Chemical Plant Fertilizers 101
Of all the topics surrounding growing plants in general feeding seems to be one of the most misunderstood of them all. Read one article that's supposedly written by an experienced expert and it will tell you one thing. Then read another written by yet one more experienced grower and in it he or she will be telling you something completely different.
So too often for first-time growers and even for those who have done it for a while, plant nutrients and how they are applied ends up being a process of experimentation. The problem here though, is that learning on your own by “trial and error” while effective in the long run is an expensive process, with the operative word here being “error”.
Every type of chemical plant fertilizer you can buy at your local nursery will come with instructions on the container, even if they are generalized. That is that they've been worded to accommodate all growers of all types of plants. Even so, even with generalized instructions you will get some type of basic parameter to operate within.
What you need to know up front about cannabis is that it grows optimally in pH balanced soil. Roughly between pH 6.5 and 7. Go above that number and the roots become susceptible to infection. Go below that number and the soil becomes more acidic, and acid soil will burn the fine hairs off the roots.
So if you use a chemical fertilizer, like perhaps Rapid Gro or Miracle Grow, it will come with a plastic scoop in the package. Read the instructions and almost without exception they're going to instruct you to add one scoop per gallon of water. So follow the instructions and add one scoop per gallon of water but keep something in mind here. That is that smaller plants need far less of the solution than larger plants.
So if you're, say fertilizing starts in cups you'll want to give each one about 4 ounces of this solution every two weeks. Then as they grow and you then transplant them into larger containers or into the ground, increase the amount accordingly with a 3 foot plant getting about a gallon of solution every two weeks and a 6 to 8 foot tall plant getting about 5 gallons every two to three weeks.
A big mistake too many novice growers make is thinking that they can 'force a plant to do something' by overdoing it with chemical fertilizer. That they can force it to grow by adding extra fertilizer or force it to flower by adding Bloom 0 -10 -10 early in the season. The only thing that over-fertilizing will force a plant to do, is it will force to stop growing at a normal rate.
Yes it will start throwing out flower hairs early but that's only a natural survival mechanism. The plant senses it's under attack and its life is in danger, so it's natural response is to throw out some flowers in the hopes that it produces some seeds before it's killed. All you're going to get though, is skimpy hairs with little resin instead of full buds.
Foliar feeding is a great way to ramp up your plants nutrient intake without any risk to the roots. Do be aware however, that foliar feeding on its own is not a silver bullet to enhanced growth. If you foliar feed you'll also need adequate light, room and ventilation because just like any other living organism it takes more than just food for healthy growth. Too much food under the wrong conditions will lead to health issues.
So triple triple your chemical fertilizer blend. That is that when the instructions say to add one scoop per gallon, add three scoops per gallon then let it dissolve. Next add about six or seven drops of liquid dish soap to the mix to function as a wedding agent and a teaspoon of Epsom salts for magnesium. If you don't add the dish soap the solution is just going to bead-up and roll off the leaves.
Simply spray this concentrated solution right on your plants but make sure that you do it when it's not getting hit by direct sunlight or when your lights are on. The reason here is that the beads of water will function like little magnifying glasses and cause burned spots on the leaves. Also the warmer it is the quicker the solution will dry out on the plant and you want it to stay wet so it soaks in well.
Then your last bit of advice here is to keep close track and even keep a written record of how much and how often you're fertilizing your plants. Use a measuring cup or container to pour the liquid too because the last thing you want to do is just 'eyeball it' while you pour on fertilizer solution because you'll end up with some getting too much and others getting too little.
If you do end up in a situation somewhere along the line where you've somehow overdone it it with your fertilizer, hydrated lime works great for neutralizing acid. Add about 3 tablespoons per gallon of water, let it dissolve through and then pour it on the plant soil you feel you've over fertilized. Then follow up by washing it through with plain clear water.
Fertilizers can make you or break you. They can give you 12 foot trees if you use them right or 6 inch tall sickly, spindly shrubs if you use them incorrectly. So it's best to ere on the side of caution if you're in doubt. Then finally if you've been smoking or drinking wait until you have a clear head before you start in fertilizing your plants because even small mistakes can be costly.