If you properly fertilized in the Fall, there’s no need to apply another layer of fertilizer in the Spring. Cool season grasses, in particular, are good at grasping on to fertilizer from the fall and using it all winter. However, if you have warm season grass then applying a fresh layer of fertilizer during the spring would be good because they begin to soak up the nutrients as soon as the weather gets warmer.
So if you’re fertilizing during the spring then a slow-release nitrogen fertilizer is best. However, no more than a pound of nitrogen should be spread per 1,000 square feet. Fertilizer should not be applied too early or late because the lingering cold or early heat can stress the grass.