Jonathan Green Green-Up lawn food is a quick, deep greening fertilizer that can be used on all types of turf grass and will feed the lawn for up to three months. The polymer-coated nitrogen in this product provides a slow and steady food release, preventing a surge of grass growth in the early spring, which reduces grass clippings when mowing. Green-Up is the finest fertilizer to use in the early spring if crabgrass is not present.