Crab grass season is in full swing here in Kansas, or at least the seed heads are in full swing, waving in the breeze and shaking off hundreds of seeds for next year. Trying to remove or kill the plants at this point is mostly futile, so save the energy to beef up preventive measures.

There are two types of crabgrass: smooth and large. Smooth crabgrass is the most common and grows in short, spreading clumps. The leaves are soft, a little fuzzy and lighter green than most lawns. You will see it the most along curblines or growing in compacted areas, bare spots, and especially dry locations where other plants have a hard time surviving. Crab grass grows well in these areas because it can withstand the harsh conditions but also because it is a poor competitor with other plants.

Large crab grass is also clumpy and spreading but gets a little taller and resembles a gangly cousin of smooth crab grass. It grows in the same places.

Both kinds of crab grass are annual grassy weeds, meaning that plants only live one year. The plants you are seeing right now will die in a month or two even if you do nothing.

The hundreds of seeds this year’s plants dropped will mean even more crab grass next year though, unless you take preventive measures.

In the garden or landscape, mulch is the best bet. A 2- to 4-inch layer of organic mulch prevents sunlight from reaching crab grass seeds and stimulating germination. Crab grass seedlings that do appear are most easily removed in the seedling stage by hand or with a hoe or other tool. Placing plants close together (where possible) helps desirable plants shade and outcompete crab grass. Groundcover plantings are another option.

In lawns, crab grass is unable to compete with a thick stand of grass. This is why in many situations crab grass is only found in the above-mentioned tough spots. It will continue to grow here until the sites are remedied. For cool-season lawns, mid-September through mid-October is the best time to improve the stand of grass to get it healthy for next year.

Core aeration reduces compaction and allows air and water to better reach plant roots. Rent a core aerator from one of the local rental or hardware stores, or hire a professional. Make sure the aerator is run over the entire lawn twice, in two different directions (ideally making an X over each other).

Overseed with high quality grass seed, and fertilize in September and November. If the lawn has excessive thatch, use a power rake or dethatching machine. Thatch is most likely to be problematic in heavily irrigated and fertilized lawns.

If the mower is set at less than 3 inches from the ground, raise it to 3 inches or even 4. Taller grass is healthier and will grow slower, meaning fewer weeds and less mowing.

There is a lot of focus on applying crab grass prevention products in the spring. Crab grass prevention products can be one tool towards lessening the amount of crab grass in a lawn or landscape, but the products are ineffective if the timing is off or if the product is applied incorrectly. Good lawn and garden management practices are much more effective.

— Jennifer Smith is a former horticulture extension agent for K-State Research and Extension and horticulturist for Lawrence Parks and Recreation. She is the host of “The Garden Show.”