Expert Answers: Don’t fertilize your lawn this month!

The sun is shining and spring is in the air. Does that mean it’s time to prepare your lawn for the summer? Auburn faculty member and Alabama Cooperative Extension Services Specialist Dave Han says not quite yet! The state of Alabama is home to warm-season grasses that include Zoysia, Bermuda and Centipedegrass, and they all require the same care to make your yard look good.

Han teaches students in Auburn’s Turfgrass Management major in the College of Agriculture. He also provides support and training in turf-related areas for Extension agents across the state. He is an expert on turf management in a wide range of areas, from golf courses and athletic fields to parks, sod farms and professional lawn care. Han, who holds bachelor’s and master’s degrees from Cornell University and a doctorate from Ohio State, serves as the educational advisor to the Alabama Turfgrass Association.

 

It’s March and the weather is warming up. Why can’t I fertilize my lawn yet?

Warm-season grasses need hot weather in order to grow their fastest and use fertilizer efficiently. The weather in March is often pleasantly warm in the daytime but dips into the low 50s or 60s at night — and that’s just not warm enough for Bermuda grass, Zoysia grass, Centipedegrass or St. Augustine grass to grow fast. It will turn green, but it’s just kind of sitting there instead of growing. Last March, we had a few days in the 80s, but we also had nights in the 40s.

Also, the soil temperature generally doesn’t get to about 70 degrees in March, and that’s the threshold for fast growth.  

So, when can I fertilize? 

A good rule of thumb is to fertilize when the high and low temperatures add up to 150 or more. For example, when daytime highs are around 85 and overnight lows are 65, you know it’s time. And if we’re getting technical, you can fertilize when the soil temperature at four inches deep hits 70 degrees.

If I have to wait to fertilize, what should I be doing to my lawn right now?

It’s hard, but there’s not much you can do in March. We have to wait until the end of the month in most of Alabama to be past the average last frost date, and it is certainly not unheard of to get a freeze in April either, especially in north Alabama. Honestly, the best thing to do in March is make sure your irrigation system, if you have one, is in good working order.

When should I do a routine soil analysis through Auburn’s Soil, Forage & Water Testing Laboratory?

Any time! You won’t want to begin fertilizing until it’s warmer, but lime can be applied any time if it’s needed. And you’re not busy yet with other things, so now is a good time to sample for a soil test.

What’s the rule of thumb for when to start mowing my lawn?

You probably won’t need to mow in March, but that will depend on the weather. As soon as it's growing enough to need to be mowed, that’s the time to start.

What does aeration do, and how often should I aerate? 

Aeration helps to reduce soil compaction, allow for better water drainage and ensure enough air can enter the soil to allow for good root growth. How often you aerate depends on your soil and how much traffic there is on the lawn. If growth isn’t being affected by soil compaction, then there’s no real need to aerate. But if your grass is thin and compacted, it may take several aerations to improve grass health.