Expert Gardener All-Purpose Plant Food Fertilizer, contains a controlled release fertilizer that feeds your plants for up to 3 months. In addition to customized macronutrient levels of Nitrogen, Phosphorous, and Potassium targeting specific plants, Expert Gardener granular plant foods and fertilizers also contain a customized mix of micronutrients such as Iron, Manganese and Zinc. Micronutrients are essential elements every plant needs but are used by the plants in smaller amounts than the NPK macronutrients. Expert Gardener All-Purpose Plant Food is great for use on all flowers, roses, vegetables, fruits, ground covers, trees and shrubs.