Each garden situation is unique: the soil’s condition, the garden’s size, its location, your commitment, and your personal preferences all play their part in determining which garden techniques you should use. Each technique affects the micro-ecology in its own way, and is useful for some set of conditions. Home gardeners can use techniques that are impractical for a farmer or a guerrilla planter. But all growers have the same goal when they prepare soil for planting: to create a soil environment conducive to the growth of a healthy, vigorous plant.
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 as it is for corn, with the addition of lime to bring the pH close to neutral.
TILLING
Gardens that have not been planted recently (that is, within the past 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 of 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 power hoe or roto-tiller. Conditioners such as fresh leaves, composts, mulching materials, pH adjusters, and slow-release fertilizers are added and worked into the soil so that they can begin to decompose over the winter. It is especially important to add these materials if the soil is packed, mucky, or clayey. Soluble fertilizers 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, it should be turned once again. If it still feels packed, add more conditioners. If you are using manure or other organic materials, make sure that they smell clean and earthy and are well-decomposed. (Fresh materials tie up the nitrogen in the soil while they cure, making it unavailable to the plants.) Commercial fertilizers 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 (clover, alfalfa, 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 process, these bacteria absorb gaseous nitrogen from the air and convert it to chemical forms that can be used by the plant. During its life, the legume uses up most of the nitrogen, although some leaks into the surrounding soil. However, when the plant dies (or when any of its leaves die), its contents become part of the soil. The process of growing a cover crop and turning it into the soil is 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 hoed, and the seeds planted. If any concentrated fertilizer is added to the soil, it should be worked into the soil first, rather than coming into direct contact with the seeds.
The actual amount of tilling that a soil requires depends on its condition. Sandy soils and light loams may need no turning, since they are already loose enough to permit the roots to penetrate. Since turning breaks up the soil structure, damaging its ecology, it should be done only when necessary. These soils are easily fertilized using soluble mixes or by the layering technique described below. Soils which are moderately sandy can be adjusted by “breaking” them with a pitchfork: the tines are pushed into the ground and may be levered, but the soil is not turned. 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 it can be worked earlier in the spring. In states west of the 100th meridian, this is helpful for preventing soil loss due to erosion from dry winds. Soil often drains well in these areas and the soils’ ecology is better served when they are not turned. At season’s end, the marijuana’s stem base and root system are left in the ground to help hold the topsoil. The next year’s crop is planted between the old plant stems. Some gardeners prefer to plant a cover crop such as clover or alfalfa, which holds the soil while enriching the nitrogen supply.
LAYERING
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 fails 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. Some gardeners sheet-compost: that is, they lay down layers of uncomposted material and let it decompose while serving as a mulch at the same time. Most gardeners, however, prefer to mulch with material that 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 constitute an extremely rich, porous medium which never needs turning. In order to prevent a spillover of the soil, gardeners usually construct beds which contain the garden areas. These are simply constructed with boards.
Layering is most successfully used on porous soils, especially sands, which contain little organic matter. It can also be used with clay soils, but experienced growers say that clays should be turned several times before the technique is used, or the first few harvests will be small.
Planting a cover crop such as clover will give the soil structure. As more compost is added, the clover will be covered and the new seed planted. The clover, with its nitrogen-fixing properties, remains as a permanent cover crop. When marijuana seeds are to be planted, a planting row can easily be tilled with a hoe. The clover protects the soil from sun-baking and resultant water loss, and makes it harder for weed seeds to get started.
Tilling and layering are basic methods, and are used in many variations. There are almost 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 1½ feet, creating 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 warm earlier, enabling him to plant sooner.
A Midwestern gardener uses marijuana as a companion crop in much the same way as Indians used corn: between the rows of marijuana, she planted string beans and squash. She didn’t get many beans, and only a few squashes, but she points out that the beans gave the plants extra nitrogen, especially during the first six weeks, and that 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 had once become stuck in it. He used a power auger to dig holes two feet deep and two feet wide, 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 2½ months.