If your turf hasn’t greened up this fall like you may have liked, dormant seeding might be an option for you to consider. Dormant seeding is the next best timing after late summer seeding for establishing cool-season grasses.
What makes dormant seeding different from a late summer/early fall seeding is that you will be broadcasting the seed on nearly frozen soil. The soil temperatures, plus the air temperatures, will keep the seed you broadcast dormant until spring, hence the name, dormant seeding. On the other hand, late summer seeding needs to be done early enough for the seed to germinate and establish before going dormant for the winter. The optimum deadline to have that done is Sept. 15, although you can certainly gamble and push it back, in hopes we won’t get an early frost.
Back to dormant seeding — the best time to dormant seed is any time after soil temperatures are about 40 degrees in order to guarantee no germination until next spring. Seeding between Thanksgiving and St. Patricks’ Day is a good rule of thumb. You can broadcast the seed, and while simply broadcasting the seed and allowing it to work into the soil naturally through frost-heaving can be effective, it is better to improve seed-soil contact with aerification, tilling, or power-overseeding. Really any sort of cultivation will better help the seed come into contact with the soil. If your soil is wet or frozen, you might not have much choice, but maximizing seed-soil contact is essential for successful dormant-seeding.
Two of the best cool season grasses for dormant seeding are Kentucky bluegrass and tall fescue. Unfortunately, perennial ryegrass may germinate prematurely in a mid-winter warm-up only to die in ensuing cold temperatures. A warm season grass, Buffalograss, can also be dormant seeded.
Typical dormant seeding rate recommendations are to seed at 10-25 percent higher rates than normal. This helps account for seed loss from erosion, animal feeding, etc. Seed Kentucky bluegrass at 3.0 pounds/1000 square feet, tall fescue at 10 pounds/1000 square feet, and buffalograss at 3.5 pounds/1000 square feet on bare soils. If you are simply over-seeding in existing, but thin turf, these rates can be cut by as much as one half.
Starter fertilizer should be applied next spring as the seedlings emerge. Apply 1.0 to 1.50 pounds
Phosphorus/1000 square feet, depending on soil test levels. This same fertilizer and same rate should be applied again four to five weeks after emergence and maybe possibly again at eight to ten weeks after emergence depending on the density of the new stand.
Dormant-seeded areas will need irrigation just like any new seeding. Irrigate as needed to maintain moisture in the top one-quarter inch of soil, which will vary greatly depending on precipitation we receive.
Irrigate less regularly and in larger volumes as the seedlings establish. However, dormant-seeded areas might need irrigation all summer as these relatively young plants will not be mature enough to withstand drought stress.
Early mowing on any newly-seeded area encourages lateral spread and quick fill-in. On most areas, set the mower 10-20 percent lower than the regular mowing height for the first three to five mowings to encourage the most rapid fill-in. Dormant-seedlings will be emerging early next spring so most pre-herbicides cannot be used over dormant seeded areas. However, early weed control is critical to minimize weed competition and maximize establishment. In some cases where weed pressure is high, it is justified to apply herbicides.
Natalia Bjorklund is the horticulture educator in Dodge County. If you have plant or insect questions, drop by the office here in Fremont at 1206 W. 23rd St. or call at 402-727-02775. You can also email her your questions at firstname.lastname@example.org.