How to use Foliar Feeding with Cannabis
Foliar 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 premade cannabis foliar feed 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.
Timing of Foliar Feedings
The best times of day for Foliar feed are 7-10 am and after 5 pm 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 is hot, and the warmer part of the day if it is cold out. You may need to spray at 2 AM if that is 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 is 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 do not 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.