There are lots of ready made nutrients on the market some aimed at cannabis some not. In the end there's not much difference between any of them. As long as the nutrients are complete and given in the correct dosage results should be good.
Cannabis is a nitrogen lover and whilst in its growing stage it will need a feed with extra nitrogen. When flowering starts it will require extra phosphorus and potassium instead. This is why a lot of cannabis nutrients come in two or even three part formulas.
If a plant looks under fed check the p.h. of the medium and water before adding more nutrients. If your growing in soil make sure your not over watering and suffocating the plants roots. Soil should be allowed to dry a little between watering.
To easily control the rate and amount of food a plant receives use bland nutrient free mediums, with or without standard potting compost mixed in. Then add a soluble complete feed to the plants water in the recommended amounts.
Nutrients have an N.P.K. ratio on the packet. This shows the amount of Nitrogen(N), Phosphorus(P) and Potassium(K) the nutrient contains as a percentage. A complete fertiliser will also contain all the other nutrients and minerals a plant needs for good growth.
Mixing organic nutrients takes time and knowledge. Getting a good safe balanced mix for plants grown in the ground can take months. Start planning now if you want to grow organic and remember that you may still need to feed with a nutrient solution as well.
Whatever nutrient you use you should always stop feeding at least 10 days before harvest. Only give the plant p.h. balanced water from then on. Doing this will help "flush" the nutrients out the plant and produce better tasting and better burning buds.
PLANT FOOD AND NUTRIENTS
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 your plants.
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 feeding.
"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 H2O2 (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't 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.
PH AND FERTILIZERS
PH can make or break your nutrient solution. 6.7-6.2 is best to ensure there is no nutrient lock-up occurring. Hydroponics requires the solution to be PH corrected for the medium before exposing to the plants. Phosphoresic acid can make the PH go down; lime or potash can take it up when it gets too acid. Buy a PH meter for $10 and use it in soil, water, and hydroponic medium to make sure your not going alkaline or acid over time. Most neutral mediums can use a little vinegar to make them just this side of 7 ph to 6.5 or so.
Most fertilizers cause a ph change in the soil. Adding fertilizer to the soil almost always results in a more acidic ph.
As time goes on, the amount of salts produced by the breakdown of fertilizers in the soil causes the soil to become increasingly acidic and eventually the concentration of these salts in the soil will stunt the plant and cause browning out of the foliage. Also, as the plant gets older its roots become less effective in bringing food to the leaves. To avoid the accumulation of these salts in your soil and to ensure that your plant is getting all of the food it needs you can begin leaf feeding your plant at the age of about 1.5 months. Dissolve the fertilizer in worm water and spray the mixture directly onto the foliage. The leaves absorb the fertilizer into their veins. If you want to continue to put fertilizer into the soil as well as leaf feeding, be sure not to overdose your plants.
FOLAIR FEEDING
Folair feeding seems to be one of the easiest ways of increasing yield, growth speed, and quality in a well vented space, with or without elevated CO2 levels. Just prepare a tea of worm castings, fish emulsion, bat guano, or most any other plant food right for the job and feed in vegetative and early flowering stages. It is not recommended for late flowering, or you will be eating the sprayed-on material later. Stop foliar feeding 2-3 weeks before harvesting. Wash off the leaves with straight water every week to prevent clogging the stomata of the leaves. Feed daily or every other day.
Best times of day to Foliar feed are 7-10Am and after 5 in the evening. This is because the stomata on the underside of the leaves are open then. Also, the best temperature is about 72 degrees, and over 80, they may not be open at all. So find the cooler part of the day if it's hot, and the warmer part of the day if it's cold out. You may need to spray at 2AM if that's the coolest time available. The sprayer used should atomize the solution to a very fine mist; find your best sprayer and use it for this. Make sure the PH is between 7 and 6.2. Use baking soda to make the solution higher PH, and vinegar to make the solution lower PH. It's better to spray more often and use less, than to drench the plants infrequently. Use a wetting agent to prevent the water from beading up, and thereby burning the leaves as they act as small prisms.Make sure you don't spray a hot bulb; better yet, spray only when the bulb has cooled.
Perhaps the best foliar feeding includes using seltzer water and plant food at the same time. This way, CO2 and nutrients are feed directly to the leaves in the same spray.
Foliar feeding is recognized in most of the literature as being a good way to get nutrients to the plant later when nutrient lockup problems could start to reduce intake from the roots.
WARNING!: It is important to wash leaves that are harvested before they are dried, if you intend to eat them, since they may have nitrate salts on them.
NOTE: One grower who reviewed this document comments: "Fish emulsion smells. Bat guano could be highly unsanitary. Stick to the Rapid-Gro, MgSO4 (epsom salts), hydroponic trace element solution. Nitrate salts (The "N" in NPK) are unhealthy to smoke. Personally, I never foliar feed."
Above is a great comment, and there is great wisdom in an organic, non-toxic garden. Personally, I use only CO2 on my indoor hydroponic plants, and never folar feed. It simply does not seem to be necessary when using hydroponics.
Nice thread akina.............i just read the entire thread.