Alternative to Corn Gluten for Crabgrass? Try Compost
The interest in corn gluten meal as a pre-emergent weed control for crabgrass and other weeds continues to amaze us here at SafeLawns. Our post on the subject was easily the most visited of the year thus far. And since we’re not big fans of corn gluten meal, especially given the cost, loads of folks want to know about an alternative crabgrass preventer that doesn’t involve toxic chemicals.
The answer(s) all involve one simple premise: crabgrass seeds need a burst of direct bright light to germinate. Remembering that should be at the core of all your crabgrass control strategies. Here are the the considerations:
1) TOP-DRESSING: Blanketing the surface of the lawn soil in the spring with compost or even topsoil will keep crabgrass seeds from germinating. We recommend covering the lawn with a half-inch layer of bulk compost and then overseeding with grass seed directly into the compost. The grass seed will germinate and the compost will give the lawn a layer of nutrients, moisture retention and a biological boost.
Topsoil doesn’t have quite the same nutrient and biological value as compost, but it will serve the purpose of blocking the crabgrass seeds. And adding more soil to your lawn is never a bad thing.
If you have spotty areas of the lawn that are thin, without much grass, it’s especially important to cover these. Otherwise you can virtually be assured that opportunistic crabgrass and other weeds will take over.
2) AVOID SPRING RAKING: If you have patches of leaves and debris left over from last fall, you need to rake them off the grass. When you do so, however, try to avoid really scratching the surface of the soil. This activity brings crabgrass seeds to the surface, where they’ll easily germinate.
If you feel it’s necessary to really grind when you’re raking, then it becomes imperative to back to point number one and topdress with soil or compost.
3) AVOID MOWING: Keeping in mind that crabgrass seeds need light to germinate your mowing height and frequency are perhaps the most important consideration of all. Mowing too low anytime in the spring and summer will almost assuredly bring more visible crabgrass in the late summer and fall. Tall grass plants shade the surface of the soil so that the crabgrass doesn’t germinate; tall grass plants also conserve moisture in the summer. A good rule of thumb is to keep the grass at least 3 inches tall until after Labor Day.
4) WATER AS INFREQUENTLY AS POSSIBLE: Old-timers called crabgrass water weeds because they seemed to appear instantly after frequent or heavy rains. Constant watering of the lawn causes soil erosion around the seed, thereby potentially exposing the seed to light.