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

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

This ambitious guerrilla grower uses an electric pump to water their plants in Northern California. The pump is wired to the battery in the all-terrain vehicle required to access this remote grow.

Water and fertilize properly and you will be surprised with your results!
     
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    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 for 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#1’, ‘Shaman’ within an EC range of 1.6-2.3
    Strains which require medium doses of fertilizer:
    ‘Skunk#1’, ‘Trance’, ‘Voodoo’, ‘Sacra Frasca’, ‘Cal. Orange’, ‘Delta 9’, ‘Skunk Passion’, ‘Blueberry’, ‘Durban Poison’, ‘Purple#1’, ‘Purple Star’, ‘Skunk#1’, ‘Super Haze’, ‘Ultra Skunk’, ‘Orange Bud’, ‘White Widow’, ‘Power ‘Plant’, and ‘Euforia’ within an EC range of 1.6-2.3
    Strains which require low doses of fertilizer:
    All the Sativa hybrids, with the exceptions of ‘Silver Pearl’, ‘Marley’s Collie’ and ‘Fruity Juice’ ( Sativa 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 to 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 to prevent early yellowing of the leaves.
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    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 turn pale green, it is time to fertilize. Do not confuse yellow leaves caused by a lack of light with yellow leaves caused by a nutrient deficiency.

Always use an accurate measuring container.

Pale green leaves signify this plant is low on nitrogen and needs to be fed with an all purpose fertilizer.

General Hydroponics gives growers specific fertilizer and additive instructions for their products.
    Taking an N-P-K soil test will reveal exactly how much of each major nutrient is available to the plant. The test kits mix a soil sample with a chemical. After the soil settles, a color reading is taken from the liquid and matched to a color chart. The appropriate percent of fertilizer is then added. This method is exact but more trouble than it is worth.
    Experimenting on two or three test plants is the best way to gain experience and develop horticultural skills. Clones are perfect for this type of experiment. Give the test plants some fertilizer, and see if they green up and grow faster. You should notice a change within three to four days. If it is good for one, it should be good for all.
    Now, it has been determined that the plants need fertilizer. How much?