Foliar Feeding

Marijuana Horticulture

by Jorge Cervantes

Foliar feeding means to spray the nutrients or bio-stimulants onto the foliage to augment available nutrients, vitamins, hormones, etc. Timing is key to achieving the best coverage and absorption.

The waxy (cuticle) surface coating (cystolith hairs and resin) on cannabis foliage makes them very poor water absorbers. This barrier wards off pest and disease attacks, but it also slows the penetration of sprays.

Young leaves are more permeable than older leaves. Nutrients and additives penetrate immature leaves faster than tougher, older leaves, and they are easier to damage with strong sprays.

Foliar feed the cannabis plants only when specific deficiency symptoms manifest. Foliar feeding is a quick fix only and is easy to overdo. High levels of nutrients in the foliage stop the roots from taking in more; this is confusing to the plant. Foliar sprays can accumulate and build up in the foliage. Never spray more than once every 10 days, and keep the spray concentration to less than 500 ppm or with an EC of less than 1.0.