While garden sleeps, can new grass take root? Here’s the truth about dormant seeding

Many of us dream of spring and a thick, green lawn. Mother Nature’s unpredictable weather, however, makes it difficult to pull off the perfect outdoor oasis.

The best time to overseed a bluegrass or tall fescue lawn is a narrow window of four to six weeks in September through early October.

That time-span last fall was hot and dry, which made it difficult for seeds to establish. I am frequently asked if bluegrass and tall fescue can be planted another time of year. The answer, as is often the case, is “it depends.” Dormant seeding, or seeding when plants are not active or growing, is an option.

While dormant seeding may be ideal to fill in small, bare areas, it is not the best option for overseeding large areas. Dormant seeding requires more thought and work than simply casting seeds and hoping for the best.

The key to establishing successful germination of grass seed is to make sure the seed is in contact with the soil. Prepare larger areas for dormant seeding by using a verticutter to break up the soil, just as you would in the fall. Small areas can be roughed up with a rake.

Seeds will work their way into the soil with the natural freeze-thaw cycles. The cycles create cracks in the soil into which the seed can move. This movement is enhanced when there has been rainfall or a light covering of snow as the moisture helps expand the soil. You can increase the seed-to-soil contact with a light covering of soil. This helps prevent the seed from blowing or washing away.

Cool-season grass starts to germinate when soil temperatures reach the upper 50s. Don’t expect any signs of growth until late winter or early spring. Dormant seeding offers an advantage over spring seeding as the seeds germinate sooner than if you waited for consistently warm weather in March or April.

Dormant seeding can be done anytime from December through March. Several years ago, K-State Extension conducted a study where they dormant seeded an area every month from December through March. In mid-May, the plots were evaluated for percent of coverage. The plots seeded in February and March had about 80% coverage compared to 60% for plots seeded in December and January.

Don’t expect any signs of growth until late winter or early spring. Seedlings have limited roots and are more susceptible to stress. Timely watering helps, but under stressful conditions, it may not be enough.

Spring weeds can also be a problem. Crabgrass prevention is challenging as many products are labeled for more established lawns. Broadleaf controls are limited.

In my experience, the dormant seeded grass dies out over the summer, resulting in the need to seed again in the fall. Dormant seeding may help temporarily reduce some of the bare or muddy soil conditions over the summer until seeding can be done at the recommended time.

Success will depend on winter weather patterns. Will it be dry, rainy, snowy? Good soil moisture, fluctuating temperatures that loosen the soil crust, and a nice cool start to spring is ideal. This just might be a good time to try dormant seeding. Who knows – come spring, your lush carpet of green may have returned.

Dennis Patton is a horticulture agent with Kansas State University Research and Extension. Have a question for him or other university extension experts? Email them to garden.help@jocogov.org.