Most lawns are watered little and often, and that is the pattern that makes them struggle in a heatwave. A lawn that gets a deep soak once or twice a week grows roots that reach down to moist soil, and it rides out a dry fortnight far better.
How much water does a lawn need in summer?
In a hot, dry spell, about 2 to 2.5 cm a week including rain, in one or two sessions. Sandy Sydney soils drain fast, so two smaller soakings beat one big one. Clay soils take water slowly: water for 15 minutes, pause, then water again so it soaks in instead of running off.
How often in winter?
Rarely. Warm-season grasses slow almost to a stop in winter, and winter rain usually covers what little they use. Water only after several dry weeks, and only if the lawn looks grey and wilted rather than just dormant brown.
What time of day should you water?
Early morning. Less water is lost to evaporation and wind, and the leaves dry during the day. Evening watering leaves the lawn wet overnight in humid weather, which invites fungal disease. Water utilities also restrict daytime watering, so the morning is usually the rule anyway.
How do you know the lawn is thirsty?
- Footprints stay flat instead of springing back.
- Leaves fold or curl. Buffalo leaves fold lengthways when short of water.
- The colour turns grey-green.
What are the watering rules?
Most water utilities have permanent rules on when and how you may water gardens, with tighter restrictions in drought. In Sydney that is Sydney Water’s Water Wise Rules. Check the current rules for your address before setting a timer or buying a sprinkler.
What does the app show you?
The app has no watering button and sends no reminders. It shows the rain you would otherwise guess at: the chance of rain and the millimetres expected for today and the next two days.
On this day the forecast showed almost 19 mm on its way within two days, which is close to a full week’s water. Anyone who watered that morning would have wasted it. The app also estimates soil temperature and says when the soil is warm enough that the lawn needs keeping watered.
In a hot, dry spell the app also raises the recommended mowing height, which helps a stressed lawn more than extra water. More in Lawn Mowing Height in Australia.
How is watering new turf or seed different?
New turf needs daily watering for the first week or two until the roots knit into the soil, then less often and deeper. New seed needs the top centimetre kept damp. The timing for sowing is in When to Oversow Your Lawn. What a Green Lawn keeps the forecast, soil temperature and mowing height in one place.