PLANT FOOD AND NUTRIENTS - Cannabis Growing Guide
Plant foods have 3 main ingredients that will be the mainstay of the garden,
Nitrogen, Phosphorus, and Potassium. These 3 ingredients are usually listed on
the front label of the plant food in the order of N-P-K. A 20-20-20 plant food
has a Nitrogen level of 20%.
Secondary nutrients are Calcium, Sulphur and Magnesium. In trace quantities,
boron, copper, molybenum, zink, iron, and manganese.
Depending on stage of growth, different nutrients are needed at different
times. For rooting and germination, levels of high P nutrients with less N/K are
needed. Vegetative growth needs lots of N, and human urine is one of the better
sources, (mix 8 ounces to 1 gallon water), although it is not a complete
fertilizer unto itself. 20-20-20 with trace elements should do it; I like
Miracle Grow Patio food. Watch for calcium, magnesium, sulfur and iron levels
too. These are important. One tablespoon of dolomite or hydrated lime is used
per gallon of growing medium when a hydroponic medium is first brought on-line,
to provide nitrogen, calcium and magnesium. Epsom salts are used to enhance
magnesium and sulphur levels in solution.
Tobacco grown with potassium nitrate burns better. Plant foods with PN (P2N3)
are foods such as Miracle Grow. This is an excellent fertilizer for vegetative
growth, or through the flowering cycle as well. Consider however, potassium
nitrate is also known as Salt Peter, and is used to make men have less sexual
desire or impotent, such as in mental institutions. So if certain plants are
destined for cooking, you might use Fish Emulsion or some other totally organic
fertilizer on these plants, at least in the last weeks of flowering.
Most hydroponic solutions should be in the range of 150-600 parts per million
in disolved solids. 300-400 ppm is optimum. It is possible to test your solution
or soil with a electrical conductivity meter if your unsure of what your giving
Keep in mind most disolved solids readings are usually on the low side, and
actual nutrient levels are usually higher. It is possible with passive
hydroponics, to get nutrient build-up over several feedings, to the point the
medium is over saturated in nutrients. Just feed straight water now and again,
until you notice the plants are not as green (slightly), then resume normal
"Pumping" is when you use more waterings to make the plants grow
faster. This is dangerous if you proceed in a reckless manner, due to potential
over-watering problems. You must go slowly and watch the plants daily and even
hourly at first to be sure your not over-watering the plants. Use weaker plant
food mixtures than normal, maybe 25%, and be sure your leaching once a month and
running straight water through the plants at least every other time you water.
This applies mainly to plants grown in soil mediums.
Use of light strength Oxygen Plus plant food (or Food Grade Hydrogen
Peroxide) allows the roots to breath better and prevents problems with
over-watering. Check soil to be sure there are no PH anomalies that might be due
to Hydrogen Peroxide in the solution. (One experienced grower told me he would
not use h1O2 (HP) due to possible PH problems. This should not be a problem if
your checking PH and correcting for it in watering solutions.)
Be sure your medium has good drainage. At this point, if your watering soil
based plants once a week, you can water every 3-5 days instead if you plant them
in a medium with better drainage. Pearlite or lava rock will greatly increase
the drainage of the medium and make watering necessary more often. This will
pump the plants; they will tend to grow faster because of the enhanced oxygen to
the roots. Make sure the plant medium is almost dry before watering again, as
the plant grows faster this way.
An alternative is to use a standard plant food mixture (stronger) once every
3 waterings. The nutrients are suspended in the medium and stored in the soil
for later use. The nutrients are washed out by 2 straight waterings afterward
and there is no salts build up in the soil. (Does not apply to hydroponics.)
Stop all plant food 2 weeks before harvesting, so that the plants don not
taste like plant food. (This applies to hydroponics as well.)
WARNING: Do not over-fertilize. It will kill your plants. Always read the
instructions for the fertilizer being used. Use 1/2 strength if adding to the
water for all feedings in soil or hydroponics if you are unsure of what your
plants can take. Build up slowly to higher concentrations of food over time.
Novice soil growers tend to over-fertilize their plants. Mineral salts build up
over time to higher levels of disolved solids. Use straight water for one
feeding in hydroponics if it is believed the buildup is getting too great. Leach
plants in pots every month. If your plants look REALLY green, withhold food for
a while to be sure they are not being over-fed.