What can I do now to prevent weeds in my lawn?



You can’t see them, yet they are there — lurking just under the surface of your lawn. They seem to know that if they lay low long enough you will forget about them until it is too late. Then, one carefree summer day when you are admiring your landscape, sipping a lemonade as you wait for guests to arrive, they will strike right where it hurts — the front lawn. Unfortunately, once they rear their ugly heads there is not much you can do. Annual lawn weeds hide out until around mid-June, and by then it is too late to do anything. Annual weeds include crabgrass, spurge and foxtail. They germinate when the soil warms, but lay in wait until just the wrong moment to get big and ugly. Because they hide so well in the spring, you hardly know they are there until it is too late. Since annuals die off in the fall after the first freeze, we tend to forget about them until the first barbeque of the season. Many things can be done to minimize numbers and problems with annual weeds. However, they must be done before you actually see the weeds. Once they are established you are reduced to making excuses and living with them until the next year. Careful attention can help reduce most weeds in the lawn, whether they are annual or perennial. Consider these tips. Mow the lawn 3 inches tall. This helps shade out weeds and reduces their ability to germinate. Cutting it too short allows light to penetrate easier to the soil and encourages weeds to germinate and grow. Irrigate the lawn properly. Do not over-water. Most weeds are better competitors than grass when a lawn is over-watered. Water deep at infrequent intervals. Keep the lawn healthy and thick. This includes a good fertilization program and aerating the lawn once or twice a year. Fertilizer provides plenty of nutrients to the lawn so it can grow thick and strong, and aeration reduces soil compaction so water and nutrients can penetrate to the roots. After treating the lawn like it is king of the property, a few persistent weeds may still survive. At that point, purchase a pre-emergent to help control them. A pre-emergent is a chemical that is applied to the surface of the lawn before weeds emerge. Most come in a granular form which is applied using a spreader. A pre-emergent is a selective herbicide that kills small annual weeds after they germinate, but before they get established. It is poisonous enough to kill small, devious annual weeds, but does not create problems with already established plants. A pre-emergent controls most annual weeds; however, it does not control perennial weeds. Some examples of perennial weeds are dandelions, clover and bindweed. A pre-emergent will not bother them, but can help prevent a new crop from getting established. For example, a dandelion already growing in the lawn will not respond to a pre-emergent. However, an application can prevent any new seeds that landed in your grass from sinking their roots into the landscape. There are a number of pre-emergent products on the market, and most are very effective. Some can be applied once and are effective the entire season, while others must be applied twice, once now and again in about 60 days. Ask your local nursery or garden center which pre-emergent is carried and recommended. Regardless of which pre-emergent you choose, now is the time to apply it. If weeds were there last year, you can be sure they are already plotting to germinate and pounce again this year.

Posted on 1 Apr 2004

Jerry Goodspeed
County Director, Horticulture Agent, Weber County

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