No easy answer to setting mower height

In answering gardening and horticultural questions for 25 years, I’ve found one thing rings clear: most people are looking for a quick fix or a one-size-fits-all answer. 

I often see this when it comes to questions about mowing heights. Along the Gulf Coast, we have three distinct turfgrasses - St. Augustine, Bermuda and zoysia, and one mowing height doesn’t apply for all. In fact, one height doesn’t even apply to all St. Augustine varieties. Or all type of zoysia. Plus, mowing height is also determined by the health of your soil. And not everyone has the same type of mower, either.

So, frankly, you have to experiment with mowing heights.

If you have a mowing service doing the work for you, you’ll need to get them to raise their mower decks. I’ve found there are two ways to make this happen. First, call the owner, manager, or coordinator and tell them you want the mower height (riding or push) to be raised at least one notch above their normal setting when they get to your place. If they refuse or claim they can’t, fire them and find a crew that will.That’s pretty simple. Or you can do what I’ve done: be on hand when they arrive and ask them politely to raise the mower deck at least a notch. And be out there to do that for two or three consecutive weeks. Eventually they’ll learn to habitually make the adjustment when they arrive at your house. 

Now, I do have a few rock-steady rules you can apply starting this week. But please feel free to make some adjustments.

• For St. Augustine mow your grass at the highest or next-to-highest setting of the mower deck
• For St. Augustine, don’t mow any lower than a 3- to 3.5-inch-high profile
• For St. Augustine in healthy soil, you can and should mow at a 3.5- to 4-inch profile
• For Bermuda grass, you can and should mow at a 2- to 2.5-inch profile

• For thin-bladed zoysia grass, mow like its Bermuda at 2- to 2.5 inches high
• For wider-bladed zoysia, you can mow like a St. Augustine at 3 inches
• Don’t rely on fertilizer manufacturers for mower height recommendations. National companies use information they’ve collected from grasses used throughout the country, and they’ve rarely studied St. Augustine. 
• Many local and regional lawn fertilizer or turf installation companies haven’t updated their information on mowing heights in more than 30 years. In that time, many varieties of zoysia and Bermuda have appeared, and you can bet all their old data is strictly for St. Augustine.  
• For Bermuda and thin-bladed zoysia grass, you should use a reel mower - one that cuts over the top – rather than a rotary mower whose blades spin like those of a helicopter.
• You’ll notice that the lower a mower deck is set for St. Augustine, the more yellow the grass will look year-round.
• The first mowing of the year can always be with the blades lowered an extra notch or ½ inch. That will open up or aerate the lawn for the coming spring.
• In autumn months, you can “vacuum up” tree leaves with a mowing if you lower the deck by ½ inch.