Fertilizing your lawn before the soil temperature is adequately warm results in waste of fertilizer and possible lawn injury. Certain fertilizer elements are not readily available under cool soil conditions and potentially leach below the root zone before the roots are in a position to take in the elements.
Despite the fact that you can easily force your lawn to turn green early with many of the high nitrogen fertilizers, it’s a false sense of accomplishment. That new green growth is dependent on the availability of other elements, some of which are poorly available under cool soil temperatures. Iron, for example, is not readily available while the soil is cool. This is exactly what happens when your lawns begins to turn bright yellow after being fertilized too early. In other words, you’ve induced or caused a nutrient deficiency by fertilizing too early. It’s simply a matter of the soil being too cool to allow the roots to take in the needed iron to support the new growth you’ve caused by fertilizing too soon.
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 grass roots are in a position to use them. 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 much 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 the local lake now. It takes consistently warm night temperatures in order for the water to warm. This is true with the soil as well.
In order for our warm season grasses, such as centipede and St. Augustine, to efficiently use fertilizer, consistently warmer nights are required. 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.