 * 2.3 = 57.5 lbs per acre (1.33 lbs per 1,000 sq.ft.).

Most inexpensive soil kits test available P. Soil that test less than 1 PPM or 10.7 lbs per acre (0.25 lbs per 1,000 sq.ft.) of available P should be tested to make sure there are adequate reserves, or can be fertilised to assure maximum yield. Soil-test kits give only a fair indication of the P available. A low reading may indicate the plants are absorbing P as fast as it breaks down from its unavailable form, especially during early growth! The main factors affecting the rate at which P becomes available are the total amount of reserve P in the soil and the pH.

Most professional soil analyses include a report of reserve P. Generally soils with reserve P of 3,000 lbs per acre (70 lbs per 1,000 sq.ft.) do not need additional P. Intensively cultivated and cropped fields may have had their reserve supply depleted, and will lock up available P that is supplied as fertiliser until a balance is reached.

Potassium K is found in adequate quantities in most soils which have a pH within the range needed for growing marijuana. K is held in soils in three forms: unavailable, fixed, and readily available. Most K is held in the unavailable form as part of the minerals feldspar and mica. But a small percentage of the total K in any soil is held in fixed, slightly soluble forms. Some of these can be absorbed and used directly by the plant. The exchangeable K is equal to a fraction of the fixed K. Each soil maintains a balance or ratio of unavailable to fixed and to exchangeable forms. Organic soils have a higher percentage of K in the fixed or available form than mineral soils. As K is used by the plants, some of the unavailable K goes into the more available forms. Plants can use K in both the soluble and the fixed forms.

Most clays and soils that are well-limed have adequate reserves of K. Acidic soils generally have low K reserves. Mucks, silts, and peats have low reserves of K, and have little capacity to hold it chemically when it is applied. Sands have K reserves, but little capacity to convert it to a fixed or available form. Most western soils have adequate reserves or K. The exchangeable K in soils becomes fixed if the soil dries out; so the available K of a recently dried soil is usually low.

K is tested in its elementary state, but when described as a nutrient, it is given as potash (K2O). The formulas for converting are K * 1.2 + (K2O),(K2O) divided by 1.2 + K. Soils with 180 lbs or more of available potash per acre (4 lbs per 1,000 sp.ft.) have an adequate supply. The total reserve K should test no lower than 900 lbs per acre (21 lbs per 1,000 sq. ft.).

The Secondary Nutrients

Magnesium (Mg), calcium (Ca), and sulfur (S) are usually found in adequate quantities in soils suitable for growing marijuana. However, some New England soils do have Mg deficiencies. Soils which have a neutral or near-neutral pH almost always have adequate Ca and sulfur levels.

Magnesium deficiencies are corrected by adding 50 to 100 lbs of Mg per acre (2.25 lbs per 1,000 sq.ft.). The most inexpensive way to add Mg is to use a dolomitic limestone for adjusting soil pH. Dolomitic limestone is about 12 percent Mg (see Table 21); so 800 lbs of it are needed to supply 100 lbs of Mg. Dolomitic limestone releases Mg to the soil gradually. For faster action, epsom salts (magnesium sulfate, MgSO4) can be used. Five hundred lbs of epsom salts are required to supply soil with 100 lbs of Mg. Mg deficiencies can also be corrected by using foliar sprays. Dissolve one ounce of epsom salts in a gallon of water and spray all foliage.

{Picture The relationship between soil pH and relative plant nutrient availability. The wider the bar, the more the availability. This chart is for soil types recommended in this book..

{Nitrogen - pH of 6.3 to 8

Phosphorus - 6.5 to 7.5

Potassium - 6.5 to >9

Sulfur - 6 to >9

Calcium - 6.7 to 8.5

Magnesium - 6.5 to 8.5

Iron - <4 to 6

Manganese - 4.7 to 6.5

Boron - 5 to 7 or >9

Copper and Zinc - 5 to 7

Molybdenum - >7}}


Micronutrients are used by plants in minute quantities, and most soils contain enough of them to meet plant requirements. Home gardeners and guerilla farmers seldom encounter any micronutrient deficiencies. But heavily cropped lands sometimes develop a deficiency of one or more micronutrients because of crop depletion. Micronutrients are made available to the plants only if there is a delicate balance in the soil chemistry, and it is easy to create toxic conditions by adding them to soil when they are not needed. For that reason, soils should be treated with micronutrients only when symptoms occur or when the deficiency is known by analysis or past experience. Only small quantities of additives are required for treatment. Manures, composts, other organic fertilisers, lime, rock powders, and ash contain large quantities of trace elements. Active organic additives quickly release micronutrients in a form that is available to the plants.

Boron Boron deficiencies in marijuana occur in acid soils as a result of depletion by heaving cropping. The areas most affected by it are vegetable fields in the mid-Atlantic states, alfalfa and clover fields east of the Mississippi, and truck farms and orchards in the Northwest. Boron is found in phosphate fertilisers, gypsum, and lime, and is the main ingredient of boric acid and borax. When borax or boric acid are used, they are applied at the rate 10 to 20 lbs per acre. They are used as a foliar spray at the rate of 1 ounce per gallon of water.

Chlorine Chlorine deficiency does not normally occur. Some chemical fertilisers contain chlorine, and toxic conditions occur infrequently. Toxic chlorine conditions are eliminated by leaching.

Copper Copper deficiencies occur infrequently in truck farms in Florida, California, and the Great Lakes region. Wood shavings and tobacco contain large amounts of copper. A foliar spray composed of 1 ounce each of calcium hydroxide and copper sulfate (a fungicide) per gallon of water is used by commercial vegetable growers.

Iron Iron deficiencies occur in orchards west of the Mississippi and in Florida, and in alkaline soils in which iron is largely insoluble. Lowering soil pH often solves the problem. Chelated iron, which is water-soluble, is available at most nurseries and quickly supplies iron even when pH is extreme. Humus and seaweed are excellent sources of iron.

Manganese Manganese deficiencies occur in the Atlantic states, the Great Lakes area, Utah, and Arizona. Manganese is found in manure, seaweed, and some forest leaf mould (especially hickory and white oak). Manganese deficiencies can be corrected by using a foliar spray of manganese sulfate at the rate of 0.5 to 1.0 oz. per gal. Soil is sometimes treated with manganese sulfate at the rate of 20 to 100 lbs per acre. In neutral or alkaline soils, most of the manganese sulfate becomes fixed and unavailable to the plants by the end of the growing season.

Molybdenum Molybdenum deficiencies occur primarily along the Atlantic and Gulf coasts and in the Great Lakes region. Plants need extremely small amounts of molybdenum, less than 1 PPM in leaf and stem tissue. Molybdenum deficiencies occur when the soil is too acidic. By raising the pH level, one can make molybdenum available.

Zinc Zinc deficiencies occur in soils throughout the U.S., primarily because of heavy cropping. It is most likely to occur in acid-leached sandy soils, and in neutral and alkaline soils where it is insoluble. In soils with high amounts of available P, zinc is also unavailable. Many deciduous tree leaves and twigs, composts, slag, and rock phosphate contain large amounts of zinc. Zinc sulfate is used as foliar spray at the rate of 3 oz. of zinc sulfate per gallon of water, or as a soil treatment at the rate of 100 lbs per acre. Some orchard growers drive galvanised nails into the trees to provide zinc.


Most soils can benefit from a realistic soil-conditioning program. Most organic programs build soil, and minimise leaching and runoff. Programs using chemical fertilisers emphasise immediate increase in yield and a minimum of labor. The approach that you use should be tailored to the soil's needs and to your situation and goals. For example, a home gardener interested in building soil quality can easily add manure or compost to his garden. But a guerilla farmer may use concentrated chemical fertilisers, which are easy to transport to a remote area. A farmer cannot use the labor-intensive techniques which a small planter might use as a hobby. Many gardeners use both organic and inorganic fertilisers.

Organic Fertilisers

Organic fertilisers are usually less concentrated than chemical mixes. Their bulk consists of fibrous materials which condition the soil by aiding drainage and increasing the organic content and water-holding capacity. As they are decomposed by microbial action, the nutrients they contain are released in soluble form. Since this is a gradual process, there is little chance of creating toxic conditions.

Manures and composts are basic, all-purpose conditioners. They contain adequate amounts of most of the nutrients that marijuana absorbs from the soil and can be used generously. Uncomposted manures are "active" and should be used only in the fall. Over the winter they compost in the ground. Composts and composted manures can be added in the spring. Table 22 lists some common organic fertilisers which are usually available. Some of them, such as bone meal and granite dust, break down slowly and are available only after a period of time. Others are low or lacking in one or more of the major nutrients. Organic fertilisers can be combined to provide a complete balance.

Chemical Fertilisers

Most chemical fertilisers act quickly because all the nutrients are in soluble form. They are usually more concentrated than organic fertilisers, and can toxify the soil and kill the plants when they are overused. Fertilisers come in various concentrations and ratios of nutrients. All packaged fertilisers list the percentages of N-P-K (actually n-(P2O5)-(K2O)). Also listed is the potential acidity or alkalinity, that is, the number of pounds of lime or sulfur required to counteract pH changes caused by the fertilisers. Chemical fertilisers are often incompatible with each other; so home gardeners who use them should buy them pre-mixed or as a complete component fertiliser set.

Solubility is a major problem with commercial fertilisers. In irrigated areas as well as areas with rainfall during the growing season, they are likely to be leached away; so they must often be applied several times during the growing season. A typical program might be to fertilise at planting and every six weeks thereafter until the beginning of flowering. When spreading fertilisers during the growing season, do not let them come into direct contact with the roots. An easy way to fertilise during the growing season is to make a small trough between rows with the corner of a hoe. Fertiliser is placed in the depression. Some new chemical formulas release nutrients during the length of the growing season, and therefore need only one application.

Amounts to Use

The amounts of nutrient needed per acre and per 1,000 sq.ft. are shown in Table 23. Soils rich in one nutrient may be average or deficient in another. To calculate the required amount of a specific fertiliser, divide the amount of nutrient required as listed in the chart by the percentage of nutrient in the fertiliser. For instance, to add 5 lbs of N to an area by using bloodmeal, divide 5.00 by 0.15. The total comes to a little more than 33 lbs. Dried cow manure contains about 1.5 percent N. About 333 pounds of it are needed to supply 5 lbs of N. Urea, a chemical fertiliser, contains 46 percent N. Only 11 pounds are required to supply 5 lbs of N.

Planning a Garden Fertiliser Program

Now let's plan some garden fertilisation programs, to help some cultivators in three areas which have different soils and climates: New England, Kansas, and Florida. We'll see how growers with different goals adjust their garden soil.

New England Most New England soils, and many soils in humid temperate areas, have a thick layer of humus which supplies N. New England soils also contain moderate amounts of P, but they are low in K.

Our first gardener has a typical New England soil in his backyard. From tests and observation he thinks his soil contains moderate amounts of N and P, but is low in K. A test indicated a pH of 5.8. He plans to start preparing his ten-foot-square plot (100 sq.ft.) in the fall, before frost. By planting time, he expects his backyard garden to have a pH of 6.7 and a balanced, fertile soil.

From Figure 59 he finds that the soil requires about 8.1 lbs of lime. He has decided to adjust the pH by using dolomitic limestone (with a calcium carbonate equivalent of 0.45) because farmers in the area sometimes complain of Mg deficiencies. Dividing 8.1 by 0.45, he finds that the soil requires 18 lbs of limestone. (Lime requirements divided by calcium carbonate equivalent equals the amount of limestone needed.)

He guesstimates that the N content of his soil rates between fair and medium, and figures the soil can use almost 0.2 lbs of N. He has decided to spread fresh manure from a nearby stable mixed with lime. In the spring he will turn this into the soil; at the same time, he will add manure composted with hay and table scraps. The fresh horse manure contains about 0.44 percent N. To find out how much manure he needs, he divides 0.2 (the amount of N required) by 0.0044. The total comes to about 45.5 lbs. (Nutrient required divided by percentage in fertiliser equals amount of fertiliser needed.) The manure also contains 0.17 percent phosphoric acid (P2O5) and 0.35 percent potash (K2O), referred to hereafter in this chapter as P and K, respectively. Multiplying 0.17 percent (0.0017) and 0.35 percent (0.0035) by 66 lbs, he finds that he has added 0.11 lbs of P and 0.23 lbs of K. (Lbs of fertiliser times percentage of nutrient in fertiliser equals amount of nutrient in fertiliser.)


Chemical fertilisers usually supply P in the form of superphosphate or triple superphosphate. These chemicals are manufactured by mixing rock phosphate with acids. Potassium is supplied by means or muriate of potassium (K and chlorine) or sulfate or potash, which are mined in the Southwest and purified. All these chemicals are soluble and are available to the plant. But a portion of them gradually reacts with the soil and becomes fixed or unavailable. As this portion becomes unavailable, it increases the total reserve in the soil, which reaches a new balance of available to unavailable nutrients than before fertilisation.

Bone meals and rock phosphate, the most commonly used organic sources of P, and granite dust, a source of K, are not readily available, but increase the total reserve of nutrients and gradually increase the total amount of available nutrients. However, there is some time lag before these nutrients are available to the plant. They are usually applied in large amounts, at about three times the weight calculated for fertilisers of that concentration. But one treatment lasts four years or more, because the fertilisers remain fixed in the ground until they are used. {Table 24}

From Table 23 he finds that the soil requires about five ounces of P. How many ounces of P is 0.11 lbs? He multiplies 0.11 by 16, the number of ounces in a pound, and finds that the total is about 1.75 ounces. The soil requires another 3.25 ounces. Bone meal is about 20 percent P. To supply three ounces of P, about a pound of bone meal is required. But bone meal breaks down slowly, and is therefore applied at three times the rate used for other fertilisers; so our cultivator uses 3 lbs.

Since the K content of this New England soil is poor, about 0.3 lbs of K is required. The manure has already supplied 0.2 lbs; so the soil requires another 0.1 lb. Our cultivator decides to use wood ashes from his fireplace. Wood ashes are about 7.0 percent K. He divides 0.1 by 7 percent (0.07) and finds that the soil can use at least 1.4 lbs of ashes. He adds this in the spring just before planting, because the ashes are highly soluble. Over the winter, such highly soluble nutrients would leach away or become unavailable.

Our grower knows that some of the N in the fresh manure that was added in the fall will leach away during the winter. But the manure compost that he adds in the spring will more than make up for any losses.

A New England farmer not for from the cultivator has been rotating his field from corn and marijuana to alfalfa and pasture for the past ten years. Each fall he adds 7 tons of manure per acre. Except for occasional additions of lime, no other fertilisation is necessary.

A rural New England grower has decided to plant in a remote mixed-forest area. The first 10 inches of soil is a rich compost of humus. It is full of life: insects, worms, and other creatures. The grower has decided to increase the fertility of the soil by using chemical mixes and dolomitic lime. He is cultivating in three clearings with a total area of about 1,000 sq.ft. He guesstimates that the soil is medium in N and P, but poor in K. It is also acid. He applied enough lime to correct the soil's natural acidity and the pH of the fertiliser.

Using Table 23, he decides that he should purchase a mix with a ratio of 50 parts of N, 10 parts of P (reading from the medium line), and 120 parts of K (from the poor line), that is, a ratio of 5-1-12. A local nursery sells commercial fertiliser with nutrient percentages of 10-5-25, close enough to the desired ratio. By taking the total amount of N required for a medium soil as listed in Table 23 (19 ounces), and dividing it by the N in the fertiliser (10 percent or 0.10), the rural grower finds the total amount of fertiliser required (190 ounces, or a little less than 12 lbs). The other nutrients are automatically added in the same ratio.

Kansas A cultivator in Kansas decides to plant along a hidden stream bank. The banks are covered with lush vegetation as a result of runoff that contains soluble fertilisers used on nearby farms. The cultivator feels that additional fertilisers are not necessary, since the vegetation is so lush.

Another grower in Kansas found that her soil was very low in N and P, but high in K, typical of dry midwestern and western soils that support scrub vegetation. It had a nearly ideal pH. She started to prepare her 200 sq.ft. garden in the spring after the rain season ended. Using Table 23, she found that it required 3.5 lbs of N, 6 ounces of P, and no K. Activated sludge (5-3-0) was available at the local garden centre. To find out how much sludge her garden required, divide 3.5 by 5 percent (or 0.05). The total comes to 70 lbs.

Florida A grower planting 500 sq.ft. on a deserted ranch in central Florida started with a very sandy soil whose pH was 4.9 because of sulphurous water in the ground. From Figure 59, she found that the soil required about 35 lbs of lime. To adjust the pH, she used 14.0 lbs of a limestone with a calcium carbonate equivalent of 2.5.

The soil had virtually no organic matter, and she was not sure she could use the same location next year; so she decided to apply soluble mixes throughout the growing season. From Table 23, she found that "poor" required 28 ounces of N, 4 ounces of P, and 24 ounces of K. A chemical fertiliser with nutrient percentages of 15-5-10 was on sale at a local discount store. To find out how much fertiliser is needed to supply 28 ounces of N, divide 28 by 15 percent (or 0.15); the result is about 186 ounces of N, or about 11.5 pounds. Since the other nutrients are supplied at the same proportions or at higher proportions than are required, no supplements are needed at planting time. But additional feedings will be required periodically during the growing season.

Techniques for Preparing Soils

Each garden situation is unique, and many factors help determine which garden techniques you should use. These include the soil's condition, the size and location of the garden, commitment, and personal preferences. Each technique affects the microecology in its own way. Home gardeners may use techniques that are impractical for a farmer or guerilla planter. But all growers have the same goal when they prepare soil for planting: to create a soil environment conducive to growing a healthy, vigorous plant.


Fertilising Cannabis Depends on the Crop

Historically, Cannabis is known to require high fertility. In a fertile soil, Cannabis can outgrow practically any annual plant. Cannabis also is a known depleter of soils. This is true particularly with marijuana, since seeds, flowers, and leaves comprise the harvest. Hence it's necessary to fertilise the plants each year.

Hemp, on the other hand, comes from the Cannabis stem, and the fibre consists primarily of cellulose (C6H10O5)n. When hemp is grown, all plant parts except the fibre are returned to the soil; so the nutrients are also returned. Moderate fertilisation, if any, is all that's required for hemp farmers.

If you are already growing a vegetable garden, the chances are that your soil is in pretty good shape for growing marijuana. However, vegetable gardens may be a little acidic, particularly east of the 100th meridian. The soil should be prepared in much the same way that it is prepared for corn cultivation, with the addition of lime to raise the pH to near neutral.


Gardens which may not have been planted recently (in the last three or four years) require more work. It is best to begin preparing the soil in the fall, before the first frost. This can be done using a spade or shovel. The ground is lifted from a depth os six or eight inches and turned over so that the top level, with its grass and weeds, becomes the bottom layer. Large clumps are broken up with a blade or hoe. Larger areas can be turned with a power hoer or rototiller. Conditioners, such as fresh leaves, composts, mulching materials, pH adjusters, and slow-release fertilisers are added and worked into the soil, so that they begin to decompose during the winter. It is especially important to add these materials if the soil is packed, mucky, or clay-like. Soluble fertilisers should not be added in the fall, since they leach to the subsoil with heavy rains.

In the spring, as soon as the ground is workable, turn it once again. If the soil still feels packed, add more conditioners. If you are using manure or other organic materials, make sure that they are well decomposed and small clean and earthy. Fresh materials tie up the N in the soil while they cure, making this nutrient unavailable to the plants. Commercial fertilisers and readily soluble organics, such as blood meal and wood ash, are added at this time.

The ground can also be seeded with clover or other legumes. Legumes (alfalfa, clover, vetch, etc.) are plants which form little nodules along their roots. The nodules contain bacteria which live in a symbiotic relationship with the plant. As part of their life processes, these bacteria absorb gaseous nitrogen from the air and convert it into a chemical form the plant can use. During its life cycle, clover uses up most of the N, although some leaks into the surrounding soil. But when the plant, or any of its leaves, die, the contents become part of the soil. The process of growing a cover crop and turning it into the soil is sometimes called green manuring.

After the last threat of frost, at about the same time that corn is planted, the soil should be worked into rows or mounds, or be hoed. At this time, the seeds should be planted. If any concentrated fertiliser is added to the soil, it should be worked into the soil and should not come into direct contact with the seeds.

The actual amount of tilling that a given soil requires depends on soil condition. Sandy soils and light loams may need no turning, since they are already loose enough to permit the roots to penetrate. Turning may break up the soil structure, damaging its ecology. These soils are easily fertilised, by using soluble mixes or by the layering technique described below. Soils which are moderately sandy can be adjusted by "breaking" and levered or pushed, but the soil is not raised. This is done about every six inches, and can be accomplished quickly. Farmers can loosen sandy soil by disking at five or six inches.

Some gardeners mulch the soil with a layer of leaves or other materials to protect it from winter winds and weather. This helps keep the soil warm so that it can be worked earlier in the spring. In states that border west of the 100th meridian, this helps prevent soil loss due to erosion from dry winds. Soil often drains well in these areas, and the ecology of the soil is better served when it is left unturned. At season's end, marijuana's stem base and root system are left in the ground to help hold topsoil. The next year's crop is planted a cover crop, such as clover, or alfalfa, which holds the soil and also enriches the nitrogen supply.


Layering is another method of cultivation. The theory behind this program is that in nature the soil is rarely turned, but builds up, as layer after layer of compostable material falls to the ground. This material, which contains many nutrients, gradually breaks down, creating a rich humus layer over a period of years.

The layering method speeds up the natural process. Since gardens are more intensely cultivated than wild fields, new material is required to replenish the soil nutrients. Gardeners like Ruth Stout "sheet compost," that is, they lay down layers of uncomposted material and let it decompose at the same time that it serves as a mulch. But most gardeners prefer to use material which is already composted. The compost shrinks and builds the topsoil layer about an inch for every six inches of compost. After several years, the soil level will be raised considerably, and the top layers will be an extremely rich, porous medium which never needs turning. In order to prevent a spillover of the soil, gardeners usually construct simple beds (using boards) to contain the garden areas.

Layering is most successfully used on porous soils, especially sands, which contain little organic matter. It can also be used with clay soils. However, experienced growers say that clays should be turned several times before the technique is used, or the first couple of harvests will be small.

Planting a cover crop such as clover will give the soil structure. As more compost is added, the clover is covered and the new seed planted. The clover, with its N-fixing properties, remains a permanent cover crop. When marijuana seeds are to be planted, a planting row is easily tilled with a hoe. The clover protects the soil from sun-baking and its resulting water loss, and makes it harder for weed seeds to get started.

Tilling and layering are basic methods which are used with many variations. In some ways, there almost seem to be as many gardening techniques as there are gardeners. For instance, one gardener bought three cubic yards of topsoil and a cubic yard of composted steer manure. He mixed the material and filled raised beds with it to a depth of 18 inches, and had an instant high-power garden. Another grower made compost piles in his raised troughs during the winter. By planting time, the compost was complete and filled with earthworms. The beds became warmer earlier, and he could plant sooner.

A midwestern gardener used marijuana as a companion crop in much the same way Indians used corn. In between the marijuana, she planted beans and squash. She didn't get many stringbeans and only a few squash. But she believes that the beans gave the plants extra N, especially during the first six weeks, and the broad squash leaves protected the soil from the hot August sun.

A gardener in Georgia had such a sticky clay soil that a shovel once got stuck in it. He dug holes two feet deep and two feet wide with a power auger and filled them with a fertile mix of two parts sand, one part clay, three parts topsoil, and one part chicken manure. He claimed that his plants grew six feet in 10 weeks. Filling holes with a rich soil mixture is popular with guerilla farmers, who often must plant in poor native soils.


Mulching is a labor-saving technique that many gardeners and farmers use for a multitude of reasons. A mulch placed on the ground before fall frosts helps the soil retain heat and protects it from winds and freezing temperatures. In the spring the mulched soil becomes warmer earlier in the season, and can be planted several weeks sooner than usual. A mulch cover keeps the seedlings' roots warm and eliminates a lot of weeding, since most weed seedlings cannot pierce the cover.

During the summer, mulches keep the ground cooler and more moist by absorbing and reflecting light and reducing surface evaporation. These are important points for farmers in dry areas. The water savings can be 50 percent or more.

Any plant or animal material will do for mulch. Gardeners use hay or straw, leaves, composts, manures, sawdust, bark, or plant clippings in two- to six-inch layers. A barber in Palo Alto uses hair. Baled hay is inexpensive and easy to use as a mulch. Round hay bales unroll in a long sheet that is easy to spread over the ground, and square bales can be pulled apart into tile-like squares.

Mulches create an ideal environment for earthworms and microorganisms which condition and enrich the soil. These organisms require a relatively cool, moist, dark environment. The mulch develops a dry outer crust which reflects light, keeping the underlayers cool and moist. Materials such as leaves, bark, and sawdust decay slowly because they do not contain enough nitrogen to maintain dense populations of decomposing microorganisms. Manures and composts contain more nitrogen and decay more quickly.

With few exceptions, mulches can be applied practically any time of the year, but the best time is probably in the fall, after the crop is harvested and before the ground has frozen. Leaves, plant clippings, and straw are applied in a thick layer from six to ten inches deep. Hay is layered two to six inches deep. Denser substances, such as manures and composts, should be mixed with straw and leaves to aid decomposition. This mixture is spread in an even layer, about two to four inches deep, over the entire surface of the garden. If winds pose a problem by blowing the mulch away, you can cover it with newspapers or sheets of plastic held down with rocks. If your area is dry, give the mulch a good soaking once before frosts.

By the spring, much of the material will seem to have disappeared. But underneath the top layer, you will find a soft-textured, earthy-smelling humus, teeming with worms, insects and other small animals. This is a sign of a healthy ecosystem and a fertile soil.

Some people apply mulch in the spring, placing it between rows as they sow the seeds. The mulch keeps weeds from competing with the seedlings, absorbs the sun's warmth, and releases nutrients to the soil.

In cold areas, such as Montana, New England, and Alaska, growers place black plastic sheets over the soil. These absorb the sun's heat, allowing the soil to be planted sooner. The seedlings develop quickly in the warmer soil. The plastic is removed once the seedlings are well-established.

Newspapers and white plastic can be used to decrease water loss during the summer. They also reflect light back to the plants.

One innovative grower from western Colorado placed a sheet of white plastic over her garden and cut out holes wherever she plant the seeds. Though it is quite dry where she lives, she didn't need to water the plants until late July. And she had no problems with any weeds.


Containers are another option open to grower. Plants can be grown full-size in containers which are at least five gallons (larger would be better). Fill them with high-grade topsoil, or a plating mixture as described in section 6. Planters are a convenient compromise where the soil is particularly poor or for the home gardener who does not wish to get into large-scale gardening. But remember, eight good-sized plants can yield over four pounds of grass.

Plants in pots need to be watered frequently, but require much less total water than a garden. The gardener can also move the plants. Some gardeners use this technique to maximise the amount of sun the plants get during the day, or as the sun's position changes with the season. And growers can easily induce early flowering by moving the plants to a darkened area. {Figure 61. Containers are convenient for outdoor gardens.}

Almost any large container that can withstand the weight of moist soil and which has holes for drainage is suitable. Containers which held toxic chemicals, herbicides, insecticides, or other possibly harmful substances should be avoided.

We have seen all kinds of ingeniously made containers. Some growers use old bathtubs, and others use wooden packing crates or bushel baskets. A simple wood container 18 inches wide, eight feet long, and 18 inches deep was made by a New Jersey grower, who grew six plants in it. Trash cans, plastic containers, barrels, and even rubber tyres have been used. One grower grew plants in one-cubic-foot bags of soil by cutting a five-inch-diameter hole in the top and poling holes for drainage. To assure drainage, growers sometimes fill the bottom of each container with a six-inch layer of stones or gravel; is you are planning to move such container, lightweight perlite would be more suitable.

Guerilla Farming

Guerilla growers often use the same techniques as home gardeners. But the soil that they start with is sometimes marginal, and the gardens are in remote, hard-to-get-to areas; so they modify the techniques to fit their needs. When it is impractical to carry bulky organic fertilisers to the growing site, guerilla farmers use highly concentrated commercial mixes. Compost and soil adjusters are gathered from the surrounding area, and the simplest, most light-weight tools are used. Some growers use horses or mules to carry equipment and material, and then use the animal to plough. The animals are quiet and naturally, require no external power source. Experienced growers say that the animals can work as fast as or faster than a rototiller.

It is hard to generalise about details of guerilla farming, since much depends on the specific circumstances, which can vary greatly. For instance, a grower who plants along the fertile bank of a midwestern stream may not need to do more than pull out weeds and till the actual planting area. But a grower planting on a mountain slope may have to "build a soil," since soil and nutrients are washed from the slopes and down to the valleys by rainfall. For this reason, we will cover several situations separately: forest; washed-out steep areas; swamps and marshes; stream banks; grasslands and fields; and arid soils.

Forest Clearings

Clearings in forests have always been popular places to plant because they offer security from detection. They vary greatly in drainage qualities, fertility, and pH. The drainage qualities of forest soils depend on the depth of the humus layer and the structure of the underlying subsoil. But most of the forest remaining in the U.S. is sloped, and water that is not absorbed by the soil runs off.

Soils are created in forests from the leaves, branches, animal droppings, etc., which accumulate on the forest floor. The first trees to grow are long-leaf pines, such as jack pines, which can grow in relatively infertile soils. Their roots penetrate deep into the subsoil to obtain some nutrients. Short-leaf pines, conifers, and firs appear as the humus accumulates, since they require a more fertile soil than long-leaf pines.

Pine-forest soils vary in fertility from poor to fair, and are usually quite acidic. In the Northeast their pH may be as low as 3.5, but generally the pH ranges from 5.0 to 6.0. In order to support a high-energy, lime loving crop like marijuana, they require fertilisation and liming. Long-leaf pines sometimes grow in compacted clay soils, which also requires tilling.

As the soil evolves, deciduous trees (tree that drop their leaves each winter), such as oak and maple, may begin to grow. Deciduous forests, sometimes called broad-leaf or hardwood forests, have the best soils. These forest floors are covered with bushes, grasses, mosses, and other small plants. They have an adequate rainfall and a humus-rich soil, which is porous, holds water well, and can support a healthy marijuana crop, although additions of nitrogen fertilisers would probably spur growth. Hardwood forest soils have a pH range from 6.0 to 7.5. The soil in timbered forest land has a much smaller humus content, especially if it has been clearcut.

Mountain Soils and Washed-Out Steep Areas

Mountain slops characteristically have little soil matter; their surface is composed largely of rocks, gravel, and sand. For longterm use they could be terraced so the newly formed soil in not washed away, but most growers are interested in more immediate results. These "soils" do not provide much of an anchor for marijuana's taproot and do not permit a network of lateral roots to form. Many of these soils also suffer from a low water table, since they drain rapidly. But there may be some sand and a bit of organic matter built up along gullies or in depressions or other natural traps. Such soil has usually had most of its nutrients leached out, but may contain some phosphates and potassium and considerable amounts of trace elements. The easiest way to adjust these soils is to use a well-balanced, slow-release, concentrated fertiliser. Bloodmeal, with its high N, works well with these soils.

One grower in the badlands of North Dakota used a timed-release 32-9-26 fertiliser in his "rock garden." He spread it just below the surface at the beginning of the growing season. Every time that it rained, his plants received nutrient-rich water. Toward the middle of the season, he noticed the lower leaves begin to pale, so he fertilised them periodically with urea. Heavy rains leach soluble fertilisers away, and in rainy areas they need to be applied three to four times during growth.

Containers can also be used in this environment. Growers use plastic bags or folded milk cartons instead of backpacking with a column of containers. When they get to the site, they fill the bags with a mixture of sand, as much as they can find, and gravel. The greater the ratio of sand to gravel, the longer the container will hold water.

One grower doublelayers heavy-duty polyethylene bags, and lines them with heavy-duty paper cement sacks or burlap bags. He fills the bag with gravel, then pours in sand and shakes it. He says that the mix is just about right when it looks like a can filled with gravel with sand in the spaces. He carries on a watering and feeding program much as he would for any hydroponic system.

Swamps, Marshes, or Bogs

These soils are very high in fibrous organic material, but are low in calcium and in available N, P, K, and Mg, which are leached from the soil or are insoluble because of the low soil pH. Since these soils are constantly wet, Cannabis roots cannot come in contact with air; as a result, the plant's growth is stunted, and the lower stem becomes susceptible to stem rot. These soils need to be adjusted to support a healthy crop of marijuana; they must be drained, fertilised, and limed. On a small scale, the easiest way to modify them is by constructing raised mounds, hills, or rows, at least one foot wide at the top and two feet high. The raised areas drain well, leaving relatively dry soil. Wood chips, chopped brush, sawdust, or perlite may be added to keep the mound light and the soil loose and aerated.

Wet soils are usually highly acid and should be limed. Once the lime interacts with the soil, nutrients which were locked up become available to the plants. Since these soils are rich in organic matter and have a high rate of microbial action after they are loosened and limes, they may need little fertilisation.

Grasslands and Fields

These soils are usually fairly fertile and can support a worthwhile crop with little effort. They are usually well-drained, although they may be a little too dry or too wet. (If they have unusually large numbers of earthworms, they are probably a little too wet.) Their pH is usually between 5.5 and 6.5, although it may range up to 7.0. These soils are usually loams, which need only tilling in a two-foot radius, three or four inches deep, around each plant. All weeds and grass should be pulled from the area. Some growers mulch the cultivated area with newspapers, leaves, or dead grass. A grower in the Midwest adds crushed eggshells and a commercial timed-release fertiliser when he plants. He feels that this "extra boost" makes the difference between an adequate crop and a bountiful crop. Other growers periodically fertilise with soluble mixes. Some of these soils have to be irrigates during the long summer droughts. If they aren't, the plants won't die, but they will not grow to full size.

Stream Banks and Canal Ditches

These are some of the most convenient areas for growers to plant, since they provide an ample supply of water, which may contain fertiliser runoff. Stream banks are an area that marijuana naturally colonises, and the planter usually needs only to cultivate the area to be sown, and cut surrounding bush so that the young plants can compete with established plants. It the surrounding vegetation looks pale and stunted rather than lush green and vigorous, the soil should be fertilised. These soils are sometimes low in calcium, which dissolves readily in water. Lime should be added to correct for acidity.

Sometimes the ground is a little too wet early in the growing season, although it dries out later on. Planting on hills or mounds is often used to solve this problem.

Arid Areas

Soils which have a low water table and dry out by June or July need to be irrigated to grow marijuana successfully. When irrigation is not feasible, growers plant along drainage ditches, streams, and canals, or look for green spots which indicate springs or underground reservoirs. Other growers use containers to minimise water loss. One grower in Arizona dug holes two feet wide and three feet deep, and lined the sides with thin polyethylene. He said that when he watered during the summer drought, he did not lose much water to the surrounding soil.

Arid soils usually have little organic matter, and drain quickly with extensive runoff. Some of them have a subsurface layer of clay, and therefore hold water on the surface until it evaporates. In any case their texture can be improved greatly by working in organic matter. The soil should be loosened at least two feet down. This loosening allows the taproot to develop deeply so that it can reach underground water during the drought.

Arid soils more often drain well, are alkaline, and contain P, K, and trace elements, but are low in N. Fish meal, cottonseed meal, blood meal, or manure may be the only additive the soil needs.