Straight From the Orient
The Amazing Zoysia Grass

Zoysiagrass, often spelled zoysia grass, originated in the Orient and was brought to the U.S. in the late 1800’s. Commonly called zoysia for short, it is popular throughout the transition zone and is often viewed as a status symbol for home lawns. There are three major species: Z. japonica, Z. matrella and Z. tenuifolia.

Between the three species and the various cultivars, zoysia has one of the broadest adaptation ranges of any warm season grass. Some varieties can survive the hot, humid climates of the deep south, while others can be found up to the Canadian border. The Z. japonica variety can survive the severe winters of the northern states without injury. However, in the northern ranges, the growing season is so short that it will be dormant longer than it will be green. Click here to see a map of the turfgrass adaptation zones.

Zoysia grass is often seen on golf courses, sports fields and other high traffic areas and has one of the highest wear ratings of any turf species. It spreads by the production of rhizomes and stolons which allows it to fill in damaged areas. For more helpful information on how grass grows, see the page on Plant Structure.

Zoysia grass also has one of the lowest nitrogen requirements of any turf species. It is safer on the environment and easier on the pocketbook since it needs less fertilizer than other grasses. Other major benefits of this grass is its excellent drought and salt tolerance.

The Three Primary Species of Zoysia Grass

The most commonly used species is Z. japonica. The variety Z. japonica, sometimes goes by the name Korean (or Japanese) lawngrass, and has a coarse leaf texture. It has exceptional cold tolerance and can be started from seed. Z. japonica doesn’t do well in the south, so its southern range stops about half way into the transition zone.

Z. matrella came to the U.S. from Manila in the Philippines. It is a warmer climate grass, but can survive in the northern sections of the transition zone. It has finer blades than japonica, good shade tolerance, but poor cold tolerance. It will go dormant after a couple hard frosts. In full sun, it forms a thick, hardy turf and must be started vegetatively.

Z. tenuifolia has the poorest cold tolerance of all the zoysia species. Tenuifolia also has the finest blade textures of all the species, which many people find desirable. One of the most beautiful Zoysia grass species is the Z. Emerald variety. It is a cross between Z. tenuifolia and Z. japonica. The Z. emerald variety maintains the fine blade texture of tenuifolia, but slightly better cold tolerance. It is a favorite for many homeowners.

Starting a zoysia grass lawn from seed is a slow process, much slower than starting other grasses from seed. Even if you are using zoysia grass plugs, the rate of establishment can be quite slow.

There are a number of cultivars that have been released in recent years. One of the most popular cultivars is meyer Zoysia, also called Z-52. The meyer variety is an improved variety of zoysia japonica. It has good cold tolerance, medium leaf texture, medium green color, grows well in partial shade and spreads fairly rapidly. It must be started vegetatively.

A Special Note About Z. Meyer

You may have seen in newspapers and magazines, some years ago, an advertisement for a “super” lawn grass. Many claims were made about it, such as, being almost fool proof, easy to care for and able to grow anywhere. “Just plant the grass plugs, and soon, you will have a beautiful, indestructible lawn”. What they were selling was meyer zoysia grass plugs. Although meyer is a good variety, it can’t do all that the ads promised and had no mention of its preferred adaptation range or any negative characteristics.

Advantages and Disadvantages of Zoysia Grass

Advantages of Zoysia grass

All the zoysia grass varieties will either be a primary species or a hybrid of one or more of the three primary species. Since they all have different cold tolerances, textures, and speed of establishment, it is best to check with your local extension office to see which ones have the greatest success in your specific area.

Zoysia is a beautiful turfgrass that grows well in a variety of climates. It forms a dense turf and is considered to be one of the most wear resistant of all grass species. However, if the site is to have exceptionally high traffic that will wear down the grass, zoysia may not be the best choice. This is because of how slowly it spreads. You may find it takes too long to fill in damaged areas. Bermudagrass or another grass may be a better choice in those situations.

Zoysia grass has exceptional drought and heat tolerance. The grass curls under in drought conditions to conserve water and prevent water loss through transpiration.

Most zoysia grass species have fairly good shade tolerance. In the south, the shade tolerance is greater than in the cooler regions of the north. The photo in the left, taken in the evening, shows zoysia growing in a partially shaded location. Zoysia grass does well as long as there is several hours of direct sunlight during the day. It thins in the deeper shaded areas.

The exceptional qualities of zoysia grass is why it is used in parks, sports stadiums, golf courses and anywhere a hardy turf is required. It can be mowed to ½ inch in height without harming the grass. It has a low nitrogen requirement, only a quarter of what bermudagrass requires. It does well at 2 lbs of nitrogen per 1000/sq.ft. per year.Its high salt tolerance makes it an excellent grass for coastal regions.

Disadvantages

Zoysiagrass, like bermudagrass, will turn tan when it goes dormant, but unlike bermudagrass, it should not be overseeded with rye.

A common complaint is that zoysia is slow to establish and spread. If you are planning to establish a lawn by seed, it can take a long time. Some seeds will not germinate the first year. If started by plugs or sprigs planted 6 inches apart, it will take up to two years to fill in. If not cared for properly, it could take longer. Weed control in thin areas will be a problem until it thickens up. Sod is the fastest means of establishment.

Different zoysia grass varieties will all have different rates of establishment. Geographical location and temperature will also affect the spread speed. The cultivars, Blair Z. and El Toro Z., have a faster establishment rate than meyer Z. However, keep in mind, that even with the faster spreading varieties, it can still be slow.

Zoysia grass can spread into a neighbor’s lawn, causing problems and can even break-up a good friendship. It’s aggressive nature can displace cool season grasses. It may be necessary to put a barrier in the soil that reaches below the rhizome level to help stop the grass from spreading where it is not wanted. In the zoysia photo above, the brick sidewalk has been in place for several years and the grass has never crossed to the garden on the other side.

Zoysia is considered to be a high maintenance turfgrass. The mowing frequency that is needed for it to look its best, thatch build up and spreading issues, must be considered before planting. It can become quite weedy during dormancy until it greens up in spring.

Maintenance Requirements and Lawn Care Tips

Irrigation

Zoysia is a drought resistant grass, but without rain, it will need to be watered with at least 1 inch of water a week during the summer. If the soil is sandy, it may require water every other day. If the soil is loamy or has a good percentage of clay, watering once or twice a week may be enough. If the grass has a lot of thatch, the water may not penetrate to the roots. Dethatching will be in order if that is the case.

While the grass is dormant during the winter, it will still need to be watered occasionally to keep the grass from thinning in the spring.

Mowing

Zoysia can be mowed as low as ½ inch. At this height, a very level soil surface is required so there is no scalping. This level is usually performed only on sports fields.

Many homeowners will mow the grass about once a week or whenever they feel it is in need of it. Regardless of how high you set the blade, mowing twice a week or every 5 days will keep your zoysia grass looking its best.

Using a reel mower will give the best results, but a traditional mower with sharp blades will provide a nice look. Zoysia can become very thick, so sharp blades are essential. The thicker the grass, the more strain on the mower. Sharp blades are essential for a clean cut.

Thatch

Zoysia grass has the tendency to produce heavy thatch. Thatch is not soil, but an organic layer that develops between the soil and grass vegetation, consisting primarily of shed roots and other grass debris. Over fertilization only contributes to the growth of thatch. Grass will shed its root system twice a year. It does this a root at a time, growing new roots to replace the old ones.

Thatch can be harmful in many ways. The grass roots can’t tell the difference between thatch and soil, so new roots will often grow in the thatch. Thatch is a spongy material and dries out must faster than soil, robbing the roots of needed water. If it completely dries out, it can become hydrophobic. This means water will not penetrate, but instead, will pool on the surface of the thatch. Fertilizers, pesticides, and herbicides often become trapped in the thatch, never reaching the soil. Tests have shown that almost 100% of insecticides become trapped in heavy thatch. This can also prevent the insecticides from controlling the target insects.

Annual core aeration opens up the soil allowing water and air to reach the root zone. Rent the heaviest core aerator you can find. The very thick grass, thatch, and root system can be hard to penetrate and will need a heavy machine to do the job effectively. Leave the cores on the soil to break down naturally. As the cores break down, they feed the soil micro-organisms. Top dressing is the process of scattering organic matter over the surface of the soil. A thin layer of quality organic matter will also help feed the beneficial micro-organisms that feed on the thatch. If needed, vertical mowing or dethatching machines can be rented to tear out the thatch.

Burning

In rural areas, it is common to see homeowners set the grass on fire in the spring, a few weeks before the grass comes out of dormancy. This is done when the grass becomes too thick and thatchy. There is no permanent injury to the turf and grass growth begins on schedule as weather warms up. If you decide to burn, make sure it is okay to do this where you live and make sure you have a hose ready just in case. Be sure to tell your neighbors what you are doing. If you don't, believe me, they will freak out when they see your grass burning.

Fertilization

Zoysia grass has one of the lowest nitrogen requirements of any turfgrass. It is certainly the lowest of any turfgrass of this quality. Zoysia needs to be fertilized 3 times a year.

Zoysia will do well at 2 to 3 lbs nitrogen per 1000/sq. ft. per year. In warmer climates, if the grass remains green all year, add another lb of nitrogen per 1000/sq. ft. to the annual requirement.

Go to the fertilization section to see how to apply the correct amounts of fertilizer.

2,4-D herbicide problem

There is a narrow time period when no 2,4-D (Dichlorophenoxyacetic acid) herbicide should be used on zoysia. The time period is at the point when the zoysia is emerging from dormancy. 2,4-D is one of the most commonly used broad-leaf weed herbicides and is found in such products as “Weed-B-Gone” and “weed and feed” products. If sprayed on the grass during this time, it can harm it. Other weed control products, if necessary, can be used instead. After the grass has emerged from dormancy, it is then okay to use a 2,4-D product.

Insects

Fortunately, zoysia isn’t bothered by too many insects. If they do become a problem, you will find that the white grub is generally the most damaging. White grubs are the larva of the June beetle and feed on the grass at the soil level. Evidence of white grub damage is when the grass appears cut at the soil line and can be lifted up like a carpet. Large sections of the lawn can be damaged.

A good biological control for grubs, sod webworms and cut worms is the microbial insecticide called “Baccilus Thuringensis”. Once it is consumed by the insects, it kills by producing toxins within the gut.

Mach 2 is another biological control that uses Halofenozide as the active ingredient. It interrupts the pupation stage of grub larvae without harming beneficial insects. This product needs to be applied well in advance of any damage. It will have no effect if applied at the time insects are damaging your lawn. If you have had problems with grubs before, you will probably have them again. It means you have the type of soil the adult June beetle are looking for to lay eggs in.

Quick kill products include trichlorofon (dylox) and carbaryl (sevin). Be aware that thatch can hinder the movement of insecticides to the root zone where grubs live.

Some pest controls, including some biological controls, are available only to certified pesticide applicators. Many commercial applicators will apply what you need without selling you a whole program. Check with those in your area to see.

Diseases

Brown patch is probably the most damaging disease. Rust and leaf spot can also cause problems, but they are usually not too serious.

Brown patch occurs in the hot, humid, wet periods of summer. It begins as a 1 foot patch and can enlarge to several feet in diameter. The lesions that appear on the grass become tan in appearance as the grass tissue dries out. Webby mycelium often appears on the grass on damp mornings. Avoid applications of nitrogen fertilizer and well as weed control products when the disease is present. It will only feed the fungus. As the humidity decreases and the soil dries out, the disease subsides, and the grass usually recovers. As long as the grass crown is not affected, the grass will grow out of it. If you live in a section of the country where high humidity is the rule and not the exception, fungicides, such as Daconil, are available to help control brown patch. Fungicides must be applied in the early stages of disease development for best results.