Best Practices to Stop Crabgrass Growth This Spring

By Blake Jackson

Managing crabgrass effectively should be a key part of any spring lawn care plan, but success depends on more than just herbicide use.

Bruce Spangenberg, a Horticulture Outreach Specialist with the UW-Madison Division of Extension, emphasizes taking an integrated approach that prioritizes strong cultural practices to maintain healthy, dense turf.

Last year proved especially challenging, with crabgrass spreading aggressively across many Wisconsin lawns. Poor lawn conditions after winter, followed by warm and moist early summer weather, created ideal conditions for rapid growth.

As a result, many lawns experienced heavy infestations, leading to significant seed production that can contribute to future problems.

Because crabgrass is an annual plant, it dies off at the end of each growing season and returns only through seed germination. These seeds begin to sprout when soil temperatures consistently reach between 55°F and the low 60s. Since crabgrass requires sunlight to germinate, it thrives in thin, patchy lawns where light can easily reach the soil surface.

Preventing crabgrass starts with maintaining a thick, healthy lawn. One of the most effective practices is adjusting mowing height. Keeping grass at around three inches throughout the season helps shade the soil and limit crabgrass growth.

Proper fertilization is equally important, particularly in sunny areas. Lawns should receive nitrogen applications in late spring and early fall, with controlled-release fertilizers providing the best results. Spring fertilization is ideally timed around the second mowing of the season.

Watering habits also play a major role. Frequent, shallow watering encourages crabgrass, so lawns should instead be watered deeply and less often to promote stronger root systems.

Avoid lawn disturbances during peak germination periods, delaying activities like aeration until late summer.

For lawns with a history of severe infestations, preemergence herbicides may be useful. However, they are unnecessary for lawns without past issues. Proper timing often indicated by forsythia blooms is critical for effective application.

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