Traditionally, we think of seeding lawns in either spring (April-May) or fall (August-September), but there is another option - dormant seeding. With this method, the area is prepared in fall but the seed is not distributed until after the growing season has ended. Seed remains in place during winter, but does not begin to grow until soil temperatures are warm enough next spring for germination. So, if fall chores got away from you but your lawn still needs some work, consider dormant seeding.
Dormant seeding has several benefits. First, soil preparation can be done at your leisure during dry fall conditions. There’s no rush to get the work done in a short window of time in spring between frozen soil and wet soil. Dormant seeded turf grows well and fills in during cool spring weather, preventing much of the potential invasion by weeds. Finally, plants have more time to develop vigor and a good root system before hot summer conditions arrive, making them more able to tolerate summer stresses.
Soil Preparation Creates a Good Seedbed
The actual process of seedbed preparation is the same as at other times of the year, but dormant seeding is most effective when soil preparation - usually core aeration - is done in fall. Simply broadcasting seed and allowing it to work into the soil naturally through frost-heaving won't provide great success. Soil preparation to improve seed-soil contact is highly recommended and will be worth the effort.
Prepare small areas by hand raking to remove excess dead top growth and loosen the soil surface. The best technique for preparing larger areas is aerating. Aeration opens up the soil and provides a good surface for seed germination. Seeds that fall into the aeration holes will germinate and grow well; there is no need to topdress or fill in the holes before seeding.
Power raking can also be used to prepare the site, but is more damaging to existing turf and is not recommended when the existing turf is dormant and no longer growing. When plants are not growing, they have limited ability to repair power raking damage, so could be susceptible to winter injury. The only benefit of power raking over aeration is to reduce excess thatch. Up to ½” thatch is beneficial to lawns, acting as a mulch for turfgrass roots and cushioning the surface for more comfortable walking. However, if more than 1/2" thatch is present and power raking is used, go over the turf lightly only deep enough to penetrate the top ¼” of soil.
Once seedbed preparation is done, dormant seeding should ideally take place from mid-December through mid-February. Soil temperatures must be 40° degrees F or below to ensure seeds will not germinate. Since the seed needs to have good soil contact, don’t apply seed over snow. Dormant seeding should be done no later than March 15th.
The seeding rate for new, bare lawn areas is as follows: Kentucky bluegrass 2-3 lbs. per 1,000 sq.ft. and tall fescue 6-8 lbs. per 1,000 sq.ft.
The amount of seed applied when overseeding into a thin lawn is usually half the amount used for a new seeding. Kentucky bluegrass should be applied at 1-2 lbs. per 1,000 sq.ft. and tall fescue at 3-4 lbs. of seed per 1,000 sq.ft. When working with small amounts of seed, mix sawdust, dry sand or any other suitable material with the seed to aid in obtaining uniform coverage.
Fertilization and Weed Control
Applying a pre-emergent herbicide for weed control can be done in spring, but use only products labeled for new seedings including mesotrione (Tenacity) or siduron (Tupersan). These herbicides will provide good control of annual grassy weeds like crabgrass and foxtail, yet still allow the grass seed to germinate and grow.
Do not apply the pre-emergent herbicide when you broadcast the seed. Pre-emergent herbicide applied too early is a waste because it will begin to degrade before weed control is needed and won't provide effective control when weed seeds do begin to germinate next year.
Instead, wait to apply pre-emergent between mid-April and the first week of May. Several days of soil temperatures 55° degrees F or above are required for crabgrass and foxtail seeds to germinate. Be sure the pre-emergent herbicide is in place before that time for good weed control. Monitor your local soil temperature at Nebraska Extension’s Hort Update.
For new seedings, use the lower recommended rate and repeat the application one month later.
Pre-emergent herbicide is usually combined with a starter fertilizer for new seedings. A combination application made between mid-April and the first week of May is a good way to provide fertility and control weeds at the same time.
Don’t rely solely on spring rain for germination of your turfgrass seeds. Irrigate the seeded area several times a day during the first two weeks, depending on rainfall and temperatures. Keep the top 1/2 to 1 inch of soil moist as the seedlings germinate. Taper off your watering schedule as the seedlings develop As they approach mowing height, reduce the number of irrigations to 2 to 3 per week, but water more deeply with each application to encourage deep root development.
Begin mowing as soon as possible. Mowing encourages tiller (secondary stem) development, and helps new plantings thicken up quicker. It also keeps weeds under control while the new seedlings become established. Just be sure your mower blade is good and sharp!
Watch Winter Weather Conditions
One risk involved with dormant seeding is warm winter and early spring temperatures. If warm conditions cause seed to germinate and are followed by a cold period, seedlings may be killed. Continuous snow cover provides the best protection for seeds Monitor seeded areas in mid-spring for the need to do additional overseeding, but give the seeds plenty of time to germinate.
- Dormant seeding should be done from mid-December through mid-February, but no later than March 15th. Image by Vicki Jedlicka, Nebraska Extension.
- Once seeds have germinated and reached mowing height, begin mowing right away, but be sure your mower blade is sharp! Image by Vicki Jedlicka, Nebraska Extenson.