Grass seed germination is dependent on soil temperatures, planting site preparation, fertile soil and moisture. For example, grass seed thrown on the soil during the heat of the summer has little chance to germinate. Cool-season and warm-season grasses have different needs when it comes to germination. Gardeners must determine the best time for sowing their chosen grass type.
Cool and Warm Season Grass Types
Cool-season grass types such as ryegrasses, fescues and bluegrasses have a shorter germination time when sowed in the late summer to early fall, according to Iowa State University. While gardeners may be tempted to plant this grass type in the early spring, they stand a chance of losing their lawn to the heat of the summer before it has time to establish. Warm-season grass types like Bermuda, bahia, buffalo, centipede and zoysia grasses are sowed in the late spring when soil temperatures have warmed up to 18.3 to 23.9 degrees Celsius, according to Virginia Cooperative Extension.
All weeds and other vegetation must be removed from the planting site. Weeds compete with new seedlings for the soil's nutrients. To get rid of weeds, spray the lawn with a herbicide that contains glyphosate, as suggested by the University of Minnesota. Work a starter fertiliser into the first 2 to 4 inches of topsoil, as recommended by the University of California. Starter fertilisers have a high percentage of phosphorous, which benefits root development.
Sow your grass seeds according to their recommended distribution rate. Broadcasting too few leaves bare areas, and spreading too many grass seeds slows their establishment time, according to the University of Minnesota. For example, Bermuda grass seed should be distributed at a rate of 0.454kg. per 1,000 square feet. Kentucky bluegrass is broadcast at a rate of 2 to 3lbs. per 1,000 square feet. Cover your grass seeds with 1/8 inch of dirt or compost to help conserve soil moisture.
All grass types germinate at different rates. For instance, buffalo grass takes 14 to 30 days to germinate, tall fescue takes seven to 12 days, Kentucky bluegrass takes 14 to 30, Bermuda takes 10 to 30 and annual ryegrass takes five to 10, according to the University of California. For grass seed to germinate properly, gardeners must keep the soil moist until seedlings emerge. This may mean that you apply water to the lawn two to three times a day.
- Iowa State University Extension; Seeding a New Lawn; Richard Jauron
- University of Minnesota Extension; Lawn Renovation; R.J. Mugaas and B.W. Pedersen
- University of California Agriculture and Natural Resources; Grass Seed Germination Rates
- Virginia Cooperative Extension; Spring and Summer Lawn Management Considerations for Warm-Season Turfgrasses; Mike Groatley