Marijuana Grower's Handbook

by Ed Rosenthal

  •Water holding crystals can be mixed into the soil. These crystals expand to many times their dry size as they soak up water when soil is irrigated. They release the water as the soil dries. This increases the soil’s total water-holding capacity.

  •Organic mulch placed on top of the soil layer lowers the evaporation rate: the barrier between the moist soil and heat and light eliminates most evaporation. The soil stays moist longer and the top layer of soil stays moist longer.

  •Inorganic soil covering like old rugs placed reverse side up keep soil cool, stop erosion burrowing by pesky mammals and most importantly, keep the soil moist. They work extraordinarily well.

  UNDERGROUND WATER RESERVOIRS AND “TILING”

  You have dug the planting hole or trough or are about to construct a raised bed, but ordinarily a good portion of the water sinks below the root zone and is wasted. There are several ways of keeping the water available to the roots.

  A tray or plastic lining holds water. Place rockwool or gravel at the bottom to prevent it filling with soil. The tube is used as a water level indicator; it rises when the water is high and sinks when water level drops. The roots grow into the reservoir and have a large source of water.

  Not only do these methods conserve water, they also keep the soil fertile since the water doesn’t drain away after dissolving nutrient salts. The fertilizers in enriched water stay longer in the root zone.

  For thousands of years farmers have preserved water at the root level by placing tiles several feet under the soil surface so that the water is trapped and must move laterally rather than vertically to drain. The modern version of this is to place a layer of impermeable plastic at the bottom of the hole or raised bed.

  Planting in holes or beds is a labor-saving alternative to tilling the soil of the entire area. For planting in holes, the area to be dug can range from 1' to 10' wide and 1' to 4' deep. Digging can be facilitated using a power auger, a post-hole digger, or a backhoe. Once the hole has been dug, adjust the native soil or replace it with topsoil or a landscape mix.

  An agricultural tray or a kiddie pool can be placed at the bottom of the hole or raised bed and filled with gravel; it will collect and hold a large amount of water. An impermeable plastic tarp can also be used. Make sure that the plastic reaches 6-8" (15-20 cm) up the sides of the hole to create a “tray."

  Capillary action draws the water up as it used. Using this method, virtually all the water usually lost to draining can be preserved.

  To make sure this is taking place and to guide the roots to the pool of water, place wicks made of 5⁄8” (1.5 cm) nylon braided rope stretching from the reservoir to the top of the soil. The roots grow down into the pool or tray.

  Underground, plastic deteriorates much more slowly than at the surface, where it is attacked by light and other harsh environmental conditions. Once the system is in place it can be used for years and the planting mix will just need supplements to retain and improve its fertility.

  GROWING IN CONTAINERS

  Old rugs, placed upside down so they have a more “organic” look than pink or burgundy, keep weeds from growing and keep the ground moist by absorbing light’s energy and preventing evaporation. They are heavy enough to stay in place.

  Until the last third of the 20th century most planting mixes were composed of loam mixed with sand, compost or humus and perhaps some peat moss. These mixes usually worked well but they brought several problems with them. They were heavy, which made them and the plants they held costly to ship and inconvenient to handle. Secondly, loam is mined topsoil that may include hidden pests and diseases unless it is pasteurized. The use of loam also presents ecological problems.

  Marijuana grows very well in containers, both indoors and out. They require more care and attention than plants growing in soil. Rather than working with the natural environment, or at least a semblance of it, when plants are growing in containers you control the space the roots have, as well as the water conditions and nutrients. Container size plays a roll in determining the growth, final size and yield of the plant.

  INDOORS

  Indoors, plants growing in containers should have a root space of 3-5 gallons (11-19 l) per sq. foot (.09 sq. m) of the canopy space the mature plant is to occupy. Sixteen of these containers fit in a 4’ x 4’ (1.21 x 1.21 m) space.

  These 3-5 gallon (11-19 l) pots provide the roots with enough space to spread out and down throughout the container without becoming “rootbound,” although the roots provide for a canopy of the same width as the roots. Sometimes the plant canopy spreads up to a third larger than the diameter of the roots. The plants stay in the container for only a few months because they are forced to flower as soon as they grow into the canopy, a matter of weeks. The plant will retire in 10 to 12 weeks. Given an enriched medium or nutrient/water mix the roots will be able to meet all the plant’s requirements.

  If plant limits are not a problem, then you can grow plants close together so each plant grows a single stem and is then forced to flower. This system, called “sea of green (SOG),” requires very little time spent in vegetative growth. The plants spend most of their lives flowering. Using this system you can place 64 6” (15 cm) containers in the space. Each container should hold 3-4 quarts (3-4 l) of planting mix.

  Containers with handles make it easy to move plants around with the sun. Smart Pots are reuseable and lightweight. Because the container is fabric, ample supply of air reaches the roots and they do not become rootbound.

  Woven plastic planting bags: handles make it much easier to move the bags. The rectangular bottom helps them stay upright.

  If you are planning to grow plants with a larger canopy, place them in larger containers. Usually as the width of a container grows, the plant’s width does too. With seed planted, taproots penetrate vertically and provide extra support and a healthy supply of nutrients through its network of lateral roots. Container height is more important for seed plants than for clones. Clones don’t need the height. Rather than using planting containers, you might find 10-12” (25-30 cm) tall trays more convenient because they are shorter and save space and planting mix.

  A garden the same size with four plants each set in a container that measures 2’ (60 cm) square provides a large enough area of planting mix to support the plants, their numerous buds, and the extensive root systems that provide all the water and nutrients the plant needs.

  A single plant in a 16 sq ft (1.5 sq m) garden can be placed in a 3’ (90 cm) square container with planting mix 12 in (30 cm) deep.

  These containers might seem large and you may feel you can grow plants in smaller containers, but treating the roots generously and letting them stretch out helps the plant reach its full potential so it grows the biggest buds and produces the biggest yields.

  Instead of using containers you can use a planting bed. It’s just like a raised bed, but indoors. The plants grow directly in the planting mix without the restrictions of containers. Each root system has more total space to explore and grow allowing it to gather more water and nutrients. Once it’s set up you don’t have to pot or un-pot planting mix. Just freshen it up between crops and you are ready to go again.

  Soil bags can be laid flat for use as a planting container.

  This Trainwreck was placed in a 30 gallon plastic bag filled with used planting mix. The bottom was cut open for drainage. The roots followed the water into the soil.

  CONTAINER FACTS

  •Rectangular containers hold more than circular containers of the same size.

  •Containers must be able to drain well. Avoid containers with holes on the bottom in favor of holes on the side if the containers are to be placed on a solid surface. Bottom holes are easily blocked. Instead use containers with holes on the sides.

  •Unconventional containers are fine to use. Adapt square and rectangular shaped plastic trays and containers by creating drainage holes.

  •Plastic grow bags come in all sizes. They work well indoors and out, and are lig
htweight and inexpensive. Gusseted bags are the best ones to use. They are like paper shopping bags, with a rectangular bottom. Make sure they have drainage holes that are appropriately placed.

  •Bags and containers are much easier to move and make gardening much less fatiguing when they are equipped with handles.

  •Large containers can be moved with a container handler, hand truck or heavy-duty wagon.

  •You can use planting mix in the plastic bag it came in as the planting container. Set the bag upright for good drainage.

  •For bigger plants place two bags on top of each other horizontally. Remove the plastic separating them. Place holes along the bottom side of the bottom bag to assure drainage. If you want the plant roots to get rain, open the top bag so it can soak in. If not, conserve water by keeping the top covered. Water the plant manually or using a drip emitter.

  •Mount large containers on wheels for easy placement and reorganization.

  TIPS FOR OUTDOOR CONTAINERS

  •Light beating down on a container can raise the temperature of the soil and roots causing tissue damage to the plant. Black containers are the worst because they absorb all the light. Containers wrapped in light colored material such as cloth, paper or plastic, painted white or pastel or placed in a basket won’t get hot.

  •Covering containers with white plastic helps slow evaporation.

  •If the containers are stationary let the roots migrate from the container to the ground. The new roots will supply the plant with more water and nutrients.

  PLANTING MIXES

  The most important considerations of planting mixes are their texture, air and water holding capacity. The mixture should drain well so that oxygen, required by the roots, can fill the empty spaces.

  Mixes with fine particles are good candidates for small size containers, perhaps up to 6-inch diameter. However they may become soggy and waterlogged in larger containers, creating anaerobic conditions, deadly to the roots.

  A moist potting mix with a good texture should form a clump if is squeezed into a fist; then with a slight poke the clod should break apart. If it sticks together it should be amended with ingredients that loosen it up.

  These include:

  •coir

  •perlite

  •vermiculite

  •compost

  High quality commercial potting mixes almost always have good texture and to provide plants with high amounts of water and air.

  Most gardeners, even old timers who used to swear by their own mixes, have switched to ready-mixed planting mix. Whether they choose a totally non-nutritive or a fortified mix enriched with organic nutrients the producer has adjusted its pH and nutrient values to assure healthful growth. In side to side tests some mixes perform better than others, so it is worthwhile to test different brands in side by side experiments.

  Some gardeners would still prefer to grow their own soil from basic ingredients.

  There are two main advantages to growing in a planting mix rather than hydroponically. The first is that most of the ingredients of planting mixes, bark, coir and peat moss, are all carbon based and chemically active so they act as a buffer for fertilizers and nutrients. They catch and hold excess nutrients dissolved in the water/nutrient solution and release them when the nutrient water solution becomes less concentrated. For this reason they are more forgiving than hydroponics, where there is little or no interaction between the medium and the water.

  The second advantage of planting mixes over hydroponics is that plants in mixes can be fed organic nutrients. This is very difficult to do hydroponically because the nutrients tend to ferment. Aside from the sensitivity that some people have to inorganically produced ingestibles or smokables, there is a general consensus that organically grown buds have better flavor and aroma than hydroponically grown. This hasn’t been tested in a double blind study, but plants fed inorganic fertilizers sometimes have a distinctive “chemical” taste, especially if they have been overfed or the medium as not been flushed.

  Commonly used ingredients are:

  VERMICULITE

  Vermiculite is a very lightweight processed mineral that is often used as an ingredient in planting mediums. It absorbs and holds water, buffers nutrients, and provides space for oxygen to get to the roots.

  Vermiculite rock is mined and then exfoliated by heating it to 1650-2010° F (900-1100° C). It expands for the same reason popcorn pops; water trapped inside the mineral turns to steam and explodes, forcing the layers of aluminum silicate to separate. The rock expands to 11-15 times its original size. This process also sterilizes it.

  Vermiculite has a composition similar to mica; a thin layer of oxygen, magnesium, and iron atoms holds flat layers of aluminum-silica together. Looking at a piece of it, you can see the layers. This arrangement, with wide gaps between the layers, allows the mineral to absorb and hold water and gives it a large surface area to bond with nutrient minerals, buffering the water-nutrient solution.

  Over time, vermiculite breaks down as the layers, which have tenuous bonds, start to break free. The physical structure, with wide spaces between layers, is eliminated, so there is less space for air. For this reason vermiculite is not a good choice as a single medium in large containers.

  This raised bed was 6’ (180 cm) square, and 1’ (30 cm) tall. The bed gave the roots, and the plant, a great head start.

  Despite myths to the contrary, vermiculite is not inert. Aside from holding nutrients it slowly breaks up as it releases its magnesium and iron atoms. By interacting with the water/nutrient solution, and providing a convenient space for colonization, the medium promotes thriving rhizosphere activity. Although it is active, it does not contain any nutrients. When it is used alone all of the plant’s nutrient requirements must be met using a water/nutrient solution.

  Because there is natural variation in its makeup, vermiculite pH ranges from about 6-9. Usually it is near neutral. It is sold in several grades, which are based on the size of the particles.

  Seeds and cuttings—Vermiculite is sterile and holds lots of water, but still allows air to penetrate, so it promotes growth of seedlings and clones when using a fine grade. Roots grow into a healthy rootball in it.

  Small Containers—The coarser grades of vermiculite are excellent for small containers, up to about 6” (15 cm). It promotes root growth because the medium is loose and porous and gives the roots access to both water and air.

  Planting Mixes—Vermiculite is used as an ingredient in many planting mixes because of its water/air holding qualities and because it is lightweight. When considering planting mixes for large containers, especially when they are to be moved, weight becomes a consideration. Vermiculite helps lighten the mix.

  Should you find a planting mix is too “hot” (it contains too much nutrient), you can mix in vermiculite to dilute the concentration.

  Hydroponics—Vermiculite contains virtually no nutrients so it is an excellent planting medium ingredient for hydroponics. It is usually mixed with perlite or wood chips.

  PERLITE

  Perlite is a mined volcanic glass-like mineral similar to obsidian which melts at 1560-1740° F (850-950° C). Water held in the rock turns to steam and causes the liquid to foam. It expands up to twenty times its original volume and has a structure with many tiny, closed cells or bubbles. The resulting snow-white particles are sterile, inert and have a neutral pH. The hard pieces remain stable for years. They wick water through capillary action.

  The particle surface is covered with tiny craters that create an extremely large surface area that can hold the water/nutrient solution. Passages in the structure also hold pockets of air and promote drainage.

  Perlite comes in various sizes, or grades, that range from very fine to pea sized gravel. The amount of water adsorbed on the surface of perlite is a function of particle size. Coarser perlite particles adsorb less water than the finer grades. Generally the smaller sizes are used in smaller containers. Larger sizes are used in larger containers and maint
ain porous spaces for air. However, various sizes are sometimes included in soil mixes to customize water-holding capacity.

  Because it retains air pockets when it is irrigated, the granules float.

  Perlite's bright white color protects seeds by keeping them cool and moist even when placed under bright sunlight. It reflects light back to plant foliage which further enhances growth.

  Propogation and Seed Cultivation—Fine grade perlite makes a good medium for seed starting and cloning because it maintains a uniform moisture level. Excess water drains so there is no waterlogging. Since the perlite doesn’t form a chemical bond with the water, water tension doesn’t increase as long as there is moisture present. This helps young plants overcome environmental stresses.

  Perlite clings to roots and root hairs so they can form a rootball. This reduces transplant shock.

  Planting Mixes—Perlite is often used as an ingredient in planting mixes. Different sizes are used to adjust water-holding capacity and provide aeration. It keeps the mix lightweight and provides it structure since it does not deteriorate.

  Hydroponics—Perlite’s capillary action and fast drainage are ideal qualities for hydroponic mediums. It makes water management self-regulating. It is inert so it doesn’t interfere with fertilizer and nutrient programs.

  Perlite can be used in a single ingredient planting medium in many hydroponic systems including wick, reservoir, drip and constant flow. However, because its lightweight granules shift position in ebb and flow systems, plants must be supported using staking or another technique.

  Its ability to retain water, provide air spaces, its neutral pH, and non-reactive qualities make it an excellent medium.

  Perlite is often used as an ingredient in hydroponic and soilless mediums with vermiculite, peat moss or bark. Part of its usefulness is that it retains its structure as contrasted with peat moss, which deteriorates as it reacts with soil degrades into compost, and vermiculite that gradually loses its structural integrity and collapses.