Dormant seeding of turfgrass
By David G. Hallauer
Meadowlark District Extension Agent
We're past the optimum seeding time for cool-season turfgrasses (that's September), but if you have some "filling in" to do, consider dormant overseeding. Dormant overseeding is done during the winter (December to February) when it is much too cold for germination.
To be successful, good seed-soil contact is vital and may be achieved using several methods. One is to seed when there has been a light snowfall of up to an inch. The snow will be shallow enough that you can still see bare spots so you know where to seed, and as the snow melts, it brings the seed into good contact with the soil where it will germinate in the spring.
You can also surface seed when moist with some freezing weather to follow. As moist soil freezes and thaws, small pockets are formed that is perfect for catching and holding seed. As the soil dries, the pockets collapse, covering the seed.
You can also broadcast seed immediately following core aerating, verticutting or hand raking. Soil must be dry enough and unfrozen for this to be practical.
Seed will germinate as soon in the fall as it can. Just don't forget herbicide limitations for the new seeding. Some of our traditional crabgrass and even broadleaf herbicides can inhibit germination. Most require turf to be well established prior to application. If you need a weed control option associated with a new seeding, contact your Extension agent.