Fertilizing & Reseeding Grass

Fertilization Season

• Traditionally, gardeners apply fertilizer to lawns during the spring, but some modern sources recommend switching to late summer and fall fertilizer applications. Spring fertilizer applications work well because they provide the grass nutrients right as they begin a growth spurt due to the warming weather. However, late summer and fall applications may work even better because they keep lawns greener for longer during fall and prevent lawn diseases during the summer. Gardeners reseeding a lawn area in the spring should also apply some fertilizer during the spring.

Fertilizer Amount

• Although grass needs many nutrients to grow, it mostly requires nitrogen from its fertilizer. Therefore, gardening experts recommend fertilizers based on nitrogen amounts. To get information about whether a lawn may need additional nutrients, the University of Minnesota Extension recommends getting a soil test. Sun-loving grasses that grow quickly, such as Kentucky bluegrass and many turf grass seed mixtures, need 2 to 4 lbs. of nitrogen per 1000 square feet of grass per year. Lawns in shady areas and with low-maintenance grass types, like red fescue and hard fescue, require only 1 to 2 lbs. of nitrogen per 1000 square feet per year. The gardener should split the fertilizer up into at least a few separate applications, sprinkling a maximum of 1 lb. of fertilizer on top of the grass at a time.

Fertilizing Before Seeding

• At the time of seeding a new lawn or reseeding a bald patch, gardeners should mix in 1/2 lb. of nitrogen for every 1000 square feet of space, as the University of Minnesota Extension recommends. Applying fertilizer to a bare area differs from applying fertilizer to an existing lawn, because the gardener can mix the fertilizer into the top layer of soil with a rake or tiller.

Reseeding

• Before reseeding an area, rake it to remove dead grass. Mix in the 1/2 lb. of nitrogen recommended at times of seeding and also mix in 1 or 2 inches of peat moss or topsoil to compacted soils to make them more workable. Wait until after the last frost of the spring to reseed. Spread a grass seed mixture over the bald area according to the seeding rates specified by the manufacturer. Different types of grasses require different seeding densities. For example, gardeners should spread 15 to 30 lbs. of ryegrass seed per acre and 15 to 20 lbs. of fescue seed per acre. Rake the area to create ridges that prevent grass seed from blowing away. Keep the seeds consistently moist until they sprout.