Late Fall Turf Seeding
Posted: October 9, 2012
The reason that mid-fall can be risky for seeding is that killing cold temperatures may arrive before the newly germinated plants have a chance to gain the critical maturity level needed to survive the winter. Both Kentucky bluegrass and tall fescue take a long time to germinate even when soil temperatures and conditions are ideal. As soils cool later in fall, germination can take even longer. Young seedlings are very prone to low temperature kill until the four-leaf stage is reached. The physiological changes that prepare the plant for cold tolerance take time to develop. Also, grass species vary in their cold tolerance. If new seedings are made when the soil is still warm enough for germination but there’s not enough time for them to get established, they can succumb to winterkill.
So there is a period from mid October through mid-November that can be risky for new seedings. To reduce that risk, plant sod instead of seed; or wait a month and plant after the likelihood of germination is past (when soil temperatures go below 40 degrees), a process called dormant seeding.
Dormant seeding is done anytime from November through March when air and soil temperatures are too low for germination. It’s a practice done all the time on most athletic fields when the playing season ends around Thanksgiving. There are benefits: soil preparation and seeding can be done any time when the soil is dry enough to work; the seed will be in place, ready to germinate as soon as soil temperatures warm next spring; soil heaving and cracking during the winter can improve seed-soil contact; moisture levels tend to be suitable; and turf cover is greater the following summer when compared to traditional spring seeding.
In research trials, the advantages of dormant seeding vary depending on the turf species. But if either tall fescue or Kentucky bluegrass is the main species being planted, consider dormant seeding over spring seeding. Both of these grasses had less winter kill and more turf cover the following summer when dormant seeded.
Kentucky bluegrass establishment was most positively impacted when dormant seeded as opposed to spring seeded. The results for tall fescue and perennial ryegrass were not as pronounced, however earlier turf coverage resulted from dormant seeding over spring seeding. Research supports dormant seeding over spring seeding especially in areas where regular irrigation is not available through the late spring and into summer.
Additional pointers that can increase the success of dormant seeding include using mulches or turf blankets whenever seeding is done; increasing the seeding rate about 30% to account for losses; and keeping an eye out for weed competition in the newly seeded areas next spring.