The best time to fertilize lawns is early to mid-April. Most people try to fertilize their lawns too early in the spring. It is important to wait for the right time to fertilize lawns. By now the warm season grasses common to our lawns, such as centipede, St. Augustine, bermuda and zoysia, have started their active growth, re-established a strong root system and are now ready for the extra nutrients fertilization provides.
Quite often fertilizing your lawn is optional. If your lawn has been largely healthy and attractive over the last few years with only occasional fertilization, you can choose to not fertilize. Fertilization will only make your grass grow faster and taller, resulting in your having to cut your grass twice as often. Lawns that definitely need fertilization are those that have sustained damage over the past few years. These are the lawns with missing spots that need to be filled in, thin spots that need to be thickened, and those whose owners desire perfection.
Adequate soil fertility also helps turf grass compete effectively with weeds. Well fertilized lawns usually have fewer weed problems than those that lack proper fertility. One example of this is clover infestation. Lawns with heavy clover populations in the winter and spring usually are deficient in soil nitrogen. Adequate nitrogen fertilization in the warm season is an effective way to reduce clover infestations the following winter.Since our lawns begin to green up in March, many gardeners wonder why we should wait until April to fertilize. Research shows that when certain types of grass such as St. Augustine, centipede, and bermuda first starts to turn green, it goes through a spring root decline. This is when much of the old root system dies, and the grass starts to produce new roots. This means turf grasses do not have extensive root systems during March, despite the grass blades beginning to grow. Applying fertilizer during March can stimulate the grass to put efforts into early leaf growth when it should be using it for roots. Early fertilization can cause the grass to go into the summer with a less-developed root system. Also with an inadequate root system, the grass will not be able to pick up the fertilizer.
When choosing a fertilizer the selection can be overwhelming. Remember there is not one fertilizer that is best. Just about any commercial lawn fertilizer will do a good job on your lawn. Be sure to check the label to be sure that one-third to one-half the nitrogen is designed to slowly release for extended feeding. A fertilizer with a ratio of 3:1:2 would work fine. The ratio of a fertilizer’s analysis – the three numbers on a fertilizer package that tell you the percentages of nitrogen, phosphorus (phosphate), and potassium (potash), respectively – is found by dividing each number in the analysis by the smallest number of the analysis. Fertilizers with a 3:1:2 ratio, such as 15-5-10, are also suitable for use on trees, shrubs, and flowers, as well as your lawn. This will simplify your fertilizer purchases. Fertilizers with similar analyses, such as 16-4-8, 12-4-8, or 19-5-9 would also be suitable. Most fertilizers that are specifically formulated for use on lawns, such as 18-0-18, or high nitrogen fertilizers, such as 27-3-3, will have good results on turf grass, but are not suitable for general landscape use.
It is recommended to apply fertilizer to your yard soon after it has been mowed. The shorter blades make it easier for the fertilizer granules to make soil contact. It is important to spread the fertilizer evenly and at the rate specified on the bag. Over-application can damage or burn the grass. The best way to distribute the fertilizer is to use a spreader or a fertilizer applicator. Apply half the needed fertilizer in one direction (east-west), then apply the other half in the opposite direction (north-south). Spreading fertilizer by hand often results in burned spots and uneven growth. Apply the fertilizer to dry turf and water it in thoroughly afterward.
Keep in mind, fertilizing turf grass is something we do to increase the quality of our lawns and is not a matter of life and death. For gardeners who strive for more, you can fertilize again in June and make a final application in August. However, in most cases one additional application in July will be sufficient. Generally, avoid fertilizing St. Augustine lawns after August. Nitrogen fertilization in the fall will increase the probability of brown patch disease in St. Augustine grass.