Pre-emergence Herbicides- Prevention Better than Cure

Have you ever felt frustrated by seeing weeds growing in your lawn? Every spring, you apply so many gallons of herbicides; the weeds go away briefly, and suddenly, they return. Winter weeds, such as Florida Snow (Florida Pusley), decorate your yard with white flowers. As the old saying goes, an ounce of prevention is better than a pound of cure. It is better to prevent weeds from growing in the lawn than to try to control them.

The good news is that many weed species are annual plants, and pre-emergence herbicides are available to prevent annual weeds from taking over your lawn. Pre-emergence herbicides do not prevent the weeds from germinating but kill the plants after germination. Applying pre-emergence herbicides is good practice. It eliminates the use of large volumes and the frequency of post-emergence herbicides. Post-emergence herbicides for controlling grassy weeds in St. Augustine are very limited. Often, the herbicides that kill grassy weeds will also damage St Augustine. It’s best to apply pre-emergence to prevent weeds in St. Augustine rather than trying to control them later.

Pre-emergence is only effective before weeds emerge. The perfect time to apply pre-emergence herbicides is before your area experiences a temperature of 65–70 degrees Fahrenheit for five days consecutively.  The recommendation to apply pre-emergence based on location is: South Florida, apply around February 1st; Central Florida, February 15th; and North Florida, March 15th. Applying pre-emergence later than the recommended date may reduce its effectiveness. For pre-emergence information, please visit the link ENH884/EP141: Weed Management Guide for Florida Lawns ( Grantly Ricketts, UF/IFAS Extension Commercial Horticulture Agent, wrote this article. Grantly can be reached at or by phone at 772-462-1660.


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Posted: February 2, 2024

Category: Horticulture, Lawn, Turf
Tags: Pre-emergence

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