How Much to Water St. Augustine Grass (and How to Set Your Timer)

Deep and infrequent beats short and daily

Think about a good thunderstorm. The ground gets soaked, then has a few days to dry out. That's the pattern to copy. A 10-minute daily watering only wets the top inch or two of soil, so roots stay shallow. Shallow roots mean a lawn that browns the moment you miss a day in July.

Deep watering pushes moisture down, and the roots follow it. That's what makes a lawn hold up through a hot, dry stretch.

The tuna can test

Before you touch the sprinkler timer, find out how much water each zone actually puts down. Every system is different.

1. Set out 4 to 6 empty tuna cans (or any short, straight-sided containers) across one zone.
2. Run that zone for 15 to 20 minutes, then check the cans.
3. Keep running and checking every 5 to 10 minutes until the cans average about 1 inch.
4. Write down how long it took. That's the time for one inch in that zone.

The next morning, push a soil probe in to see how deep the water went.

Test every zone. A sunny front yard with spray heads and a shady backyard with rotors can be completely different.

A starting schedule by season

This is the standard Turf Method schedule for a typical Gulf Coast front yard. Use your tuna can results to adjust the minutes for your zones, and cut back after a good rain.

Always follow any watering restrictions in your city or water district.

Why early morning?

Early morning gives you the least evaporation and lets the grass dry off as the sun comes up. Watering at night leaves the lawn wet for hours in warm, humid air, which is exactly what fungus like large patch and gray leaf spot need. Midafternoon watering loses a lot to evaporation before it reaches the roots.

Signs your lawn needs water

• Leaf blades fold or curl lengthwise.
• The lawn takes on a dull, bluish-gray color.
• Footprints stay pressed down instead of springing back.

If one section browns while the rest stays green, check that zone's sprinklers before anything else. A stuck valve or broken head is common. If the brown spot is in a hot, sunny area next to concrete and watering doesn't help, look into chinch bugs.

Common questions

How often should I water St. Augustine grass?

Usually 1 to 2 deep waterings a week in the growing season, adding up to about an inch including rain. In peak summer heat it may need up to 1½ inches. Water less as it cools, and little or none while dormant.

What is the best time to water St. Augustine?

Early morning, ideally between about 4 and 8 a.m. The grass dries quickly as the day warms, which limits fungus, and less water is lost to wind and evaporation.

How much water does new St. Augustine sod need?

Much more often at first: keep the soil under new sod moist every day for the first couple of weeks, then taper to deep, less frequent watering as it roots. See new sod care.