Lawn & Tree Care Tips

Chemical lawn applications are a vital component of maintaining that picture-perfect turf that so many of us desire. Almost nothing can quite ruin the look of a lush emerald green lawn than a batch of nasty weeds. Fortunately, we have several tools at our disposal. Certainly not the least of these is pre-emergent weed control.

In essence, pre-emergent weed control products are chemical compounds that prevent weeds from growing and developing. While there are a variety of products and action classes (i.e. how the chemicals attack or affect the plant), the main idea is the same. A misnomer is that pre-emergents kill weed seeds but this is not correct. When pre-emergents are applied prior to weed seed germination this creates a protective chemical barrier in the soil. When seeds begin to germinate and develop roots, those roots are killed or stunted in the early stages of growth which prevents the weeds from growing to maturity and ultimately results in plant death. Some pre emergents have a post-emergent (kills weeds after they have germinated and are actively growing) affect on weeds, such as dithiopyr on early stage crabgrass. We also want to rotate our pre-emergent products from year to year in order to prevent a resistance build-up in weeds. But be careful – pre-emergents are not limited in preventing only weeds from growing but turf grass seeds as well! If you plan to overseed your lawn you’ll want to skip the pre-emergent application before hand, so plan ahead.

As previously stated, timing of pre-emergent applications is critical. Spring time applications are particularly important. Turf grass and weeds alike start to become active as soil temperatures begin to rise in February and March. Crabgrass will typically begin to germinate when soil temperatures hit 55 degrees for 3 or more days. For control of dandelions, Fall is the best time to apply a pre-emergent. If a pre-emergent barrier is not in place at these crucial points you may have a weed outbreak on your hands which can be very costly to treat with post-emergent products. However, simply getting started on a regular pre-emergent application schedule is much better than doing nothing at all. Applying pre-emergents every 3-4 months, or quarterly, will go a long way in controlling and reducing weeds in the lawn. Pre-emergents can also be used in flower beds, sidewalk cracks, bare soil, and many other places where unwanted weeds may pop up.

Dry and liquid forms of pre-emergents exist in the market today. Most DIY homeowners will probably use a dry granular fertilizer with pre-emergent mixed in. For dense and healthy lawns with minimal weed pressure this works great. However, for thin lawns or areas with large bare spots, liquid treatments are best. Liquid applications are going to be more uniformly dispersed versus a granule resulting in greater and more accurate weed control. I use both dry granular and liquid formulations in my lawn care programs depending on the state of the yard I am treating. My preference is liquid because I can mix it in my spray tank with post-emergent weed control products, fertilizers, etc. I apply pre-emergents in my Spring, Summer, and Fall lawn applications for optimum control of broadleaf and grassy weeds.

While pre-emergents are not the only tool for weed control, they are highly useful for helping control and reduce the amount of weeds in the lawn and landscape. Pre-emergents are typically financially cheaper than post emergent products and can help prevent bigger headaches later in the season which is well worth the expense.