Late February is the time to get ahead of the spring & summer weed invasion before it begins. A pre-emergent is the first step in this planned attack. And the word “pre-emergent” is the key point in this plan.
Pre-emergents must be applied BEFORE weeds emerge in the spring. Timing is when soil temperatures are consistently above 55° F. In Rockwall County, this usually occurs two weeks before the last average freeze which is March 15th. This is why it is necessary to act quickly before weeds have actively taken root.
A few points to know…
Before you head to the store, one should know which weeds a spring pre-emergent program will control. All pre-emergents act the same way. They chemically prevent seeds and young plants from growing. The henbit, poa annua, and dandelions that you see today, germinated back in the fall. Perennial weeds that come back from their root systems (nutsedge, Johnsongrass, and dallisgrass) will not be affected. But crabgrass, spurge, and fall aster are still out there waiting to take hold. Rockwall County has many months of weed growth ahead. Although you see dandelions today, thousands of summer weeds are waiting for their chance to emerge.
Additionally, consumer products rarely address BOTH annual grassy weeds (crabgrass, goosegrass, sandburs) and broadleaf weeds (spurge, chickweed, fall aster). To prevent all annual weeds, one would need two different applications of pre-emergent to address both weed types. Since Texas summers are long, a second application will be needed in June to be successful. Obviously, this is time-consuming and expensive. If you know the weeds that you wish to control, focus on the prevention program to address that weed. It’s easier to spray broadleaf weeds* after they have emerged than it is to kill grassy weeds that have developed. If one had to choose, use a pre-emergent that is effective on grassy weeds since they are more difficult to control. Read the label of the product to know which weeds will be targeted.
 Chickweed |
 Spurge |
 Fall Aster |
 Crabgrass |
 Goosegrass |
 King Ranch Bluestem |
Do pre-emergents address only lawn weeds?
Pre-emergents all work the same way. They chemically prevent a seed from germinating. They stunt young vegetation from maturing. These products do not discriminate. They prevent weeds; but also, flowers, vegetables, and most plants that they encounter. So be careful to avoid over applying into areas where you want to plant a garden or flower bed; or, where you plan on reseeding an area of the lawn that might be thin.
What about weed-and-feed applications?
For the spring application, a weed-and-feed product achieves one thing: they “feed…the…weeds.” Temperatures required for turf grass to grow are a few weeks away. The only thing growing in the lawn right now are the weeds that have already taken root. Attack the weeds now. Feed your lawn in April when it is warmer.
Should I call my lawn care professional immediately?
Fear not. If you are on a seasonal lawn care program, professionals have access to different products than the average consumer. Those products have different application rates and allow for a wider window to treat weeds than the home gardener does.
* Use a product designed for broadleaf weed control in St. Augustine. Sprays formulated for use on Bermuda and other lawn grasses can kill the wider blade leaves of St. Augustine.