Marijuana Grower's Handbook

by Ed Rosenthal

  The cool water produced by the ice is beneficial to the roots. The soil is hotter than the ideal temperature in the low 70s F (20-23˚ C). The gradual melt will cool the soil enough for the roots to enjoy a reprieve from the ultra-hot and to drink up over a period of time. This method also gives the soil time to absorb the liquid as the ice melts rather than have it pool and flow away.

  Remember—one gallon (3.71 = 3.6 kg) of ice weighs eight pounds (3.6 kg).

  COMMUTER PLANTS

  My plants just started budding and I live in a place where it freezes at night in September. I have been bringing them in at night so frost won’t damage them. Is this necessary? The buds are about a half-inch long this morning.

  It’s good that your plants are in containers and you have the luxury of moving the plants into sunlight each day and into the comfort of a dark garage each evening. You are doing the right thing. Freezes inhibit bud production and ripening. Removing the plants to warmer quarters keeps them on course even as the weather changes.

  Make sure to bring them outside and back inside at the same time each day, or at least to give them as much sunshine as possible as the days shorten.

  Good ventilation to the outside may be enough to keep the air moving. Place fans at or below the canopy level to push cool air through the canopy. Another solution is to run overhead fans in reverse so that air is pulled up, rather than pushed down.

  Be sure to screen any air intake fans, to prevent intrusion of pests from outside.

  AIR QUALITY

  Besides temperature and CO2 content, other things to consider about the air in your garden, include dust content, electrical charge, and humidity.

  DUST

  The dust content of the air affects the efficiency of the plant’s ability to photosynthesize. Although floating dust blocks only a small amount of light, dust accumulated on leaves blocks large amounts.

  “Dust” is actually composed of many different-sized solid and liquid particles that float in the gaseous soup of the atmosphere. The particles include organic fibers, hair, other animal and vegetable particles, bacteria, viruses, smoke, and such odoriferous liquid particles as essential oils and water-soluble condensates. Virtually all dust particles have a positive electrical charge because they are missing an electron, which causes them to float in gasses.

  Dust particles precipitated from the air change the charge using negative ion or ozone generators.

  Wash off dust from leaves using a fine mist spray. Be careful when using water sprays around hot lights. If even a little water hits the hot glass of the lights, the bulbs can shatter. Before spraying shut the lights off and let them cool down.

  NEGATIVE IONS

  Negative ions can precipitate dust, spores, and odors. (See Security.) The air’s electrical charge affects plant growth and animal behavior, as well as the strength of odors. The clean, fresh-smelling air that follows a rain is due to the extra negative ions left in the air by falling water. Air in verdant, unindustrialized areas and near large bodies of water, is also negatively charged; electrons float in the air loosely attached to oxygen molecules. In industrialized areas or very dry regions, the air is positively charged because molecules are missing electrons. Negative ions jump from oxygen carriers to the electron deficient molecules, neutralizing them and causing them to precipitate.

  Negative ion enrichment creates a few readily observable effects:

  •Plants in negative-ion environments grow faster than those in positively charged ones.

  •Negative ions precipitate dust particles, hair, and dander from the air, so there are fewer bacteria and fungus spores floating around.

  •Negative ions eliminate unwanted odors, which are positively charged particles in the air. Increasing negative ions causes the odor-carrying particles to precipitate. With enough negative ions, even a room filled with pungent, flowering sinsemilla becomes odorless.

  Many firms manufacture negative ion generators, ionizers, or ion fountains. These units are inexpensive, safe, use minuscule amounts of electricity, and are recommended for vegetatively growing gardens during the first weeks of flowering. However, when they are used in the garden itself during the last weeks of flowering they eliminate odors in the garden and the plants.

  Most modern ion generators capture the particles they precipitate in a cleanable, reusable filter. A few cheaper models have no provision for capturing the greasy precipitate. Since the thick film of grime usually lands within a two-foot (0.6 m) radius of the ion fountain, placing newspaper around the unit is a convenient way to collect the residue. You can make a precipitator by grounding a sheet of aluminum foil to a metal plumbing line or grounding box. Attach an alligator clip and a piece of wire to the foil and grounding source. When the foil gets soiled, replace it.

  To preserve the classic, bag-busting aroma of your crop, don’t use negative ions in the flowering room during the last three weeks of flowering. Negative ions interact with the odor molecules not only in the air but also those present on the plant that are not fully protected by the trichome membrane. The negative ions neutralize them so they are odor-free. The terpenes inside the membrane are unaffected, so a pinched bud still releases a powerful aroma. But for best results, use ion generators during the last three weeks of flowering only in the rooms surrounding the garden room, not inside.

  PART 11 QUICK POINTS: WHAT ARE PLANTS AND WHAT DO THEY WANT

  MARIJUANA PLANT LIFE CYCLE

  Seeds contain the embryos of plants and when they come in contact with water they begin to germinate. A pair of embryonic leaves, cotyledons, emerge and the plant begins to photosynthesize. At the same time, roots grow into the planting medium to gather water and nutrients.

  Photosynthesis is the process in which plants capture the energy from light and use it to power a series of biochemical reactions. Carbon dioxide from air and water are combined to produce sugar and release oxygen into the atmosphere. Sugars created in the process fuel the plant’s metabolism; it’s energy for life processes.

  Cannabis is considered a short-day plant that flowers in the fall. The processes of germination, seedling growth, vegetative, flowering and ripening happen over a 100 to 130-day time period.

  Marijuana plants are dependent on their environment for the materials and energy it supplies. There are five factors that affect marijuana growth: light, CO2, nutrients, water, oxygen, and temperature.

  The plant’s ability to fully utilize any of the five factors is dependent on the other four. For this reason these five factors are called the limiting factors.

  The limiting factor, or the factor that is not supplied adequately, determines the rate of growth. Growth slows or stops when that factor is not adequately supplied.

  Things to Know

  •Red light from 660 to 680 nm prevents flowering. A short burst of far-red light at 730 nm after lights out or dusk accelerates flowering.

  •Chlorophyll is the pigment where photosynthesis takes place. It converts CO2 and water using the energy from light into sugar.

  •Marijuana potency is determined, for the most part, by genetics. It can be increased or decreased by environmental factors.

  LIGHT

  Plants use the energy they get from light to make sugar from water and carbon dioxide through the process of photosynthesis.

  Red and blue are the wavelengths plants use most efficiently because chlorophyll, where light energy is used to make sugar, absorbs light primarily in the red and blue spectrums.

  In addition to using light for energy, plants use it to regulate growth. Light determines the direction of growth (heliotropism) as well as whether the plant will elongate or grow stout stems. (Infrared light promotes elongation; red and blue light promote stout stems.)

  The amount of THC a plant produces increases with the amount of UVB light a plant receives. This light can be provided to indoor plants with proper lighting. Outdoors, the amount of UVB light is highest during the summer.

  Indoor gardeners use fluoresce
nt, metal halide, high-pressure sodium and LED lamps. The indoor gardener can ensure their plants are using the lights provided to their full potential by using a light meter. A light meter lets you double check your calculations and ensure that you have set up a garden with light distributed evenly throughout.

  Mixing light sources such as fluorescents or LEDs with high intensity discharge lamps helps the garden because together they provide more light and can fill in the partially shaded areas.

  Each lamp has an electrical system that requires conversion to a higher voltage than is delivered through the electric grid. The ballast converts the building current to the appropriate voltage.

  Things to Know

  •Sativas, and to a lesser extent sativaindica hybrids, require the most light because they evolved below the 30th parallel, near the equator. Because indicas evolved in northern latitudes they are best for low-light gardens.

  •The better measure of light in relationship to usefulness to plants is Photosynthetically Active Radiation or PAR light. PAR light, however, does not measure far red and UV light, both wavelengths that marijuana uses for growth.

  NUTRIENTS AND FERTILIZERS

  Once the plant is in the ground or container, the two easiest and most reliable ways to meet the plant’s needs are to use a prepared hydroponic fertilizer or an organic water-soluble fertilizer. Hydroponic fertilizers are blended as balanced and complete nutrient formulas. Most non-hydroponic fertilizers contain only macronutrients—nitrogen (N), phosphorus (P), and potassium (K). Organic fertilizers, such as fish emulsion, guanos and manures, and many blends of organics, contain additional trace elements found in the organic matter from which they are derived.

  Demand for critical nutrients (N, P, K) varies with the plant conditions and life cycle of each plant.

  Plants grown in soil mixes can typically get along using basic fertilizers such as compost and manure, while plants grown in soil-less mixes require micronutrient enrichment in the form of mineral nutrients in the water. Plants grown in a nutrient-rich medium with—compost, manure, or time-release fertilizers—may need no additional fertilizing when planted in a large enough container or outdoor garden. Additional nutrients can be administered in supplemental amounts if the plants begin to show deficiencies.

  Many nutrient deficiencies are the result of minerals being locked up because of a pH imbalance. Rather than just adding more nutrients, check the pH first and adjust accordingly.

  If added nutrients cure a deficiency, the plant usually responds in apparent ways within one or two days. However, if the gardener over-fertilizes, the plant will overdose, which becomes apparent quickly (within hours or less), resulting in wilting followed by death. Leaves and other parts that were slightly discolored may return to normal, although plant parts that were severely damaged or suffered necrosis will not recover. The most dramatic changes should be monitored in the new growth.

  Things to Know

  •A plant’s ability to absorb nutrients is affected by the temperature, among other factors. Under high light, hot conditions, to prevent thinning of stalks, plants should be given 10 – 20% less nitrogen. Under a cool or cold regimen increase the nitrogen by 10 – 20%.

  •Demand for nutrients varies by growth stage. Marijuana uses more nitrogen during the vegetative cycle, more phosphorous during flowering, and the most potassium after fertilization, to aid seed production.

  •Over-fertilization occurs when a plant absorbs more fertilizer than it needs. Three common indicators are that the leaves turn a darker green than usual, the leaf tips brown, or the leaves curl down.

  •Fertilizer overdoses happen within hours, sometimes sooner. They occur when the nutrient content of the rooting medium has a higher concentration of dissolved solids than the plant itself, rendering the plant unable to draw water, which causes wilting.

  WATER

  The mineral, carbon dioxide, and oxygen content of water varies substantially, and affects your plants. Mineral content is often referred to as dissolved solids, which are expressed as parts per million (ppm) and can be tested approximately by measuring the electrical conductivity (EC) of the water.

  A reading of 125-150 ppm for your water is a good starting point.

  The pH is a measure of acid-alkalinity balance and is measured on a scale of 0-14, with 0 the most acid, 7 neutral, and 14 pure alkali. Every point increase or decrease on the pH scale reflects a 10-fold change in acidity or alkalinity.

  Most nutrients that plants use are soluble only in a limited range of acidity. Solubility also depends to some extent on the type of soil, planting mix, or hydroponic medium.

  Should the water solution in the soil become too acid or alkaline, the nutrients dissolved in the water precipitate and become unavailable to the plants. When the nutrients are locked up, plant growth is slowed.

  For absolute control of the planting medium, test the pH weekly. Water should always be pH adjusted after nutrients are added, since they affect its balance.

  Things to Know

  •The three key measures of water composition are alkalinity (the ability of water to buffer acids), its pH (a measure of the acid-alkalinity balance) and its content of dissolved minerals.

  •Most nutrients plants use are soluble only in a limited range of acidity, from about 5.5 to about 6.5 in mineral soil and 5.6-6.3 in hydro medium.

  CO2

  CO2 is one of the two raw materials required for plants to photosynthesize. (Water is the other.) Cannabis uses CO2 only in the presence of light. Photosynthesis occurs immediately after the plant receives light.

  The amount of CO2 in the air has a profound effect on the rate of photosynthesis and plant growth. Photosynthesis speeds up when CO2 in the air increases, as long as there is enough light to power it. Conversely, when CO2 content of the air falls, photosynthesis slows to a crawl and virtually stops at a CO2 concentration of around 200 ppm, no matter what the other conditions. Lacking CO2, plants continue respiration for a short time, until their sugars are used up; then their metabolism slows down to conserve energy. Only when more CO2 is available can the plant continue the process.

  Increasing CO2 concentration without increasing light intensity does not result in a higher rate of photosynthesis. By increasing the light intensity you can encourage your plants to absorb even more CO2 increasing growth and yield.

  The most convenient way to supplement your grow space with CO2 is by using a meter, regulator and tank kit. Other ways to bring CO2 into the grow space include water heaters and other gas appliances, dry ice, chemical reactions, and biological processes such as composting, fermentation, and animal respiration.

  In most systems, CO2 should be released just above the plants. The gas is heavier and cooler than the air so it sinks. As it flows downward, it reaches the top of the canopy first. This is where most of the light touches the leaves and where most of the CO2-consuming photosynthesis takes place.

  Outdoor plants growing in the bright light of summer grow heavier and faster when supplemented with CO2, and produce a higher yield.

  Roots do not need CO2 because they do not photosynthesize and have no use for it. Plants obtain CO2 through the leaf stomata. CO2 in the soil or water can pose a problem because it can drive out much needed oxygen.

  CO2 is not dangerous. It is a nonflammable gas. It is non-toxic at the low levels growers employ.

  Things to Know

  •Plants obtain oxygen in three ways: oxygen released during photosynthesis, oxygen in the atmosphere, and oxygen dissolved in water, which is absorbed by the plant’s stomata and roots.

  •It is impossible for your plants to “overdose” on CO2. In fact, your plant can thrive from supplemental CO2 as long as adequate light and temperature conditions are met.

  TEMPERATURE, HUMIDITY, & AIR QUALITY

  Marijuana grows well in moderate temperatures, between 70° and 85° F (21°-29° C). Both high and low temperatures slow marijuana’s rate of metabolism and growth. The ideal temperature for you
r plant is tied to light conditions. As more light is available, the ideal temperature for normal plant growth increases. At temperatures below 60° F (15° C), photosynthesis and plant metabolism slow, stopping growth as it waits for better conditions.

  Plants kept at a constant temperature are likely to grow stouter, sturdier stems and have denser bud growth. At temperatures below 60° F (15° C), growth slows as plants wait for better conditions.

  Marijuana plants are very hardy and survive outdoors over a wide range of temperatures, even including extremely hot weather, up to 120° F (29° C). However as the temperature rises from the high 70s into the low 80s (20-25° C), plants spend more energy staying cool and maintaining faster cell metabolism.

  When taking the temperature of a garden, the specific area of interest is in the uppermost foliage of the plant canopy. The space between the plants may be cool, but most important is the temperature of the canopy under the lights where the plants are producing new growth.

  Root temperature is just as important as canopy temperature. When a plant’s roots are kept warm, the rest of the plant can be kept cooler with no damage. Cold floors or earth slow germination and growth. Cold temperatures also encourage more of the plants to develop as males. Additionally, water temperature should be adjusted to balance out the air temperature.

  Besides temperature and CO2 content, the air quality in your garden is affected by dust content, electrical charge, and humidity. Cannabis grows best in an environment that is mildly humid 40-55%.

  Things to Know

  •Water temperature should be adjusted to balance out the air temperature. If the air is warm (over 75°F, 22°C) the water should be no more than 70°F (20°C). If the air is over 90°F (30°C) the water can be lowered from 70°F to 65° (from 20°C to 18°C).

  •It is important to keep the canopy cool to maintain photosynthetic growth. In high temperatures outdoors, use a fine spray of water from a patio mister, or something similar. Indoors, there are many ways to keep the canopy cool—using air or water-cooled lights, running the lights at night, venting the garden with filtered air, and air conditioning or air cooler units.