What is foliar feeding (foliar spray)?

Foliar feeding is the process of spraying plants, trees or shrubs with a fine mist of liquid fertilizer (or other liquid amendment) from a sprayer. Plants have the ability to absorb nutrients more quickly through their leaves and vascular system than through their roots in the soil. Pesticides may also be applied through a foliar spray.

One common example where foliar feeding may be necessary is addressing blossom end rot in tomatoes, which is caused by a calcium deficiency in the plant.