How Often Should You Apply Lawn Fertilizer?

One yearly application of fertilizer can be adequate for well-established lawns.

How often you fertilize your lawn depends on a number of factors: the shape of your lawn, the age of your lawn and, just as important, your personal opinions regarding fertilizers and the environment. Well-established lawns may need fertilizing only once a year or less. Newer lawns, or lawns undergoing renovation, may benefit from a more aggressive fertilization program.

Fertilizing Frequency

The University of Rhode Island Landscape Horticulture Program recommends three applications of fertilizer per year. Apply the first round in early spring. A second application around Labor Day will encourage fall growth. A third around Thanksgiving will stimulate root growth through the winter months and result in an early spring green-up. Mature lawns often do fine with only one application of fertilizer per year.

Types of Fertilizer

Most lawn fertilizers contain the same basic ingredients. Nitrogen helps the grass green-up and grow thick; potassium toughens the turf to resist drought, wear-and-tear, disease and cold; and phosphorous encourages strong root growth. This combination of ingredients is available in four forms of fertilizer: granular, liquid, synthetic and organic.

Granular fertilizers typically requires less frequent applications than either liquid or synthetic. It is easy to spread and comes in slow-release or fast-release formulas. Slow-release allows more time between applications. Fast-release works better in cold weather and costs less, but is prone to grass burn and requires consistent watering. Liquid fertilizers work immediately, but must be applied more frequently. Synthetic fertilizers penetrate the soil quickly, but create more risk for lawn burn and, like liquid, must be applied more often for consistent results. Organic lawn fertilizers can improve the texture and density of your lawn by improving the health of your soil. Like granular fertilizers, the organic type can be applied from one to three times per year, depending upon the health and needs of the lawn.

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Best Seasons to Fertilize

Always fertilize during the growing season. For warm-season grasses, such as Bermuda and zoysia, fertilize in the spring and summer months. Cool-season grasses, such as Kentucky blue grass, fescue and rye grass, benefit from early spring and fall applications. If you apply fertilizer only once per year, make it in the early spring for warm-season grasses and in the fall for cool-season varieties.

Ways to Reduce Fertilizing

One way to reduce fertilizing is to simply not bag your grass clippings. When clippings are allowed to remain on the lawn, they decompose and act as a natural, organic fertilizer. Consistently watering your lawn and mowing it at a height of 2 to 3 inches also creates a denser, healthier lawn that is resistant to weeds and insects --- and requires less fertilizing. A thick, healthy lawn requires far less fertilizer than one that is stressed or undergoing renovation.

References

• University of Rhode Island Landscape Horticulture Program: General Lawn Maintenance and Renovation
• Plant-Care.com: Lawn Care Tips
• Colorado State University Extension: Lawn Care
• Plant-Care.com: Lawn Fertilizer
• Connecticut Department of Environmental Protection: Don't Trash Grass
• Planet Natural: Organic Lawn Care