Zoysiagrass Empire: half the nitrogen, twice the patience

Zoysia sits between the bermudagrasses and the fescues: it holds a 15 to 30 mm cut, runs on 10 g of nitrogen per square metre per year, and survives drought on a 150 to 250 mm root system. It also takes 40 to 60 weeks to establish and builds thatch faster than anything else here.

Establishment in weeks, not days

Empire zoysia is vegetatively propagated and establishes from plugs on a 200 to 300 mm grid, 40 to 60 weeks to full cover. There is no faster route: the species spreads by stolons and rhizomes at 50 to 100 mm a season, which is half the rate of bermudagrass and a third of the rate of a hybrid.

During that period the plugs need 25 mm of water per week and no competition. Weeds in a new zoysia lawn will outgrow the plugs by a factor of five in the first season, so a pre-emergent programme in the establishment year is not optional.

The 15 to 30 mm band and why the mower matters more than usual

The working band is 15 to 30 mm with a floor of 10 mm. Zoysia has stiff, wiry leaf blades with a high silica content, and a rotary mower tears them rather than cutting, leaving a brown, frayed tip that shows for a week. A reel mower is strongly preferred above 20 mm and effectively required below 20 mm.

Because growth is slow, the one-third rule is easy to satisfy: cut every 7 to 14 days through summer rather than every three days. The exception is the spring flush, when zoysia can produce 15 mm a day for two weeks and needs cutting every second or third day.

10 g of nitrogen and the late-season rule

Budget 10 g of nitrogen per square metre per year, split 45:25:30. That is half what a hybrid bermudagrass needs, and it is the single strongest reason to choose zoysia on a large property. On 100 square metres: 450 g, 250 g and 300 g of actual nitrogen.

Stop all nitrogen eight weeks before the first expected frost. Zoysia that goes into winter with soft late growth suffers more winter kill than any other warm-season species here, and in the transition zone winter kill on zoysia is the number one reason lawns are replanted.

Iron at 2 g per square metre in midsummer gives the deep green that visitors associate with zoysia, without the leaf growth that extra nitrogen would produce.

Thatch, thatch, thatch

Thatch tendency is 5 out of 5, the joint highest in the set, and it is worse than bermudagrass because zoysia produces lignified stolons and a dense, slow-decomposing mat at the same time as a low cut that prevents you from mulching the problem away.

Vertical mow every year in late spring once growth has started, taking 3 to 5 mm. Follow with a topdressing of 1 to 2 mm of sand. On a lawn that has never been dethatched, do not take it all in one pass: 5 mm a year for three years removes a 15 mm mat without scalping the stolons underneath.

Questions that come up on this page

Why is zoysia so expensive to establish?

Because it cannot be seeded and spreads at 50 to 100 mm a season. Plugs at a 200 mm grid cover in 40 to 60 weeks and cost several times a seeded bermudagrass lawn. The saving is in the nitrogen bill and the mowing hours for the next twenty years.

Does zoysia really need less water than bermudagrass?

It uses about the same water in summer, around 20 mm a week, but its 150 to 250 mm root system lets it survive a dry spell that would kill a shallow-rooted species. It is not lower-water, it is more drought-tolerant.

What kills zoysia in the transition zone?

Winter kill, and it is almost always caused by late nitrogen. Stop feeding eight weeks before the first frost and mow the lawn down to 20 mm as growth stops so the stolons are not smothered by their own dead leaf.

Sources

The public reference material the figures on this page were checked against:

• University of Delaware Cooperative Extension
• Illinois Extension
• Purdue Extension
• New Mexico State University