Can You Use Liquid Fertilizer on Plant Leaves & Granular Fertilizer in Potting Soil?

Fertilizer on Plant Leaves

• Adding fertilizer to the leaves is, almost without exception, a bad idea. Plants do not take in nutrients from their leaves. Instead, they breathe and photosynthesize with their leaves. Other than oxygen and carbon dioxide, leaves do not absorb any nutrients, so adding fertilizer to leaves, whether liquid or granular form, will have no positive effect on the leaves. Instead, it likely will burn up the plant up or inhibit the leaves' ability to photosynthesize.

Liquid Fertilizer

• Liquid fertilizer is intended for use in the soil. Fertilizer in liquid form provides a benefit: Nutrients will make their way deep into the soil, getting to the plant's root system quickly. This way, plants that are especially deficient in nitrogen or other nutrients can receive the nutrition they need before it's too late.

Granular Fertilizer

• Granular fertilizers are distributed around a plant in need or spread over an entire yard if the yard is especially nutrient-deficient. Granular fertilizers release much more slowly than liquid fertilizers, gradually finding their way into the soil and toward the root system as rain disintegrates the granules. This is generally more efficient as an inorganic fertilizer than liquid fertilizer, as plants and soil are not overloaded with more nutrients than are necessary, and unnecessary nutrients aren't washed away before the plant uses them.

Exception to the Rule

• Compost tea is one "fertilizer" gardeners can apply to a plant's leaves. Compost tea is actually more of an inoculation than a fertilizer, providing the soil with millions of microorganisms that help ease the transfer of nutrients from the soil to plants. When added to plant leaves, the beneficial microorganisms in compost tea crowd the leaf and kill or kick out any parasitic microorganisms or disease that may be present.