- 1). Cut your Bermuda grass lawn to its maximum recommended height of 2 ½ inches to block light from reaching the crabgrass seeds, which depend on the sun for spring germination.
- 2). Irrigate established Bermuda grass when its blades wilt. Apply 1 inch of water at that time in one single session to reach 4 inches under the surface. This practice is unfavorable to crabgrass, which thrives when irrigation is frequent and superficial.
- 3). Fortify your Bermuda grass lawn with ½ lb. of nitrogen per 1,000 square feet in May and again in July. Irrigate the grass after you finish to water the fertilizer in. Reduce the amount of nitrogen by one-fourth if you leave your grass clippings on the lawn after mowing it.
- 4). Control crabgrass with a pre-emergence herbicide applied to cover the entire lawn area after it becomes green in spring, but before the weed seeds germinate. Contact your extension office or a local nursery to get a date estimate for your region. Use a formula containing benefin or a blend of benefin and trifluralin. Colorado State University Extension also rates prodiamine and pendimethalin as excellent pre-emergence herbicides against crabgrass. Apply the chemical following the manufacturer's instructions for the brand you selected.
- 5). Spray a post-emergence herbicide while crabgrass is still young in late spring to early summer. Use a product made of the chemicals MSMA or DSMA, applying it directly to the weed according to the manufacturer's directions. Repeat the treatment five to 10 days later.