Grass Seed Germination
The first stage in any seed's growth cycle is germination. Germination occurs in grass seeds when they are exposed to the correct combination of heat and moisture. Different varieties of grass seeds have varying germination times. For example, although many types of grass seeds can germinate in as soon as a week from planting, bluegrass seeds take up to a month. Ryegrass seeds germinate the fastest, and many commercial grass seed mixes combine different grasses so that you see results quickly. The mix permits grass to start growing in your lawn almost right away, and then thicken out as the later germinating varieties appear.
Grass Seed Growth
Once grass seeds have been sown and the soil is moist, the individual seeds start to send out roots and a stem. The stem eventually produces shoots and blades. The roots extend as the grass grows, not only helping anchor the plant into the soil, but also absorbing water and nutrients. Creeping grasses have roots that send out runners, or rhizomes, that become new plants. Some roots grow out of and then over the surface of the soil and are called stolons. If you sow grass seeds on a bare patch, it will take four to six weeks to become fully established. You can mow your lawn once the blades are at least 3 inches high.
Grass Seed For Your Region
Grass varieties are classified as warm or cool-season seeds. Grass seeds that are bred for cool-weather germinate in temperatures above 45 degrees. However, warm-season grasses will not germinate at such low temperatures. They need at least 55 degrees to start germinating. Although they tolerate dry and hot summers well, they need mild winters to survive. Warm-season grasses tend to have wide blades and are not as fine as the grasses found in cooler regions. Cool-weather grasses survive freezing winter temperatures, but unlike warm-season grass that grows in summer, cool-weather grass grows during the spring and fall and is dormant in summer.
If you live in a cool region, sow grass seed once high summer temperatures have abated in late summer or early fall. Keep the soil humid, but avoid over-watering. Too much water will drown the germinating seeds. A thin layer of mulch---less than 1/4 inch--helps retain water without allowing it to form puddles. On the other hand, if you live in a warmer region, plant grass seeds once overnight temperatures have reached the mid to high 50's. No matter where you live, once you sow grass seed, avoid walking on your lawn as much as possible for at least a month.