Garden Variety: Fall care key to creating a healthy lawn

Healthy lawns reduce erosion, slow and reduce stormwater runoff, filter pollutants, provide a cushioned surface for play, and create a frame for the landscape. Turfgrasses — the thick, mowable grasses that make the best lawns — need care though. Fall is the best time to give them attention, and fortunately even the most neglected lawns can be brought back into shape with just a little work.

Most lawns in northeast Kansas are made up of cool-season turfgrasses such as fescue, bluegrass, and ryegrass. Buffalograss, zoysiagrass and bermudagrass lawns are also suitable low-maintenance turfgrasses classified as warm-season grasses. They require the most care in the summer months.

To get the lawn into shape this fall, start with a shopping trip for grass seed and fertilizer. If the lawn is really weedy, you may be interested in weed control products. They are a tool that can be used, but how the lawn got to that point should also be considered. Most likely the lawn is weedy because of poor management. Changing management practices (mowing, fertilizing, etc.) of the desired grass will provide more benefit than any product applied to the lawn.

For grass seed, ignore pretty pictures, well-marketed brands, and all-promising names. Look for a label that lists out the contents — seed varieties, germination rates, percentage of weed seed included, inert matter and test dates. Turf-type tall fescue is the best-suited cool-season lawn grass for the Lawrence area. Look for a bag that includes more than one variety of turf-type tall fescue over grass seed that includes bluegrass, ryegrass, and/or other fescues.

On the grass seed label, also look for high germination rates and very low weed seed percentage rates. Seed that is produced in the region may be better suited to seed produced in Oregon or somewhere else, but may be difficult or impossible to find. Finally, look at the test date. That’s the date when the seed lot was tested for bagging. Because grass seed loses viability quickly, look for recent test dates. Kansas law says grass seed cannot be sold in Kansas after 10 months past the test date, but stores often fail to rotate their inventory.

How much grass seed to purchase depends on the size of the area that needs to be reseeded. If you are filling in a few bare patches, a small bag is probably enough. If you want to reseed the entire lawn, your best bet is to know the square footage and check the label for recommended rates and coverage.

Fertilizer should also be judged by its label rather than its bag or box. There will be a string of numbers somewhere on the bag — something like 20-0-0 or 30-5-5. These numbers represent nitrogen, phosphorus, and potassium respectively. Unless you have had a soil test that recommended something different, stick with a high-nitrogen fertilizer. It may cost more than one with a lot of inert matter/fillers, but will provide greater benefit.

Organic fertilizers are as suitable as conventional fertilizers for fall lawn care and are more readily available in lawn-sized bags than they have been in the past. The benefit to using organic fertilizers over conventional (besides environmental concerns) is that they can help to build up beneficial soil microorganisms that will make the lawn ecosystem healthier as a whole.

Plan to apply fertilizer to the whole lawn. Knowing the approximate square footage of the lawn will be helpful to compare with recommended application rates from the bag and determine quantity of bags needed.

If you really want to go all out, consider hiring someone to aerate and/or verticut the lawn, or rent the equipment and do it yourself prior to overseeding and applying fertilizer. Aerating loosens soil compaction that occurs over time. Verticutting slices into the soil surface to loosen it and create a soft bed for new grass seed.

For small spot overseeding, use a rake to loosen or scratch up the soil surface to create a bed for the seed.

Once the yard is prepared, apply the grass seed and fertilizer according to package directions. If overseeding a thin yard or starting from scratch, wait until grass seedlings emerge to apply the fertilizer to get the most benefit.

Water new grass over extended dry periods this fall and early winter if necessary. Mow high (3 to 4 inches is often recommended for best turf health). Fertilize again in early November if you wish. Avoid fertilizing nonirrigated lawns in the spring as it will only stress the grass. If fertilizing an irrigated lawn, wait until May and use a slow-release fertilizer.

— Jennifer Smith is a former horticulture extension agent for K-State Research and Extension and horticulturist for Lawrence Parks and Recreation.