Starting a new lawn or overseeding an existing lawn successfully is a process. When a newly seeded lawn fails to germinate or germination is uneven, a number of possible causes must be considered:
Selection of uncertified seed
Choosing state certified seed ensures quality seed that is packaged for the current year, with a good germination rate, use of recommended varieties and a low percentage of weed seeds
Lack of proper soil preparation
Fertilizer and lime should be applied, according to soil test results, prior to seeding. Soil should be raked or rototilled to provide an adequate seedbed.
Sowing seed at the wrong time of year
Mid-August through October is the best time to seed. Mid-February through March is the second best time for planting grass seed in Maryland. At these times there will a better chance of natural rainfall, optimum temperatures (40 -70 °F) and less weed competition.
Improper planting depth
Seed should be raked in, to ensure good soil contact, yet it should not be completely covered because it needs light to germinate.
Improper irrigation after planting
One of the most critical factors for successful establishment of new turfgrass seedlings is maintaining adequate soil moisture until the turf is well established. Without moisture, germination and early seedling survival will be poor and may result in complete failure of the stand. The root system of young seedlings is shallow and not extensively developed. Thus, maintaining moisture in the upper inch of the soil is especially important when seedlings are most sensitive to drying out, just after new shoots and roots have emerged. The average length of time for germination is 5-10 days for tall fescue and 14-21 days for bluegrass.