How to help lawns become healthy after last year’s drought
"Growing Together" columnist Don Kinzler says the generous spring moisture has helped, but some lawn damage from 2021 could still be present as the summer begins.
FARGO — Can you hear it? Lawns are giving sighs of relief, as generous spring moisture gives grass a long, cool drink after last summer’s parched heat.
Plentiful moisture is a great start, but many lawns were badly damaged by last year’s drought, and water alone can’t resurrect grass from the dead. Now that lawns are turning green, we can assess what is dead, what needs repair and what we can do to reinvigorate our lawns and nurse them back to health.
Let’s back up a little. Late last summer, parts of the region began receiving good rainfall, and many lawns that had entered drought-induced dormancy revived, turned green and were able to reenergize themselves before winter. Some lawns recovered totally, while others were left thin, or with dead patches.
Not all areas received rain, though, and lawns that were still dormant from drought when winter arrived might not be alive this spring, or might be very thin.
The following are methods to bring lawns back to health:
- Patience is needed, which I can’t emphasize enough. A healthy lawn results from doing seemingly small things consistently over several years to create a deeply rooted, thick, energetic turf. Creating a dense, healthy lawn, whether or not it’s been drought-damaged, depends on how we mow, how we water and how we fertilize year after year.
- If grass was thinned by drought, Kentucky bluegrass lawns can self-heal if there’s a green grass plant at least every 2 inches, because bluegrass has the ability to spread sideways by its vigorous underground rhizomes, meaning it can fill blank spaces in the lawn. If there is a green grass spear about every 2 inches, the lawn will fill back solid with moisture, nutrients and time.
- Most lawns benefit from raking in spring when the lawn has dried enough so tender grass plants aren’t torn up. Power-raking, also called dethatching or vertical mowing, should be used with caution on thin lawns to avoid damaging weak grass plants. If lawns are hard-packed and in need of aeration, core aerating can be a less invasive procedure, removing small cores of thatch and soil, allowing water and nutrients to penetrate the turf.
- Fertilize when the grass is green and actively growing, with a recommended timing between mid-May and Memorial Day. This provides nutrition for healthy roots and vigorous fill-in of weak turf.
- Some areas within a lawn might be dead. If no green grass spears emerge by mid-May, reseeding those areas might be necessary.
- Overseed thin lawns and bare patches with a grass seed mix containing at least 50% Kentucky bluegrass cultivars. First, rake the areas, sow the seed, then lightly rake the seed into the soil so some seed is still visible. Keeping the surface continually moist throughout the germination period until new seedlings are visible is the key to success.
- Mowing high will be more important this year than ever. Set the mowing height to 3 inches, which provides more leaf area for photosynthesis and energy building. Lawns mowed lower than recommended will have greater difficulty recovering from drought, suffer greater evaporation and have more weed problems.
- Allow clippings to filter back into the lawn instead of bagging. Grass clippings provide nutrients, keep the turf cool, conserve moisture and diminish weeds.
- Weeds, which by their nature are deeply rooted and aggressive, took advantage last year and quickly spread in lawns thinned by drought. Weed control will be important in May and June, and liquid herbicides are usually more effective on broadleaf weeds than granular weed-and-feed products. Spot-spray weeds instead of applying chemicals where no weeds exist, always reading and following directions on the label.
- Crabgrass, which is an annual weed growing from seed each year, can be controlled with crabgrass preventers applied before soil temperatures reach 50 degrees Fahrenheit, or after germination with crabgrass “killers” applied when crabgrass seedlings are very tiny.
- Moisture is plentiful now, but if conditions turn dry and you opt to water, water deeply and less often to encourage deep healthy roots. Frequent light sprinklings create a shallow, water-addicted root system. Lawns grow best if they receive 1 inch of water per week, either from rain or sprinkling, in one application, or split between two if the soil is sandy. A straight-sided soup or tuna can is an easy way to monitor how much water is being applied, as sprinklers vary greatly.
Don Kinzler, a lifelong gardener, is the horticulturist with North Dakota State University Extension for Cass County. Readers can reach him at firstname.lastname@example.org.