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Wait to fertilize lawn: Many people fertilize their North Florida lawns too early

Larry Williams  Published 6:01 a.m. ET Mar. 19, 2021

Many people fertilize their North Florida lawns too early. Potentially, this results in lawn problems, waste of fertilizer and money. It is best to wait until your lawn is completely green before fertilizing, even if that’s not until April. Attempting to “jump start” a lawn by fertilizing before spring green up can result in numerous lawn problems, including injury from a late frost or freeze.

Our lawns begin to green and resume growth as a result of the longer day length and warmer temperatures of spring. Warmer night temperatures are particularly important. Fertilizing before the soil temperature is adequately warm results in waste of fertilizer and possible lawn injury.

Some fertilizer elements are not readily available under cool soil conditions and quickly leach below the root zone before the roots are in a position to take in these elements. Iron, for example, is not readily available while the soil is still cool. This is exactly what happens when a lawn begins to turn bright yellow after being fertilized too early. This is caused by fertilizing too early, while soil temperatures remain cool.

In most cases, it’s not that iron is deficient in the soil. Rather, it’s simply a matter of the soil being too cool to allow the roots to take in the needed iron. Iron is better available when the soil warms in spring, after the lawn naturally greens up and resumes growth.

There are other needed nutrients, such as potassium, which are not readily available under cool soil temperatures. As a result, some of these fertilizer elements leach below the root area before the grass roots are in a position to use them. In other words, as a result of fertilizing too early, you’re wasting fertilizer and money that’s washing away and not being used by your lawn. Waiting to fertilize during more favorable soil temperatures allows for more efficient use of the fertilizer and less waste.

The soil is somewhat like a body of water. Despite the fact that we’ve had a number of warmer days, the temperature of a pond or lake is still cold. You’d quickly realize this if you decided to go for a swim in a local lake now. It takes consistently warm night temperatures in order for the water to warm. This is true with the soil, too. In order for our warm season grasses, such centipede and St. Augustine, to efficiently use fertilizer, consistently warmer nights are required. The best indication that this has happened is when your lawn is completely green.

So why not wait until mid-April to fertilize? You’ll waste less fertilizer, save money and have a healthier lawn in the process. It’s a win, win, win situation.

Larry Williams is a UF/IFAS Extension Agent in Okaloosa County.