Foliar feeding refers to spraying the leaves of your plants with a nutrient-rich tea, and is a simple way of aiding plant growth and increasing both the yield and quality of your harvest. It is best used when growing in a well-ventilated space, such as outdoors. Foliar feeding should be done throughout the vegetative growth stage, and into early flowering, but should be stopped two to three weeks before harvesting to avoid tainting your finished product.
Your foliar solution should be a combination of your plant food of preference and water, and have an optimal pH level between 6.2 and 7. If the pH is too high, add vinegar to increase acidity; if the the pH is too low, add baking soda to increase alkalinity. You may also choose to add soda water to your solution, which will introduce CO2.
Foliar feeding is best done in the early morning and evening, due to the cooler temperature and lack of direct sunlight. You want the temperature to be around 72 degrees, because the stomata of the plants will be open and able to absorb the solution. You must make sure to wash the leaves of the plants with water at least once a week to prevent these stomata from clogging. It is important to find a spray bottle that will produce a fine mist, as you do not want to drench the leaves of the plant. Ensure you never spray while the leaves of the plant are in the sun, as this can cause them to burn.
*If you choose to foliar feed, it is imperative that you wash the leaves of the plant thoroughly before they are harvested, to ensure you are not consuming plant food.