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

compost piles high, and keep turning them. Good compost pile recipes include the addition of organic trace elements, enzymes, and the primary nutrients. The organic matter used should be ground up and in the form of shredded leaves and grass. Do not use large woody branches that could take years to decompose.
    Before using compost indoors, pour it through 0.25-inch mesh hardware cloth (screen) to break up the humus before mixing with soil. Place a heavy-duty framed screen over a large garbage can or a wheelbarrow to catch the sifted compost. Return earthworms found on the screen to the medium and kill cutworms. Make sure all composts are well rotted and have cooled before mixing with indoor soil. For more information about composting, see Let It Rot!, Third Edition, by Stu Campbell, Storey Press, Prowal, VT.
    Some growers mix up to 30 percent perlite into organic potting soil that contains lots of worm castings. Heavy worm castings compact soil and leave little space for air to surround roots. Adding perlite or similar amendments aerates the soil and improves drainage.
     
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Used Soil
Let soil dry.
Screen to separate roots, stems, and foliage from the soil.
Pack in plastic bags.
Remove soil from property.
Dispose of discreetly.
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Growing Medium Disposal
    Disposing of used growing medium can be as big a problem as finding the proper soil. Most soilless mixes and soils contain perlite, which leaves white telltale traces when dumped anywhere. Grow soil is also packed with incriminating cannabis roots. The plug was pulled on more than one grow-show because soil residuals were found in the back yard.
    Dry soil is easier to work and transport. Press and rub dry soil through a 0.25 to 0.5-inch screen to remove roots, stems, and foliage. Screening also transforms the cast-container shape of the soil to an innocuous form. Once the roots are removed, dry, used soil can be bagged up or compacted. Place the dry soil in a trash compactor to make it smaller and more manageable. Do not throw the spent growing medium into your trash can. Remember, it is not a crime for law enforcement in America to dig through your garbage. In fact, picking through a suspected grower’s garbage is a tactic often used by American authorities to secure a search warrant. Remove the depleted soil from the property. Take it to the dump or dispose of it in a very discreet locale. Never throw away the transporting bags with the used soil. Reuse the bags.
    Used indoor growing mediums make excellent outdoor amendments when mixed with compost and garden soil. Do not reuse the depleted soil in outdoor pots. Many of the same problems that occur indoors will happen in outdoor pots.
Grow Medium Problems
    These maladies are caused by growing medium problems but manifest as nutrient problems. The solution is found within the growing medium.
    When water is abundant in the growing medium, roots easily absorb it. Roots use more energy to absorb more water as it becomes scarce. Finally, the point comes when the substrate retains more moisture than it surrenders,and the roots receive no water. A good growing medium readily yields its bank of stored water and nutrients. A poor medium does not pass enough nutrients to a plant’s roots. The more easily cannabis absorbs nutrients, the higher the yield.
    The cation-exchange-capacity (CEC) of a growing medium is its capacity to hold cations that are available for uptake by the roots. The CEC is the number of cation charges held in 3.5 ounces (100 gm) or 100 cc of soil and is measured in milli-Equivalents (mEq) or Centi-Moles/kg on a scale from 0-100. CEC of 0 means the substrate holds no available cations for roots. CEC of 100 means the medium always holds cations available for root uptake. Growing mediums that carry a negative electrical charge are the best.
     
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Visible Signs of Grow Medium Stress
Dry, crispy, brittle leaves
Patchy or inconsistent leaf color
Yellow leaf edges that worsen
Crispy, burnt leaf edges
Chlorosis-yellowing between veins
while veins remain green
Irregular blotches on leaves
Purple stems and leaf stems
Leaf edges curl up or down
Leaf tip curls down
Super-soft pliable leaves
Branch tips stop growing
Leggy growth
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CEC of popular growing mediums measured in Milli-Eq/100 grams
    Compost     90
    Sunshine Mix     90
    Peat moss     80
    Garden soil     70
    Expanded clay     20
    Vermiculite     20
    Perlite     0
    Rockwool     0
    This