When Do I Need to Fertilize?

Lawn Schedule

• Developing a schedule of fertilization for your lawn helps to strengthen the root system. Turf grass with a strong root system is less susceptible to stress from drought and heat in areas that experience hot summer months. In all areas of the country, a well-fertilized lawn means greener grass and better resistance to pests or diseases. At minimum, fertilize your lawn once a year during the fall before your grass goes dormant for the winter. This helps your grass store nitrogen that will produce healthier grass when new growth begins in the spring. A fertilization schedule of four times per year, however, is recommended for optimal turf health. Fertilize once during the early spring, just as new growth begins, again during the late spring months of April and May, a third time during the summer months and finally during the fall.

Shrubs and Trees

• Shrubs and trees also benefit from fertilizer applications during the fall or spring. But depending on your location, the type of plant you are growing and the proximity of your plant’s root system to your lawn, you may not have to fertilize your trees or shrubs every year. If the plant’s root system is close to a lawn that is receiving regular fertilizer applications, a separate application of fertilizer is too much. The best thing to do is observe your plants individually and see what they respond to best. Generally, do not fertilize newly planted trees or shrubs during the first year. Wait until the following spring so the plant has time to develop a root system and adjust to the environment. When fertilizing in the spring, apply a slow-release fertilizer in early spring, just before new growth emerges. For fall applications, fertilize trees and shrubs prior to the first frost. Never fertilize trees or shrubs during the late summer months, as this may stimulate new growth that is susceptible to frost damage later on.

Annuals and Perennials

• Annual and perennial flowers are best fertilized during the spring when you prepare your beds for planting. Choose a slow-release fertilizer and work the solution or granules into the top 6 inches of soil prior to planting your flowers. For established perennials that are scheduled to come up the following season, fertilize in the early spring, just as new growth is about to emerge. Work your fertilizer into the top layer of soil and water your plants thoroughly to work the fertilizer down to the plant’s root system. Always be sure to remove any mulch layers before adding fertilizer to the soil. A once-a-year fertilizer application is sufficient for healthy growth and bud production in annual and perennial flowers and ornamental grasses.

Precautions and Considerations

• Read the directions and go with the lightest application when fertilizing your lawn, plants and flowers for the first time. Too much fertilizer has a negative effect on your plants. Overfertilization also results in excessive or rapid growth, which makes plants susceptible to injury and stress. Fertilizer burn comes from applying too much fertilizer and can result in loss of vigor, defoliation and stress in plants. Plants and trees that are under stress are more susceptible to invasion by pests and diseases. Perform a soil test to ensure your fertilizer formula fits with the plants you're growing.