Foliar feeding is the process of adding fertilizer (nutrients) into a spray bottle and feeding the plants via the leaves rather than watering the medium to remove deficiencies. This allows for nutrients to pass directly into the plant’s vascular system via leaf and stem absorption. Foliar feeding is a great way to rid your plants of deficiencies and allows you to directly assist the area of the plant that is deficient.
It is not recommended that you use foliar feeding as an alternative to regular feeding in soil and coco because plants uptake major (macro) nutrients like Nitrogen, Phosphorus and Potassium (NPK) in large quantities and the best way for them to do this is via the root system as they are much larger and cannot be taken in through the leaves. You can however foliar feed smaller, micronutrients such as Iron and Zinc.
Foliar feeding works by absorbing nutrients through the epidermis or through the stomata once they have been sprayed lightly on leaves or stems. The stomata refers to small pores found on the underside of healthy leaves and the epidermis refers to the outer layer of cells on a plant. The stomata are kept healthy through correct grow room humidity.
- Corrective nutrition- A fast and effective way of tending to nutrient deficiency, as foliar uptake occurs faster than root uptake.
- Boosting growth- If you precisely time when to begin foliar feeding you can greatly improve your plant’s yield and growth! This can be done by applying nutrients during the critical stages of growth in which plants have lower concentrations of much needed nutrients.
- Efficiency- Helps to activate specific plant mechanisms, such as stimulating flowering
- Complementary Nutrition- In the event that your plant is stunted due to pests, stress or diseases, plants will benefit from added nutrients to support them as they come out of this.
If you are considering foliar feeding – great! Just remember that everything comes with negatives and with foliar feeding, some of those negatives can result in your plant dying if you are not cautious!
Overfeeding plants can happen easily with foliar feeding, its important to remember not to create a feed that is too strong as this can cause Phytotoxicity, turning your once fresh, green and healthy leaves into yellow, crispy and dry leaves.
Another concern is Nitrogen toxicity, in which leaves turn darker green and begin to become misshapen or distorted due to the plant trying to grow faster than it is able to.
Whenever you make a foliar feed for your plant make sure to test it on a couple of leaves to make sure that there is not too high a concentration of nutrients. If any of your leaves scorch and burn, dilute your feed more until this stops. It should be noted that you can only foliar feed If your lighting system is OFF! Drops of liquid on delicate plant leaves can often act as magnifiers for light, intensifying the light and burning the leaves! (think of burning ants with a magnifying glass!)
Finally, make sure you never over-saturate leaves with foliar feed and ensure to only spray a fine mist on both sides of the leaves to allow for a faster uptake.