Marijuana Grower's Handbook

by Ed Rosenthal

  Perlite can be re-used as long as it is rinsed and sterilized and old plant material is removed. It has been used to remediate clay soils, but this is expensive and doesn’t work as well as adding organic material.

  PEAT MOSS

  Peat moss is mined from peat bogs. It consists of layers of sphagnum moss that died and were naturally buried in acidic, anaerobic water.

  Peat moss is probably the most popular container planting material used in North America. It is a key ingredient in most mixes because it holds 15-20 times its weight in water, has excellent buffering ability and is inexpensive. It comes in several sizes, or grades, ranging from very fine, which holds more water because the spaces between the particles are smaller, to larger pieces that provide more airspace.

  Peat moss is very acidic and must be treated with lime to raise its pH. Most mixes have already adjusted the pH but you should give it a pH test yourself. Although it has high buffering capacity, it has no nutrients of its own, so un-enriched mix must be fertilized from the start.

  Peat moss has a chemical relationship with water and as it loses moisture it holds onto the remaining water more tightly, increasing water tension. This makes it more difficult for the roots to absorb water and nutrients. For this reason peat moss based mediums should never be allowed to get dry out. Although they might feel moist, this water may be unavailable to the roots.

  Peat moss is composed of dead plant matter so it contains carbon. Carbon is used by micro-organisms in the soil to build tissue which degrades the peat moss over time. At the same time, it shrinks as it loses its structure. For example, you might have noticed that the soil in a houseplant container shrank over a few months, this happens as the microorganisms use the carbons in the soil. This only presents a problem if the plant is in the mix long term. The compacted mix doesn’t provide enough air to the roots, the roots don’t have as much space to spread out and the plant has less support to hold itself upright. Over a period of a few months this shrinkage does not usually have a noticeable adverse effect.

  A plant has become “rootbound” when the roots have run out of space in the container and cannot spread out further in search of nutrients and water.

  COIR

  Coir, or coco peat, is made from the soft fibers and pith that protect the inner kernel of the coconut. Horticultural coir is made from ripe coconuts. As the fruit ripens the fibers, initially composed mostly of cellulose, change to high lignin content. Lignin, which is also found in wood, resists decomposition better than either bark or peat moss, so it can be used and re-used far longer than bark or peat.

  Coir holds between five and eight times its own weight in water. It also has a fairly high cation exchange rate; the fibers not only absorb water but also chemically hold nutrients and buffer nutrient swings. The air porosity, the amount of air the material holds, depends on the size of the particles and fibers. The finer the fiber, the more water it holds in relation to air. The larger the particle sizes, the lower the initial water retention.

  Another advantage coir holds over peat moss and bark is that it has a higher pH, and is in the acceptable range for growing mediums of 5.8-6.4. It is also a source of potassium as well as iron, manganese, zinc and copper, which it releases gradually. The finer particles, the pith, can be thought of as organic potassium fertilizer with a sponge like molecular structure. It is combined with short fibers that act as an anti-compacting texturizer.

  There is anecdotal evidence that coir possesses fungicidal qualities, which may stem from the lignin or from its surface structure.

  There are many grades of coir based on the particle size and which type of tissue is used. Long fibers have granular material, called pith, attached before processing. Sometimes the two materials are left together but usually they are separated into fiber and pith.

  Each coir processor has its own recipe for a particular combination of pith and fiber. The more pith that it contains, the better its water retention, but the less air it holds.

  Coir chips are another form of coir that is available. These are pieces of coir sliced into cubes ranging from 0.25-0.75” (0.6-2 cm). They are used in place of bark in some soil recipes, as a planting medium for orchids and as a hydroponic planting medium.

  I found that some brands of both coir and coir chips contain residual salt from the manufacturing process or from storage. This has to be removed before use, which is not hard to do. Just soak it in a basin of warm water for about 15 minutes and then press until just moist. Some brands now advertise that they come pre-washed and don’t need to be rinsed.

  BARK

  Chopped or ground bark is often used as an ingredient of planting mixes. The bark’s qualities, such as its water holding capacity and pH level differ by tree variety. The grade of bark and the size of the pieces affect water-holding capacity. The smaller the pieces, the more water they hold and the less airspace between them. Bark contains carbon so it is subject to microbial disintegration. However, this occurs at a slower rate than with peat moss. It also buffers the water nutrient mix absorbing some excess nutrients and releasing them when the solution becomes less concentrated.

  If you are planning on growing a plant that will be kept for five months or more select a bark or coir based soil rather than one made from peat moss.

  Bark is not usually used in hydroponics except in fertigation systems such as capillary mats.

  MYCORRHIZAE

  Mycorrhizae are fungi that live in soil in various forms and share a symbiotic relationship with plants. They are found mostly in the rhizosphere, the area surrounding the roots where plants absorb water and draw nutrients.

  They benefit plants in a number of ways: 1) increased nutrient uptake; 2) exchange of fungal hormones and other manufactures to plants; 3) protection from pathogens and root predators; and 4) better water relations including reduced drought stress.

  This results in increased root vigor and growth with more resistance to disease organisms and drought. Bud quality and yield also increase.

  Top: fungal structures of the roots are shown here. They have been stained blue to show the external mycelium (ext), the internal mycelium (int), arbuscles (arb), and vesicles (ves). Bottom: the AM fungus glomus intradices frequently forms spores in roots. Photos: Priv. Doz. Dr. habil Ewald Sieverding

  TYPES OF MYCORRHIZAE

  Mycorrhizae are divided into two groups, endomycorrhizas and ectomycorrhizas. The ecto’s are associated with forest trees in temperate climate zones and probably have no effect on marijuana growth.

  There are several groups of endomycorrhizae, but we are interested primarily in the arbuscular (named for their “treelike” structure), or AM mycorrhizae. Their hyphae, the center of new growth in AM mycorrhizae, are “root-like or branch-like” structures. Hyphae grow through the plant cell wall and position themselves between the cell wall and the cell membrane. The string-like structures, the arbuscles, colonize new space through growth. As the hyphae mature, vesicles, containing stored lipids saved for leaner times, develop along their length.

  Once it has grown into the cell it has parts both in and outside the roots. Outside it grows a fine network of filaments that serve as an extension of the root hairs. They use electrochemical reactions to dissolve nutrients, especially phosphorus (P), but also the micronutrients, and bring them into the cells. Nutrients get delivered to plants inside the roots and absorb sugars and other plant products released by the roots.

  The AM mychorrhizae produce and release abundant amounts of the glycoprotein glomalin. A glycoprotein is a molecule that combines protein and sugar, which gives it many unique properties. Glomalin is almost 40% carbon (C), and with that much carbon it can host a lot of microorganisms and supply them with one of their needed sources of food.

  Glomalin permeates all the ingredients of soil and organic matter (sand, silt, and clay) and binds them together so they form little clumps of soil granules called aggregates. This adds structure to the soil, and is the first step in nature’s erosion c
ontrol program which keeps stored soil carbon from escaping.

  Mycorrhizae increase absorption in two ways: physical and chemical. Mycelia are smaller in diameter than even the smallest root, so they examine the soil more closely, providing a larger surface area for absorption. Fungi use different methods than plant roots to make soil nutrients available. Their work is most beneficial in nutrient poor soils.

  Beneficial microorganisms inoculate the soil, enhance root growth, and can promote vigorous growth, abundant flowering and enhance the plant's ability to resist disease and fungal attacks. BioBizz PreMix is a dry fertilizer that is mixed into the soil before planting and contains a mixture of organic fertilizers, rock meals and beneficial microorganisms.

  AM Mycorrhizae protect plants from microbial soil-borne pathogens by forming a protective shield around the roots which keeps them healthier. They also produce some warning chemicals that stimulate the plant to prepare for an attack, possibly with protective chemicals, making the roots more resistant to disease organisms and drought because of improved water and mineral uptake.

  CONTENTS OF PAUL STAMETS’ MYCOGROW™ SOLUBLE

  CONTAINS CONCENTRATED SPORE MASS OF THE FOLLOWING:

  Endomycorrhizal fungi Glomus intraradices, Glomus mosseae, Glomus aggregatum, Glomus clarum, Glomus deserticola, Glomus etunicatum, Gigaspora margarita, Gigaspora brasilianum, Gigaspora mono-sporum

  Ectomycorrhizal fungi Rhizopogon villosullus, Rhizopogon luteolus, Rhizopogon amylopogon, Rhizopogon fulvigleba, Pisolithus tinctorius, Laccaria bicolor, Laccaria laccata, Scleroderma cepa, Scleroderma citrinum, Suillus granulatas, Suillus punctatapies

  Trichoderma Trichoderma harzianum, Trichoderma konigii

  Beneficial Bacteria Bacillus subtillus, Bacillus licheniformis, Bacillus azotoformans, Bacillus megaterium, Bacillus coagulans, Bacillus pumlis, Bacillus thuringiensis, Bacillus stearothermiphilis, Paenibacillus polymyxa, Paenibacillus durum, Paenibacillus florescence, Paenibacillus gordonae, Azotobacter polymyxa, Azotobacter chroococcum, Sacchromyces cervisiae, Streptomyces griseues, Streptomyces lydicus, Pseudomonas aureofaceans, Deinococcus erythromyxa

  This soil inoculant contains a wide mix of beneficial fungi and bacteria. It is a general mix that works in a wide range of soil environments and planting mixes. It is designed to enhance plant growth and to protect them from pathogens. The ectomycorrhizae probably have little effect on cannabis. The other organisms in the mix work well in marijuana gardens.

  Plants grown in sterile soils and growth media don’t yield as much as compared with enriched planting mediums and inoculated soils. Add an AM mychorrhizae mix to new soils and planting mediums. AM mychorrhizae take several weeks to colonize a container holding a large plant. However, if you inoculate the plants when they are small, the micro-life will grow with the roots and fill the rhizosphere with organisms that ward off pathogens.

  AM Mycorrhizae and other beneficial organisms are already present in soil or planting mixes that have been used to grow plants for a crop, especially if the last crop was inoculated and the organisms had time to colonize the roots.

  That is why uninfected, inoculated planting mix usually yields a larger harvest on the second and third crops. If you want to change the planting mix, mix some of the old mix into the new medium to inoculate it with the microbes.

  In soil and planting mixes most of the phosphate is bound in water-insoluble minerals. The soil water contains very low concentrations of phosphate. Roots often have a hard time obtaining enough phosphate. The root hairs and associated mycorrhizae have an active transport system to supply the canopy with orthophosphate (H3PO4). Most plants enhance their nutrient uptake capacity using the fungus to extend the surface area of the roots by proxy. This increases the plant’s ability to transport nutrients and to obtain phosphate.

  TRICHODERMA

  Trichoderma fungi are found in nearly all soils. Some species live freely while others colonize the roots. They are variable because cells often contain more than one nucleus and there is a lot of gene mixing, resulting in many unique combinations.

  The fungus grows long filaments, or arms, in their search of food. Trichoderma attack, parasitize and otherwise gain nutrition from other fungi. They use numerous mechanisms to attack other fungi and to enhance plant and root growth. Different strains of Trichoderma control almost every pathogenic fungus for which control has been sought. Each Trichoderma strain has its specialty and controls some pathogens better than others. A particular species may be ineffective against some fungi.

  Some species such as harzianum are used in bio-protectants such as RootShield. Mixed species are often included in endo/ectomycorrhizae mixes.

  BENEFICIAL BACTERIA

  Some bacteria in the rhizosphere also seem to have symbiotic relationships with the roots. Some such as Bacillus subtillus, B.pumlis, B thuringiensis attack pathogens. Serenade® uses B. subtillus as its active ingredient.

  Some species including Pseudomonas cepacia, Serratia marcescens, Erwinia her-bicola, and Phizobium spp. increase the phosphorus supply in the rhizosphere.

  Photo: Sean Mikuriya

  HYDROPONICS

  PLANTING MIX V. HYDROPONICS

  Both planting mixes and hydroponics have advantages and disadvantages. Whether you decide to start a hydro or planting mix garden rest assured that both work, both are capable of producing a high yield, and both provide a satisfying gardening experience. Fertigation is a hybrid between planting mixes and hydroponics and takes advantage of each system.

  Hydroponics offers some advantages over planting mixes. They usually take less physical labor to set up and plants can be grown in smaller containers.

  Post harvest labor, such as removing the planting mix and replanting are much easier hydroponically.

  Plants growing hydroponically usually produce higher yields, faster than those in planting media. However, connoisseurs prefer organically grown to hydroponic weed.

  Hydroponic culture is a bit more exacting than growing using planting mix because there is no media. Organic media such as bark, coir, compost, and peat moss buffer nutrient imbalances so the edge is taken off the peaks and troughs. Hydroponic systems don’t have this buffer so it is up to the gardener to keep the root conditions perfect.

  On the other hand, soil problems that sometimes affect container gardens such as over-watering and soggy conditions do not occur. Nutrient and pH problems can be eliminated since the grower can maintain tight control over the water-nutrient solution. When the solution is kept within the acceptable range there is little chance of lockup.

  Modern planting mixes are made using non-nutritive ingredients including peat moss, bark, coir (coconut husk), rice husks, vermiculite and perlite. All of these ingredients can also be used as planting mediums in fertigation and hydroponic systems.

  Higher quality mixes often include biologically active ingredients such as compost or worm castings, guanos, seed meals, ground rock and parts from dead animals such as blood, bone or feather meal. These mixes support plant growth for a month to six weeks with no additional fertilizers providing the roots have a sufficient area to grow and gather nutrients.

  Some mixes are enriched using inorganic fertilizers. A few brands contain time-release fertilizers designed to support plants for several months. They require little or no additional fertilizer as long as the plants are grown in a large enough container.

  Hydroponics is the method of gardening in which plants are supplied with nutrients through the water solution. Gardeners have a choice of systems to accomplish this. Deep Water Culture (DWC). Drip, Ebb and Flow, Nutrient Flow Technique (NFT), Reservoir and Wick are easy to construct and most of them are also available as commercial units. Another kind of system, Aeroponics, is also discussed here.

  Growstones are a very light substrate made from puffed glass. They hold water within their structure and wick it up through capillary action, and can be used to loosen soil or planting mix or as a hydroponic substrate. They are reusable and easy to steri
lize by boiling.

  Fertigation is practiced in many commercial nurseries growing potted plants. It is a hybrid between planting mediums and hydroponics. That is covered here, too.

  Hydroponic systems vary in their complexity and the amount of care that they require. However, the simplicity of construction or difficulty of maintenance does not infer that the crop will be larger or higher quality. The systems will be discussed in order of complexity.

  Systems fall into one of two broad categories: passive or active. Passive systems such as reservoir or wick setups depend on capillary action to make water available to the plant. Active systems, including ebb and flow, nutrient flow technique (NFT) and deep-water culture, use a pump to provide the plants water and nutrients.

  HYDROPONIC PLANTING MEDIUMS

  Gardeners have a choice of hydroponic mediums. Most are inorganic, meaning that they do not contain carbon molecules, and do not deteriorate quickly.

  A few, such as peat moss, wood chips and bark react with nutrients over time and deteriorate into compost. This usually takes several years, so the reaction in plants that only grow over a three to six month period is minimal. However, these materials need to be replaced over time.

  Perlite and LECA are the most desirable materials and can be used for long periods of time.

  LECA

  LECA (Light Expanded Clay Aggregate) can be used as a media in all types of hydroponic systems including Reservoir, Wick, Deep Water Culture, Nutrient Flow, Aeroponic, Ebb and flow, and Drip systems.