Source: Kenneth Clayton, plant and soil sciences extension associate 

Spring is here, and you might be itching to give your lawn a little TLC. While many people think “it’s spring, better grab the fertilizer,” the truth is that the very best time to boost lawn health is actually in the fall. That’s when conditions are prime for the grass to build strong roots. However, one of the most important (and often overlooked) spring lawn care practices is applying a preemergence herbicide. 

If you want a thick, healthy lawn this summer, stop weeds before they even get started. If you wait until you can see them sprouting up, you’re already fighting an uphill battle. Postemergence herbicides, which you spray onto actively growing weeds later, can be more expensive and less effective. By applying a preemergence herbicide now, you’ll knock out those weed seeds before they even sprout, saving you time, energy and money down the road. 

The best time to apply is when the soil temperature at a two-inch depth averages between 50-55°F for about five consecutive days. You can check soil temperatures online through resources like Kentucky Mesonet, or use a simple soil thermometer. If you’re not into checking soil temps, another trick is to watch for forsythia blooms. When those bright yellow flowers are in full bloom, it’s usually a good sign that it’s time to apply. In Kentucky, this typically happens in March to early April. 

For the best results, many lawn care professionals recommend a two-application approach. The first should be made when soil temperatures indicate it’s time, and the second about six to eight weeks later to extend protection throughout the season. Always follow the instructions on the herbicide label to ensure you don’t exceed the recommended annual use rate. 

While a preemergence herbicide is an excellent tool for preventing weeds, it’s not a magic fix. Another great way to keep weeds at bay is by maintaining a thick, healthy lawn that naturally shades out any potential invaders. Raising your mower height can be one of the most effective ways to do this, as taller grass helps block sunlight from reaching weed seeds.  

Not every lawn will need a preemergence herbicide every year. If your lawn is already thick and weed-free, you may not need to apply one at all. However, if you’ve had issues with grassy weeds in the past or notice bare patches where weeds might take hold, it’s a good investment. If you skipped fertilizing in the fall, you can apply a moderate amount of fertilizer in the spring along with your herbicide. Just be careful not to overdo it, or you might end up feeding the weeds instead. 

Taking a preventative approach now will save you time, money, and frustration later in the season. By applying a preemergence herbicide at the right time and focusing on overall lawn health, you’ll be setting yourself up for a lush, weed-free lawn all summer long. 

More information can be found at the University of Kentucky Martin-Gatton College of Agriculture, Food and Environment publication here: https://publications.ca.uky.edu/files/AGR272.pdf. 

You can also contact your local (COUNTY NAME) Extension office for more information on how to create a successful yard this spring.   

###  

Educational programs of the Cooperative Extension Service serve all people regardless of economic or social status and will not discriminate on the basis of race, color, ethnic origin, national origin, creed, religion, political belief, sex, sexual orientation, gender identity, gender expressions, pregnancy, marital status, genetic information, age, veteran status, or physical or mental disability.    

The University of Kentucky Martin-Gatton College of Agriculture, Food and Environment news and communications team provides monthly Extension Exclusives in the categories of Horticulture, Agriculture and Natural Resources, 4-H and Family & Consumer Sciences. To see more exclusives, visit https://exclusives.ca.uky.edu.  

---

ANR