How Often Should You Water Your Lawn in St. Louis? (The “It Depends” Guide)
It’s the most common summer question we hear from homeowners in Chesterfield, Wildwood, Ballwin, and across West St. Louis County:
“How long should I run my sprinklers?”
Your neighbor might say “20 minutes every day.” The internet says “1 inch per week.” But if you ask a turf professional who understands St. Louis heat, heavy clay soil, and unpredictable summer storms, the real answer is more strategic—especially when managing large commercial properties or shared HOA green spaces.
Watering incorrectly is one of the biggest reasons lawns fail in this region. Too little water creates weak roots. Too much — or watering at the wrong time — leads to fungus, disease, higher water bills, and inconsistent turf appearance.
Here’s how to do it the right way for St. Louis lawns.
The Golden Rule
If you take one thing from this guide, let it be this: Stop watering every day.
Daily, shallow watering keeps moisture near the surface, training roots to stay shallow. When July heat and Missouri humidity arrive, those shallow roots overheat and lawns collapse.
Instead, water deeply 2–3 times per week, just like a heavy summer rainstorm.
This pushes moisture 6+ inches into the soil, forcing roots to grow deep — where the soil stays cooler and moisture lasts longer.
Why St. Louis Soil Changes Everything
Most of Chesterfield and West County sits on heavy clay soil. Clay does not absorb water quickly — it repels it at first.
If sprinklers run for 40 minutes straight, much of that water runs off into streets, sidewalks, and storm drains instead of soaking in. This problem is magnified on large HOA commons, business campuses, and commercial landscapes.
The Strategy:
- Run zone for 15 minutes (Softens the hard clay crust).
- Wait 60 minutes (Allows the water to penetrate).
- Run the same zone another 15 minutes (Delivers deep hydration without runoff).
This prevents waste and gets water exactly where roots need it.
How Much Water Does Your Lawn Actually Need?
In general, St. Louis lawns need 1 to 1.5 inches of water per week, including rainfall. However, grass type and property use matter—especially for HOAs and businesses managing multiple turf zones.
Tall Fescue (Most Common in St. Louis)
Needs: ~1.5 inches per week in summer.
Risk: Heat sensitive. If it dries out completely in July, it often does not recover.
Zoysia (Popular in Chesterfield & Commercial Sites)
Needs: ~1 inch per week.
Benefit: Heat-tolerant. It can go dormant during drought and bounce back when watered.
Measure Your Water (The Tuna Can Test)
Don't guess—measure.
- Place 3–4 shallow cans (like tuna cans) around your lawn.
- Run sprinklers for 30 minutes.
- Measure the water inside.
The Math: If you collect ½ inch in 30 minutes, that zone needs 1 hour total per week to reach 1 inch.
Best Time to Water in St. Louis
The Window: 4:00 AM – 8:00 AM
Early morning watering lets moisture soak in before the sun evaporates it.
⚠️ Never water at night. St. Louis humidity + wet grass overnight = Fungus, Brown Patch, and Disease.
Put your lawn to bed dry!
Is Your Irrigation System Working Against You?
Broken heads, uneven spray patterns, and misaligned nozzles waste thousands of gallons and still leave dry spots. Furthermore, if you don't have a functioning Rain Sensor, you might be watering during a thunderstorm, which is money down the drain!
Dowco’s [Irrigation Maintenance Services] ensure every zone delivers the right amount of water exactly where your lawn needs it.
[Schedule your Chesterfield irrigation inspection today and make sure your system is summer-ready.]
