Click below to listen to my Garden Bite radio show: Lawn herbicides and fertilizers
I’ve recently had questions about how people can get rid of weeds in their lawn now and what kind of weed and feed should they do. First up – do NOT fertilize your lawn in hot weather. Yes, we are coming off the wettest July in years and are out of a drought, but we’ve also had some very hot days and will likely have more. NORMALLY, The best times to fertilize are later in August and mid-October.
Fall is the best time to control perennial broadleaf weeds. At this time of year (mid-September through mid-October), these plants are storing carbohydrates for winter, actively growing and will readily take up the herbicide. Often, a one-time, relatively low rate of application of an appropriate herbicide will be effective. Since much of the other landscape plant material is either going dormant for the winter or has been removed from the garden and flower beds, there is less chance for off-target plant injury. There are a number of broadleaf weed herbicides (weed killers) available for use on lawns. Only apply to actively growing weeds. Choices found in garden centers typically include 2,4-D (the most commonly used). It was reevaluated by the EPA in 2005. MCPP (2-(2-methyl-4-chlorophenoxy) propionic acid); or dicamba (3,6-dichloro-o-anisic acid); with two and three-way combinations available.
Could this be your lawn? clover? dandelions?
This is an extensive article by University of Minnesota Extension “Control options for Minnesota lawn and landscape weeds”
The use of corn gluten meal as a herbicide was discovered during turfgrass disease research conducted at Iowa State University. CGM was observed to prevent grass seeds from sprouting. Further research has shown that it also effectively prevents other seeds from sprouting, including seeds from many weeds such as crabgrass, chickweed, and even dandelions. Corn gluten meal [University of Minnesota extension] is effective only against seeds, not existing plants. Annual weeds that are already up and growing will not be killed by products made of corn gluten meal. They’ll die on their own, though, by the end of autumn. But most of the seeds they produce later in the season shouldn’t sprout – provided you’ve applied the CGM properly and at the correct time. Crabgrass, foxtail, purslane, and prostrate pigweed are examples of annual weeds found in lawns. CAVEAT: The jury is still out with some folks on how effective CGM is and with it’s timing issues and the current price of corn, many are opting out of this option.