Crabgrass Control

Crabgrass is a weed that grows vigorously in hot, dry conditions. In the fall, it produces numerous seeds that will germinate and cause a problem next year and in future years. Seeds can stay dormant in the soil for many years, so controlling crabgrass could take several different approaches. Applying a pre-emergent herbicide, such as Scotts Crabgrass Preventer, helps by creating a barrier that does not allow the seeds to germinate. The lawn should receive ¼ to ½” of water within 2-3 days after the application. The first crabgrass application should occur 12 weeks prior to a weed control application. A second application of crabgrass preventer can be applied four weeks after the original application. To be effective, preventative applications must be complete by the end of April. If you have not already applied an application of crabgrass preventer by then, do not try to put a second application down; the second application will not be effective if it is applied too late. Do not exceed more than two applications of crabgrass preventer per year. 

Mowing your lawn at the proper height will help reduce crabgrass, especially in conjuction with a chemical preventer. An added benefit to proper mowing height is a thicker lawn. A general rule of thumb for a Connecticut lawn is 2 to 2.5 inches in the spring and fall, and 2.5-3 inches in the summer, while never removing more than a third of the grass height at a time. A taller, dense lawn also helps keep the soil cool, which works against the crabgrass. Watering deeply and infrequently is important to developing a deep root system. Mornings are the best time to water and it should be done one to two times a week. A lawn should receive no more than an inch of water per week, provided through irrigation and/or rain. Proper fertilization throughout the year will help encourage a healthy lawn. Avoiding excessive fertilization July through September can help in reducing crabgrass problems. Be sure to consult with one of our lawn experts to help develop a proper fertilization program for your yard. Consider testing your soil to find out what nutrients are needed in your yard in particular. UConn offers a comprehensive soil analysis for $8; kits can be picked up at the register and sent in by mail. Results will be mailed to you after a few weeks. Overseeding in the fall is another way to encourage thicker grass. This is done by adding a light application of grass seed to an already established lawn. Weeds will then have a harder time competing against a well-established lawn.