The Proper Time for Preemergence & Postemergence Herbicides

With the spring season just around the corner, now is the time to utilize preemergence and postemergence herbicides.  In most normal lawn care circumstances, there are usually two applications of preemergence and postemergence.  In early March, many turf grass managers apply preemergence and postemergence to the turf areas they are trying to keep weed free.  The second application of preemergence and postemergence is accompanied with fertilizer to help the lawn get off to a great start.  This second application normally occurs in late April or early May in the Piedmont region of Virginia.

Many times, landscape contractors receive requests from clients to “get rid of all of my weeds” and the majority of the time, the requests come at the wrong time of year.  After the ambient temperature of the soil rises above 50 degrees or so, crabgrass and many broadleaf weeds will begin to grow and thrive.  Therefore, it begins to be easy to understand why the first application of preemergence and postemergence take place early in the year.  This is not to say that there are no effective ways to remove weeds from your turf grass later in the year but a well thought out plan would include starting in the spring of the year.

The use of herbicide(s) should not take the place of a sound Intergrated Turf Management program.  A good turf management program includes the proper nutrients for your lawn, correct mowing techniques, a well timed aeration program later in the year and proper watering and drainage.  In addition, when it is time to plant any turf area, it is important to use certified seed and a seed type that is recommended for your lawn and the conditions that are present (shade, high sun, etc.).

It is important to note that when weeds and grass compete, weeds are going to win.  Many weeds have the ability to emit poison that will actually kill most types of grass.  Broadleaf weeds many times create shade, etc. that most grass varieties do tolerate well.