Time of Day for Fertilizing Plants

Fungal Diseases and Wet Foliage

• It is important to water early enough in the morning so leaves have time to dry out before cooler temperatures overnight, according to the University of Illinois. Cool night-time temperatures added to wet foliage caused by fertilizing encourages fungal diseases such as powdery mildew. The longer leaves stay wet, the higher the risk of fungal disease. When leaves dry out in the sun during the day, fungal spores cannot penetrate the foliage, notes Colorado State University.

Hot Afternoons

• Nitrogen burn is another reason to avoid afternoon fertilizing. The salts that make up nitrogen have the ability to dehydrate the plant when evaporation occurs in the afternoon. Furthermore, gardeners burn their plants with nitrogen when fertilizer is applied in hot weather, plants are water stressed or too much nitrogen is applied. Fertilizing landscape plants and grass while the soil is moist in the morning results in a lower risk of nitrogen burn.

Granule Fertilizer

• Typically, most lawns need 1 1/2 inches of water applied in the early morning each week, according to the University of Illinois. Landscape plants and vegetable plants need 1 inch of water per week. When applying a granule fertilizer in the early morning, supply 1 inch of water after fertilizing. Granule fertilizer may be applied with a rotary spreader when broadcasted through the yard or by hand when supplied around plants. Always use the exact amount indicated on the label to prevent nitrogen burn.

Liquid Fertilizer

• Gardeners dilute liquid fertilizer and apply it in the early morning to landscape plants both in the ground or growing in pots. Generally, liquid fertilizers for lawns are quick-release nitrogen fertilizers. This fertilizer type differs from slow-release fertilizers because they must be applied more often. Fertilizer injections are another form of liquid fertilizer used to feed trees and plants. Gardeners apply this fertilizer type on the dripline so the tree or plant root systems receive the nutrients.