Master Gardeners of Northern Virginia

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Phlox Subulata (moss pink) in landscape. Photo © Elaine Mills

Garden Myth Busters! Landscape and Lawn

By Rachel Vecchio and Joyce Hylton, Extension Master Gardeners

lawn closeup

THE MYTH: Always fertilize your lawn in the spring.

THE REALITY: A homeowner’s lawn and garden spring to-do list is usually long, including getting out the fertilizer and putting the spreader to work. But that particular chore may not be as necessary as one might think. This decision will be based on two things: your expectations for the lawn AND the amount and timing of fall fertilization.

Bucket with spade and soil dug up for soil test
Soil Sampling

Proper fertilization (timing and amount) helps maintain the health and vigor of a lawn. Therefore, it is recommended that the homeowner do a soil test once every two or three years. While the soil test will indicate the presence of many elements such as calcium, magnesium, phosphorus, and potassium, its greatest value is the assessment of the soil’s pH. This number indicates the soil’s acidity or alkalinity and, consequently, its ability to support a specific crop. Turfgrasses perform best in a pH range of 6.2 to 6.5. A pH in this range allows the turfgrass to easily absorb the needed elements found in the soil. Therefore, based on the pH, the report may recommend the application of sufficient lime to move the pH into a desirable range. (Never apply lime without this recommendation; too much lime can have a negative effect.). Interestingly, the soil test will NOT evaluate nitrogen needs since it moves quickly through the soil. Instead, the report will refer you to a Soil Test Note # for further information about fertilizer use specific to your turfgrass. Soil test kits are available at local Virginia extension offices and Master Gardener plant clinics.

Once a lawn’s needed amendments are known, the question becomes when to apply the fertilizer. Current research indicates that autumn is the best time to fertilize cool season turfgrasses, such as Kentucky bluegrass, tall fescue, perennial rye grass, and fine fescue. Warm season turfgrasses, such as zoysia grass and Bermuda grass, may be fertilized in very late spring (May or June). In fact, fertilizing the lawn at the wrong time may do more harm than good. Research shows that cool season turfgrasses respond best to two or three applications of fertilizer in the fall, at least one month apart.  Additionally, a fourth feeding in late May at half rate is possible but not necessary. However, please keep in mind that a homeowner should NEVER apply more than a total of 3.5 pounds of nitrogen per 1000 square feet in a 12-month period. Please note the two Maintenance Calendars sites listed below which provide a simple guide to the timing of needed amendments.

SOURCES/REFERENCES:

Virginia Tech has a number of valuable publications that provide good guidance on the proper care of a lawn. Check out these sites:

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