Marijuana Horticulture: The Indoor/Outdoor Medical Grower's Bible

peat pots before it gets entangled with roots. To transplant, set the peat pot or root cube in a pre-drilled hole in a rockwool block or into larger pot. Clones and seedlings suffer little or no transplant shock when transplanted properly.

Seedling trays are easy to use.

Small rockwool plugs are fast to plant and easy to maintain.

Rockwool plugs grow strong root systems in about two weeks.

Coarse perlite is lightweight.
    Check moisture levels in peat pots and root cubes daily. Keep them evenly moist but not drenched. Root cubes and peat pots do not contain any nutrients. Seedlings do not require nutrients for the first week or two. Feed seedlings after the first week and clones as soon as they are rooted.
    Coarse sharp sand, fine vermiculite, and perlite work well to root cuttings. Sand and perlite are fast draining, which helps prevent damping-off. Vermiculite holds water longer and makes cloning easier. A good mix is one third of each: sand, fine perlite, and fine vermiculite. Premixed seed starter mixes sold under such brand names as Sunshine Mix and Terra-Lite are the easiest and most economical mediums in which to root clones and start seedlings. Soilless mix also allows for complete control of critical nutrient and root stimulating hormone additives, which are essential to asexual propagation.
Soil Amendments
    Soil amendments increase the soil’s air-, water-, and nutrient-retaining abilities. Soil amendments fall into two categories: mineral and organic.
    Mineral amendments are near neutral on the pH scale and contain few, if any, available nutrients. Mineral amendments decompose through weathering and erosion. Add mineral amendments to augment air and increase drainage. They have the advantage of creating no bacterial activity to alter nutrient content and pH of the growing medium. Dry mineral amendments are also very lightweight and much easier to move in and out of awkward spaces.
    Perlite is sand or volcanic glass expanded by heat. It holds water and nutrients on its many irregular surfaces, and it works especially well for aerating the soil. This is a good medium to increase drainage during vegetative and flowering growth, and it does not promote fertilizer- salt build-up. Versatile perlite is available in three main grades: fine, medium and coarse. Most growers prefer the coarse grade as a soil amendment. Perlite should make up one third or less of any mix to keep it from floating and stratifying the mix.
    Pumice, volcanic rock, is very light and holds water, nutrients, and air, in its many catacomb-like holes. It is a good amendment for aerating the soil and retaining moisture evenly. But like perlite, pumice floats and should constitute less than a third of any mix to avoid problems.
    Hydroclay is used more and more as a soil amendment in containers. The large expanded clay pellets expedite drainage and hold air within the growing medium. See Chapter Twelve “Hydroponic Gardening” for more information.
    Vermiculite is mica processed and expanded by heat. It holds water, nutrients, and air within its fiber and gives body to fast-draining soils. Fine vermiculite holds too much water for cuttings, but does well when mixed with a fast-draining medium. This amendment holds more water than perlite or pumice. Used in hydroponic wick systems, vermiculite holds and wicks much moisture. Vermiculite comes in three grades: fine, medium, and coarse. Use fine vermiculite as an ingredient in cloning mixes. If fine is not available, crush coarse or medium vermiculite between your hands, rubbing palms back and forth. Coarse is the best choice as a soil amendment.
    Organic soil amendments contain carbon and break down through bacterial activity, slowly yielding humus as an end product. Humus is a soft, spongy material that binds minute soil particles together, improving the soil texture. New, actively composting organic soil amendments require nitrogen to carry on bacterial decomposition. If they do not contain at least 1.5 percent nitrogen, the organic amendment will get it from the soil, robbing roots of valuable nitrogen. When using organic amendments, make sure they are thoroughly composted (at least one year) and releasing nitrogen rather than stealing it from the soil. A dark, rich color is a good sign of fertility.

Pumice is lighweight

Vermiculite is lightweight and absorbent.

Some growers use organic potting soil as a soil amendment.

This bag of soil amendments contains well-rotted mulch and chicken