Caring For Your Zoysia Lawn in Hot Weather

The Australian Bureau of Meteorology has today announced the next three months across the East and North of Australia will be drier and warmer than normal.

That means a strong likelihood of your turf areas needing more irrigation than usual.  Your turf might be stressed.  How can you best handle the issues that arise?

Adequate potassium fertiliser is a wise option.  Potassium boosts stress response in plants as it helps develop better structural tissues, including cell walls, and aids plants in overcoming or being resistant to water stress, as well as the related heat stresses, even in those varieties with superior heat adaptation.

Use a fertiliser mix with adequate potassium, applied soon, or add up to 1-2 kg / 100 sq  m of potassium sulfate or even potassium nitrate as the fertiliser. You may need to look more widely for these but they are around. Slow release NPK mixes tend to use one or other of these products, but you want a potash content of around 10-15% in the mix.  Avoid muriate of potash which is potassium chloride, as it can add saltiness to your turf area.  Muriate of potash is readily available, and can be cheap, but it a short term gain that can add to long term problems.

And what about the perennial issue of mowing?

There is a tendency to mow the lawn shorter in warm weather……..as if you might be able to avoid an extra cut by doing that.

Reality is you are best to actually cut the lawn less frequently and slightly higher, when there is hot, dry, stressing weather!  Long leaf that is uncut means less water loss from the cut edges and better soil cover from the leaves that helps control soil temperature and lower water loss from both evaporation and transpiration.  When weather turns and some decent rain arrives, then you could mow at a lower height………but not too low unless you have a very strong need for a “golf green” appearance, and the mower is suitable.

Zoysia is well adapted to hot weather, and can easily adapt to mowing heights between 15 – 60mm.  It is suggested that heights of 35 – 45mm [possibly slightly more] are suitable when the weather is hot and dry.  Switch to a lower cut height [around 20-25mm] once more regular rain is imminent.  Always remember that you do not want to remove more than one third of the sward height at any one mowing.

It is better to manage your turf and even avoid too much mowing.  You can achieve a good quality zoysia turf with maybe 50% of the water demand [ currently up to 50% of the 6-8mm a day of evapo-transpiration in Darwin] applied on every second or third day] especially if the turf has good soil cover.  Would you prefer mowing weekly or every three or four weeks?  It can be done to manage water, fertiliser and mow frequency to achieve a good turf that is functional and looks good, and is mown at 4 week intervals [ but check for weeds too].

You want your turf to develop a deep strong root system that can access water from up to around 150mm [ or more] deep in the soil profile, and not the shallow 25mm deep roots promoted by short watering that only superficially wets the profile to 25 – 40mm.  

Infrequently mown zoysia as a median strip in Kuala Lumpur Malaysia

Longer, less frequent irrigation is definitely superior and aids developing a robust root system that can be functionally efficient in scavenging water.