Controlling Weeds in your Lawn

The most effective method of controlling lawn weeds is to maintain a dense and vigorously growing turf cover. Increasing numbers of weeds are often an indication of problems in the grass plant’s environment that create less than favorable conditions for it to grow. Killing the weeds without correcting the underlying problem will lead to unsatisfactory results. Often, lawn weeds can be controlled simply by altering the cultural practices to favor the grass plants rather than the weeds. Cultural controls may include raising (or lowering) the mowing height, changing the frequency of mowing, lengthening (or shortening) the period between irrigations, increasing (or decreasing) the application of fertilizer or aerating the soil. A combination of proper cultural practices plus prudent use of pre- and post-emergent herbicides is a good approach to controlling lawn weeds effectively.

clover.pngPre-emergent herbicides are most effective against annual weeds that come back from seed every year such as crabgrass and quack grass. It’s important to remember that a pre-emergent herbicide does not kill the seed prior to germination. The seed must start to grow and sprout such that when the newly emerging root, shoot or both contact the herbicide they are killed. To be effective, apply pre-emergent herbicides before you expect weed seeds to germinate. In a typical year, apply pre-emergent herbicides from late March to May or once soil temperatures in the top one inch or so are consistently in the 55° to 60°F range as measured early in the day. Pre-emergent herbicides must be watered into the soil to be effective. Depending on the soil type, ¼ to ½ inch of moisture should be applied following application of these products. We offer a pre- and post-emergent crabgrass preventer, Green Pro Crabgrass Preventer, that allows for up to 180 days of control preventing the crabgrass from sprouting a well as controlling it at the 2-3 leaf stage.

Post-emergent herbicides are used to kill weeds when they are young and growing vigorously or in the fall when perennial weeds dandelions.pngare storing food in their roots for the next year. Green Pro Weed ‘N’ Feed with Viper™ is our post emergent herbicide that controls over 250 broadleaf weeds including such dandelion, clover, ground ivy (creeping Charlie), knotweed and plantain. Post-emergent herbicides can be applied anytime during the season, but many people tend to apply it 6-8 weeks after a crabgrass preventer, typically sometime between April and June. They are usually most effective when absorbed through the leaves of the weed, so we recommend post-emergent herbicides should be applied when there is a heavy dew or right after it rains. Consequently, you shouldn’t water your lawn for 48 hours after you apply herbicide because heavy rainfall will wash off the herbicide.