Zoysia 101: Warm-season grass needs different care than cold-season grass

I looked back through all of the gardening articles I have written and failed to see anything that I published about zoysia grass. Since I have had an increase in interest about it this year, it seems appropriate to take up the subject.

Before I started this column, I tried to figure out why I had never written about this warm season grass. I like zoysia. It is a nice grass that is not as invasive as Bermuda. Then it hit me: I have never suggested zoysia as a lawn grass because of all the inaccurate hype that is given to it by mail-order nurseries. It is sold as a low-maintenance lawn that eliminates weeds and grows low so that it doesn't have to be mowed very often.

Today I will give you the real story. Zoysia is a warm season grass, so it has to be handled differently than the cool season grasses such as turf type tall fescues that most people grow in our area.

You want to fertilize zoysia very heavily when it is growing rapidly. Since it is a warm season grass, it grows rapidly during the summer. You should feed it twice during the summer, usually in June and July with a high nitrogen fertilizer such as a 24-0-4.

Do not feed it in March or early April. You may encourage it to wake up too early in the year, and a late cold spell could damage it. Nor do you want to feed it after August because you want it to go to sleep before the temperatures drop in the fall.

Don't believe the information provided in mail-order catalogs about weeds. They can grow in a zoysia lawn. Treat it in March with a preemergent for crabgrass (just don't use one with fertilizer). You will probably have to spray during the summer with a trimec compound to eliminate some broadleaf weeds that may pop up. Lespedeza is a common broadleaf that grows in zoysia.

Since zoysia is a heavy feeder and rapid grower it has a tendency to produce a heavy thatch layer. I have seen thatch layers of up to 2 inches thick (thatch is a layer of dead roots and shoots).

When a thatch layer builds up, new roots have a tendency to grow into the thatch instead of into the soil. When we go during a summer without moisture for four to six weeks, this layer dries out, and the zoysia can't get enough moisture to persevere. Thus, the zoysia declines rapidly, and weeds take over.

To eliminate the thatch buildup, aerate your zoysia lawn each spring in May with a core aerator. This will eliminate the thatch and allow your zoysia to grow well under stressful conditions.

Coaches often ask me if zoysia would be a good grass for a football playing field. They have heard that the footing on zoysia and Bermuda is better than on cool-season grasses such as fescue, blue grass or rye. I tell them not to use warm-season grasses on a football field in our area. The football season extends into October and November, a time when warm season grasses are going dormant. Football is a sport that damages turf to a great extent. Warm-season grasses are not growing in late fall, so they can't repair themselves after a football game. Cool-season grasses can. That is when they grow rapidly.

If you would like a zoysia lawn, you will need to start it with sod or sprigs. Install the lawn in May or June. Just remember you will need to rethink when you perform normal maintenance.

Send your gardening and landscape questions to Paul Schnare at P.O. Box 699, Cape Girardeau, MO 63702-0699 or by email to news@semissourian.com.