Now we come to the confusing part about the guaranteed analysis of commercial fertilizer mixes, Federal and state laws require nutrient concentrations to appear prominently on the face of the fertilizer packages, even though the accuracy of the values is dubious.

Do you think the N-P-K numbers on the label give the percentages of nitrogen, phosphorous, and potassium? Well, yes and no. The scale measures nutrients with different scales. Nitrogen is listed as total combined elemental. Most hydroponic fertilizers break nitrogen into slow-acting nitrate (NO,) and ammonium (NH.). Phosphoric anhydride (P^O,,) is listed as the form of phosphorus, but this figure understates phosphorus content by 44 percent. It gets worse! The balance (56 percent) of the phosphorus molecule is comprised of oxygen, Twenty percent P.,0., is 8,8 percent actual phosphorous. Potassium (K) is listed in the potash form of potassium oxide (K_,0) of which 83 percent of the stated value is actually elemental potassium.

The rest of Ihe mineral nutrients are listed in their elemental form that represents the actual content. Most often, the mineral elements used in the fertilizer formulas are listed in chemical compounds on the label. Look at the fertilizer labels to ensure that the elements, especially trace elements, are chelated and readily available for root absorption. Also, be careful about having too much sodium in your water/nutrient solution. The sodium will block potassium and several other nutrients, causing deficiencies and slow growth.

Nutrients in the United States are measured in parts-per-million (ppm), even though they are expressed as a percentage concentration on the label. The ppm scale is simple and finite-almost. The basics are simple: one part per million is one part of 1,000,000, so divide by one million to find parts per million. To convert percentages into ppm, multiply by 10,000 and move the decimal four (4) spaces to the right. For example: 2 percent equals 20,000 ppm. For more information on ppm and Electrical Conductivity, see Chapter Twelve, "Hydroponic Gardening"

Fertilizers are either water-soluble or partially soluble (gradual-release). Both soluble and gradual-release fertilizers can be organic or chemical.

These are the suggested soluble-salts fertilizer recommendations for indoor cannabis cultivation. The values are expressed in parts per million.

Chemical Fertilizers

The diversity of hydroponic fertilizers is amazing. Local shop owners know which ones work best in the local climate and water. Local store-owners know a lot about the local water and the growers' needs. They are in a perfect position to develop their own nutrient solution or adapt one that works well with their water. A few manufacturers do not do their homework and make bad nutrients. Most manufacturers are conscious and manufacture excellent fertilizers. As always, read the entire fertilizer label and follow the directions.

Soluble-chemical fertilizers are an excellent choice for indoor container cultivation. Soluble fertilizers dissolve in water and are easy to control, and they can be easily added or washed (leached) out of the growing medium. Control the exacting amounts of nutrients available to the plants in an available form with water-soluble fertilizers. The soluble fertilizer may be applied in a water solution onto the soil. In general, high-quality hydroponic fertilizers that use completely soluble food-grade nutrients are the best value. Avoid low-quality fertilizers that do not list all necessary micronutrients on the label.

Chemical granular fertilizers work well but can easily be over-applied, creating toxic soil. They are almost impossible to leach out fast enough to save Ihe plant.

Osmocote1" chemical fertilizers are time release and are used by many nurseries because they are easy to apply and only require one application every few months. Using this type of fertilizer may be convenient, but exacting control is lost. They are best suited for ornamental, containerized plants where labor costs and uniform growth are the main concerns.

Organic Fertilizers

Organically grown cannabis has a sweeter taste, but implementing an organic indoor gar-









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These are the suggested soluble-salts fertilizer recommendations for indoor cannabis cultivation. The values are expressed in parts per million, den requires horticultural know-how. The limited soil, space, and the necessity for sanitation must be considered when growing organically. Outdoors, organic gardening is easy because all of the forces of nature are there for you to seek out and harness. Indoors, few of the natural phenomena are free and easy. Remember, you are Mother Mature and must create everything! The nature of growing indoors does not lend itself to long-term organic gardens, but some organic techniques have been practiced with amazing success.

Most indoor organic gardens use potting soil high in worm castings, peat, sand, manure, leaf mold, compost, and fine dolomite lime. In a container, there is little space to buiid the soil by mixing all kinds of neat composts and organic nutrients to cook down. Even if it were possible to build the soil in a container, it would take months of valuable growing time and it could foster bad insects, fungi, etc. It is easier and safer to throw old, depleted soil outdoors, and start new plants with fresh organic soil.

Organic nutrients, manure, worm castings, blood and bone meal, etc., all work very well to increase the soil nutrient content, but nutrients are released and available at different rates. The nutrient availability may be tricky to calculate, but it is somewhat difficult to over-apply organic fertilizers. Organic nutrients seem to be more consistently available when used in combination with one another. Usually, growers use a mix of about 20 percent worm castings with other organic agents to get a strong, readily available nitrogen base. They fertilize with bat guano, the organic super bloom, during flowering.

An indoor garden using raised beds allows true organic methods. The raised beds have enough soil to hold the nutrients, promote organic activity, and when managed properly, ensure a constant supply of nutrients. The raised beds must have enough soil mass to promote heat and fundamental organic activity.

Dedusting Fertilizers

Several common chemical fertilizers from the hyclroponic industry.

Outdoor organic gardens are easy to implement and maintain. Using compost tea, manures, bulky compost, and other big, smelly things is much easier outdoors.

Organic Teas

Compost teas not only contain soluble organic nutrients diluted in water, but they support a potent elixir that is loaded with beneficial microbes that fight off pests and diseases. For example, a quarter teaspoon of a well-made compost tea holds more than a billion bacteria and at least 15 feet of fungi strands! A good compost tea also contains thousands of different species of protozoa, nematodes, and mycor-rhizal fungi.

Disease-causing organisms are unable to compete with beneficial bacteria and fungi. Beneficial bacteria also work to break down plant residues and toxic materials, plus they improve soil structure and water-holding ability.

The best teas are made from well-rotted compost, because it contains a complex collection of microbes and nutrients. Just make sure the compost pile has heated to 135T (52°C) for at least 3 days to ensure it is free of most diseases. You can usually buy quality compost at the local nursery. If using manure, make sure it has been well-composted.

You can brew the tea in a 5-gallon (19 L) bucket. Add about a gallon (3.8 L) of rotted compost or manure to 4 gallons (15 L) of water. Stir well, and let the mix sit for several days. You can also put sifted compost into a nylon slocking, and submerge tl in the bucket. To stir, simply bounce the stocking around in the water, Stir the mixture gently several times a day to integrate oxygen and remove microbes from the compost. Adequate oxygen keeps the brew fresh. If it starts to smell foul, anaerobic bacteria are present. Add fresh water and stir more often. The good aerobic bacteria re-establish as soon as they have an ample supply of oxygen.

Organic Nutrients Chart

Alfalfa meal has 2.5 percent nitrogen, 5 percent phosphorus, and about 2 percent potash. Outdoor growers use pelletized animal feed as a slow-release fertilizer.

Blood and bone meal are wonderful organic fertilizers, but could transport Mad Cow Disease and other maladies. I can't recommend these with a clear conscience.

Blood (dried or meal) is collected at slaughterhouses, dried, and ground into a powder or meal. Ifs packed with fast-acting soluble nitrogen (12 to 15 percent by weight), about 1,2 percent phosphorus, and under one-percent potash. Apply carefully because it's easy to bum foliage. We advise avoiding use of any dried blood or blood meal that could carry Mad Cow Disease.

Bone meal is rich in phosphorus and nitrogen. The age and type of bone determine the nutrient content of this pulverized slaughterhouse product. Older bones have higher

Organic Cannabis Nutrients
Here are just a few of the numerous fertilizers available for cannabis cultivation.



phosphorus content than young bones. Use bone meal in conjunction with other organic fertilizers for best results. Its lime content helps reduce soil acidity and acts fast in well-aerated soil. We advise avoiding any bone meal that could carry Mad Cow Disease.

Raw, unsteamed bone meal contains 2 to 4 percent nitrogen and 15 to 25 percent phosphorus. Fatty acids in raw bone meal retard decomposition. We advse avoiding any bone meal that could carry Mad Cow Disease.

Steamed or cooked bone meal is made front fresh animal bones that have been boiled or steamed under pressure to render out fats. The pressure treatment causes a little nitrogen loss and an increase in phosphorus. Steamed bones are easier to grind into a fine powder, and the process helps nutrients become available sooner. It contains up to 30 percent phosphorus and about 1.5 percent nitrogen. The finer the bone meal is ground, the faster it becomes available.

Cottonseed meal is the leftover by-product of oil extraction. According to the manufacturer, virtually all chemical residues from commercial cotton production are dissolved in the oil and not found in the meal. This acidic fertilizer contains about 7 percent nitrogen, 2.5 percent phosphorus, and 1.5 percent potash. It should be combined with steamed bone meal and seaweed to form a balanced fertilizer blend.

Chicken manure is rich in available nitrogen, phosphorus, potassium, and trace elements. Indoor growers most often prefer to purchase dry, composted chicken manure in a bag. Use it as a top dressing or mix it with the soil before planting. Often chicken manure collected from farms is packed with feathers, which contain as much as 17 percent nitrogen; this is an added bonus. The average nutrient content of wet chicken manure is as follows: N - l .5%, P - 1.5%, K

- 4%, l< - 1.5%. Both have a full range of trace elements.

Coffee grounds are acidic and encourage acetic bacteria in the soil. Drip-coffee grounds are the richest, and contain about 2 percent nitrogen and traces of other nutrients. Add this to the compost pile or scatter and cultivate it in. Use it as topdressing, but in moderation, because it is very acidic

Compost tea s used by many organic gardeners as the only source of fertilizer. Comfrey is packed with nutrients, and many gardeners grow it just to make compost tea.

Cow manure is sold as steer manure, but it is often collected from dairy herds. Gardeners have used cow manure for centuries, and this has ted to the belief that it is a good fertilizer as well as a soil amendment Steer manure is most valuable as mulch and a soil amendment. It holds water well and maintains fertility for a long time. The nutrient value is low, and it should not be relied upon for the main source of nitrogen. The average nutrient content of cow manure is N - 0.6%, P - 0.3%, K - 0.3%, and a full range of trace elements. Apply at the rate of 25 to 30 pounds per square yard. Diatomaceous earth, the fossilized skeletal remains of fresh and saltwater diatoms, contains a full range of trace elements, and it is a good insecticide. Apply it to the soil when cultivating cr as a topdressing.

Dolomite lime adjusts and balances the pl-l and makes phosphates more available. Generally applied to sweeten or de-acidify the soil. It consists of calcium and magnesium, and is sometimes listed as a primary nutrient, though it is generally referred to as a secondary nutrient.

Feathers and feather meal contain from 12 to 15 percent nitrogen that is released slowly. Feathers included in barnyard chicken manure or obtained from slaughterhouses are an excellent addition to the compost pile or as a fertilizer. Feathers are steamed under pressure, dried, and ground into a powdery feather meal. Feather meal contains slow-release nitrogen of about 12.5 percent.

Fish meal is made from dried fish ground into a meal. It is rich in nitrogen (about 8 percent) and contains around 7 percent phos-

plioric acid and many trace elements. It has an unpleasant odor, causing it to be avoided by indoor growers. It is a great compost activator. Apply it to the soil as a fast-acting top-dressing. To help control odor, cultivate it into the soil or cover it with mulch after applying. Always store it in an air-tight container, so it will not attract cats, dogs, or flies. Fish meal and fish emulsion can contain up to 10 pe-cent nitrogen. The liquid generally contains less nitrogen than the meal. Even when deodorized, the liquid form has an unpleasant odor.

Fish emulsion, an inexpensive soluble liquid, is high in organic nitrogen, trace elements, and some phosphorus and potassium. This natural fertilizer is difficult to over-apply, and it is immediately available to the plants. Even deodorized fish emulsion smells like dead fish. Inorganic potash is added to the fish emulsion by some manufacturers and is semi-organic

Coat manure is much like horse manure but more potent. Compost this manure and treat it as you would horse manure.

Granite dust or granite stone meal contains up to 5 percent potash and several trace elements. Releasing nutrients slowly over several years, granite dust is an inexpensive source ol potash and does not affect soil pH. Not recommended indoors because it is too slow acting.

Greensand (glaucomite) is an iron-potassium silicate that gives the minerals in which it occurs a green tint. It is mined from ancient New Jersey-seabed deposits of shells and organic material rich in iron, phosphorus, potash (5 to 7 percent), and numerous micronutiients. Some organic gardeners do not use Greensand because it is such a limited resource. Greensand slowly releases its treasures in about four years. This is too slow acting for indoor gardens.

Guano (bat) consists of the droppings and remains of bats. It is rich in soluble nitrogen, phosphorus, and trace elements. The limited supply of this fertilizer-known as the soluble organic super bloom-makes it somewhat


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applied too Bat guano has trans formec heavily. Older into the organic super deposits are high bloom fertilizer. in phosphorus and make an excellent flowering fertilizer. Bat guano is usually powdery and is used any time of year as top dressing or diluted in a tea. Do not breathe the dust when handling it, because it can cause nausea and irritation.

Guano (sea bird) is high in nitrogen and other nutrients. The Humboldt Current, along the coast of Peru and northern Chile, keeps the rain from falling, and decomposition of the guano is minimal. South American ¿>uano is the world's best guano. The guano is scraped off rocks of arid sea islands Guano is also collected from many coastlines around the world, so its nutrient content varies.

Gypsum (hydrated calcium sulfate) is used to lower the soil pH, and it improves drainage and aeration. It is also used to hold or slow the rapid decomposition of nitrogen. This is seldom used indoors.

Hoof and horn meal is an excellent source of slow-release nitrogen. Fine-ground horn meal makes nitrogen available quicker and has few problems with fly maggots. Soil bacteria must break it down before it is available to the roots. Apply it two lo three weeks before planting. It remains in the soil for six months or longer. Hoof and horn meal contains from 6 to 15 percent nitrogen and about 2 percent phosphoric acid. We advise avoiding use of any dried blood or bone meal (hat could carry Mad Cow Disease.

Horse manure is readily available from horse stables and racetracks. Use horse manure that has straw or peal for bedding, since wood shavings could be a source of plant disease. Compost horse manure for two months or longer before adding it to the garden The composting process kills weed seeds, and it will make better use of the nutrients. Straw bedding often uses up much of the available nitrogen. Nutrient content of horse manure is N - 0.6%, P -0.6%, l( - 0.4%, and a full range of trace elements.

Kelp is the Cedilla of trace minerals. Kelp should be deep-green, fresh, and smell like the ocean. Seaweed contains 60 to 70 trace minerals that are already chelated (existing in a form that's water soluble and mobile in the soil). Check the label to ensure all elements are not cooked out See Seaweed below.

Oyster shells are ground and normally used as a calcium source for poultry. They contain up to 55 percent calcium and traces of many other nutrients that release slowly. Not practical to use indoors because they break down too slowly.

Paper ash contains about 5 percent phosphorus and over 2 percent potash. It is an excellent water-soluble fertilizer, but do not apply in large doses, because the pH is quite high. Paper ash is also full of toxic inks.

Pigeon manure has a very high concentration of nitrogen but is difficult to find. It can be used in the same fashion as chicken manure.

Rabbit manure is also excellent fertilizer but can be difficult to find in large quantities. Use rabbit manure as you would chicken or pigeon manure. According to John McPartland, rabbit poop is the best. Bunnies rule!

Potash rock supplies up to 8 percent potassium and may contain many trace elements. It releases too slowly to be practical indoors.

Rock phosphate (hard) is a calcium or lime-

based phosphate rock that is finely ground to the consistency of talcum powder. The rock powder contains over 30 percent phosphate and a menagerie of trace elements, but it is available very, very slowly.

Colloidal phosphate (powdered or soft phosphate) is a natural clay phosphate deposit that contains just over 20 percent phosphorus calcium, and many trace elements. It yields only 2 percent phosphate by weight the first few months.

Seaweed meal and/or kelp meal is harvested from the ocean or picked up along the beaches, cleansed of sally water, dried, and ground into a powdery meal. It is packed with potassium (potash), numerous trace elements, vitamins, amino acids, and plant hormones. The nutrient content varies according to the type of kelp and growing conditions. Seaweed meal is easily assimilated by the plants, and contributes to soil life, structure, and nitrogen fixation. It may also help the plants resist many diseases and withstand light frosts. Kep meal also eases transplant shock.

Seaweed (liquid) contains nitrogen, phosphorus, potash, all necessary trace elements in a chelated form, as well as plant hormones. Apply diluted solution to the soil for a quick cure of nutrient deficiencies. Liquid seaweed is also great for soaking seeds and, dipping cuttings and bare roots before planting.

Sheep manure is high in nutrients and makes a wonderful tea. The average nutrient content is: N - 0.8%, P - 0.5%, K - 0.4%, and a full range of trace elements. Sheep manures contain little water and lots of air. They heat up readily in a compost pile. Cow and pig manures are cold because they hold a lot of water and can be compacted easily, squeezing out the air.

Shrimp & crab wastes contain relatively high levels of phosphorus.

Sulfate of potash is normal y produced chemically by treating rock powders with sulfuric acid, but one company, Great Salt Lake Minerals and Chemicas Company, produces a concentrated natural form. The sulfate of potash is extracted from the Great Salt Lake.

Swine manure has a high nutrient content but is slower acting and wetter (more anaerobic) than cow and horse manure. The average nutrient content of pig manure is: N -0.6%, P - 0.6%, K - 0.4%, and a full range of trace elements.

Wood ashes (hardwood) supply up to 10 percent potash, and softwood ashes contain about 5 percent. Potash leaches rapidly. Collect the ash soon after burning, and store in a dry place. Apply in a mix with other fertilizers at the rate of one-quarter cup per 3-gallon pot. The potash washes out of the wood ash quickly and can cause compacted, sticky soil. Avoid using alkaline wood ashes in soil with a pH above 6.5.

Worm castings are excreted, digested humus and other (decomposing) organic matter that contain varying amounts of nitrogen as well as many other elements. They are an excellent source of non-burning soluble nitrogen and an excellent soil amendment that promotes fertility and structure. Mix with the potting soil to form a rich, fertile blend, Pure worm castings look like coarse graphite powder and are heavy and dense. Do not add more than 20 percent worm castings to any mix. They are so heavy that root growth can be impaired. Worm castings are very popular and easier to obtain at commercial nurseries.

Note: The nutrients in organic fertilizers may vary greatly depending upon source, age, erosion, climate, etc. For exact nutrient content, consult the vendor's specifications.

Dilute the tea at the rate of 1 to 5 with water. Add more water to the same bucket, and continue to brew 3 to 4 more batches before starting a new batch.

Make super tea by gently agitating and oxygenating the soup. This will supercharge the tea and add 10 to 100 times more microbes than regular compost tea. The Compost Tea Brewing Manual by Dr. Elaine R. Ingham of Soil

Fill a nylon stocking with sifted, well-rotted compost and soak in a backet for a few days to make a potent fertilizer and plant elixir.

Foodweb, Inc., compares some commercial tea makers, including a bio-blender used in a 5-gallon bucket, 100-, and 500-gallon brewers. The book includes recipes for high bacteria, high fungal, and high mycorrhizal teas. Take a look at the super-compost tea makers at www,soil soyp.com.

Mixing Fertilizers

Always read the entire label, and follow the directions. To mix, dissolve the powder and the crystals into a little warm water, and make sure it is totally dissolved before adding the balance of the tepid water. This will ensure that the fertilizer and the water mix evenly. Liquid fertilizers can be mixed directly with water.

Containers have very little growing medium in which to hold the nutrients, and toxic salt buildup may become a problem. Follow dosage instructions to the letter. Adding too much fertilizer will not make the plants grow faster. It could change the chemical balance of the soil, supply too much of a nutrient, or lock in other nutrients making them unavailable to the plant.

Fertilizer Application

Some varieties can take high doses of nutrients, and other strains grow best with a minimum of supplemental fertilizer. See the chart at


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[email protected]

To get an idea of which strains need a little or a lot of fertilizer, I asked Alan from Sensi Seeds and Henk from Dutch Passion their thoughts. To learn the exact best way to fertilize specific strains, you may need to contact the company that sold you the seeds.

Start with an EC of 1.6 and build it up as needed. The absolute maximum EC is 2.3.

Strains which require high doses of fertilizer:

All the Indicas, with the possible exception of Hindu Kush (a landrace, with less vigor and not as nutrient-hungry as hybrid Indicas). In this case, 'more fertilizer means using the high end of the recommended dosage, not exceeding it.

Twilight, Green Spirit, Khola, Hollands Hope.

Passion iM, Shaman within an EC range of 1.6-2.3

Strains which require medium doses of fertilizer:

Skunkttl, Trance, Voodoo, Sacra Frasca, Cal. Orange, Delta 9, Skunk Passion.

Blueberry, Durban Poison, Purpie/M, Purple Star, Skunk#l, Super Haze, Ultra Skunk, Orange Bud, White Widow, Power Plant and Euforia within an EC range of 1,62.3

Strains which require low doses of fertilizer:

All the Sativa hybrids, with the exceptions of Silver Pearl, Marley's Collie and Fruity Juice (Saliva hybrids, but with a heavy, Indica-dominant bud pattern). In this case, less fertilizer means using the low end of the recommended dosage. Northern Lights #5 x Haze has more open buds in growth pattern, but a lot of floral bulk by weight, so may need normal lo slightly higher levels of nutrient.

Isis, Flo, Dolce Vita, Dreamweaver

Masterkush, Oasis, Skywalker and Hempstar within an EC range of 1.6-2.3. Mazar needs a higher EC during weeks 3 to 5 lo prevent early yellowing of the leaves.

left for recommendations on fertilizing a few varieties. Many fertilizer programs are augmented with different additives that expedite nutrient uptake.

Determine if the plants need to be fertilized: make a visual inspection, take an N-P-K soil test, or experiment on test plants. No matter which method is used, remember, plants in small containers use available nutrients quickly and need frequent fertilizing, while plants in large planters have more soil, supply more nutrients, and can go longer between fertilizing.

Visual Inspection - If the plants are growing well and have deep-green, healthy leaves, they are probably getting all necessary nutrients. The moment growth slows or the leaves begin to

Always use an accurate measuring container.
Low Nitrogen Plant
Pale green leaves signify this plant is low on nitrogen and needs to be fed with an all purpose fertilizer.

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