When to fertilize lawn depends on the kind of grass that you grow. The grasses require nitrogen and other nutrients during the seasons of active growth. You have to space your applications far away because your grass will grow fine for a while and then slows down and after that it is perfect for you to speed up again with the next application.
When should I fertilize my lawn?
A couple of warm-season grasses such as St. Augustine and Bermuda grass grow quickly in warm weather. When to fertilize lawn in spring depends on the nitrogen which promotes quick growth of cool-season weeds. It is better not to do that. If you fertilize your lawn too late in fall season, the grass is less hardy because it enters cold weather and more susceptible to winter injury.
Cool-season grasses like tall fescue and Kentucky bluegrass grow rapidly in the cooler months of spring and fall. In mild-winter climates like the Deep South and Southern California, cool-season grasses can grow via winter. So the most perfect time to feed cool-season grasses is in spring and fall and often in winter. Specifically, fall is a very crucial time in order to feed cool-season grasses which is keeping them growing longer into cool weather and offering the reserves required for quick green-up in spring time. You will end up with overly lush top growth at the expense of root growth and you can get some problem. Besides that, if you fertilize your lawn in fall, the lawn does not require another application until later in the spring.
It is better for you to avoid fertilizing during the heat of midsummer, even though cool-season grasses stay green. Applying fertilizer at very hot weather can actually weaken the law while growth naturally slows down in that time. The only exception is those lawns which are growing in far northern or high-elevation climates where the weather stays cool relatively all summer. Lawns can be fed in those areas throughout the growing season.
In order to get maximum appearance, you have to fertilize your lawn about once every six up to eight weeks during their active-growth time. You can simply break up the yearly requirement of nitrogen into a couple of important applications, let say one or two in spring time and two or three in fall time for cool-season grasses, and three in summer time for warm-season grasses.