It may seem like spring is the best time for planting grass seed, and you can do it, but you need to keep a few things in mind before you spend the time and money to do so. First of all, you need to consider the temperature that the soil has to reach before the seed will germinate. Bluegrass and Fine Fescue begin germinating when soil temperatures reach around 60 degrees. Perennial Ryegrass germinates when soil temperatures reach about 70 degrees. This means that you should wait until about May before you begin seeing any germination occur. How much grass seed do I need? Use this chart to determine how much seed you will need to apply per 1,000 sq. ft.:
The second consideration involves controlling weeds. If you seed in the spring, you cannot apply conventional crabgrass control products. These products will prevent crabgrass seed from germinating and it will keep your new seed from germinating as well. If the area that you are seeding has broadleaf weeds, such as dandelions or clover, you may not be able to use regular broadleaf weed controls. Most of those products state that you have to wait 6 to 8 weeks after the application before seeding. They also require the product cannot be applied until the lawn has been mowed 2 or 3 times after the seed has germinated. What this may mean is that your new grass will have to compete with weeds for the majority of the summer.
Another consideration is the length of time it takes for the seed to germinate. Ryegrass germinates in 5 to 7 days; Fine Fescue germinates in 7 to 10 days; and Bluegrass takes 28 days to germinate. The seed has to stay moist for the entire time from when it is sowed until it germinates. It also needs to receive water for at least two weeks after it germinates. If it is hot and dry, it will continue to need water until it is established.
Finally, you need to have good seed to soil contact to promote germination. Planting grass seed across an established lawn will result in very little germination. The best way to ensure good germination is to core aerate the lawn first and then broadcast the seed.
Planting grass seed in small areas in the spring may work, but trying to reseed your entire lawn in the spring is not a good idea. It is better to wait until mid to late August to seed. Soil temperatures are higher, rain is often more regular and weed pressure is less in the fall. Follow a good fertilization program and control weeds through the summer and the results will be better when you seed cool season grasses in the fall.