How Often Should You Mow Your Lawn in Summer?

Your lawn doesn't grow at the same speed all year. In May, it's putting on height so fast you could almost watch it happen. By mid-July, that same grass might sit at the same height for two weeks straight. But a lot of homeowners around Edwardsville and Glen Carbon keep mowing on the exact same schedule from April through September, and that causes more problems than it solves.

Mowing too often in summer stress-burns grass that's already struggling with heat. Mowing too rarely in spring lets it get leggy and weak. The trick is adjusting your frequency to match what the grass is actually doing, not what your calendar says.

Spring Growth Is a Different Animal

Cool-season grasses — tall fescue, Kentucky bluegrass, perennial ryegrass — hit their peak growth in spring. Here in USDA zone 6b, that window typically runs from mid-April through the end of May, once nighttime temperatures stay consistently above 50°F. During that stretch, your lawn can grow an inch or more per week.

That means mowing every five days isn't unusual in May. Some weeks, especially after a warm rain, you might even need to cut it twice. If you wait a full seven days during peak spring growth, you'll end up removing too much of the blade at once, which shocks the grass and leaves behind brown clippings that smother the turf underneath.

By early June, growth starts to taper. You can stretch to a weekly cut. And once the real heat arrives — usually around the second or third week of June in the Metro East — the schedule shifts again.

The One-Third Rule Matters More When It's Hot

You've probably heard the one-third rule: never remove more than one-third of the grass blade in a single mowing. It sounds like one of those guidelines people mention and then ignore. But it actually matters, and it matters more in summer than any other time of year.

When you scalp a lawn in spring, it bounces back in a week. Cool temps, plenty of moisture, active root growth — the grass recovers fast. Cut too much off in July and you're removing the part of the plant that shades the soil, holds moisture, and feeds the roots through photosynthesis. The grass can't recover quickly because it's already spending most of its energy just staying alive in the heat. So what looks like a normal mowing job can set your lawn back for weeks.

If your mowing height is 3.5 inches, that means you should be cutting when the grass reaches about 5 inches. In peak summer, that might take 10 days instead of 7. Sometimes longer.

Raise Your Mowing Height in Summer

This is one of the simplest things you can do for your lawn, and most people skip it. Raise your mower deck by at least one inch when summer arrives. If you've been mowing at 3 inches in spring, bump it to 3.5 or even 4 inches for June through August.

Taller grass does a few things that shorter grass can't.

First, it shades the soil. That keeps soil temperatures lower, which means the root zone stays cooler and retains moisture longer between waterings. Second, taller blades have more surface area for photosynthesis, which means the plant can produce more food for itself during a period when it's under stress. Third, taller grass crowds out weeds. Crabgrass seed needs sunlight to germinate. A thick canopy at 3.5 or 4 inches blocks that light from reaching the soil surface. University of Illinois Extension research backs this up — raising mowing height is one of the most effective weed-prevention strategies for cool-season turf.

I've seen lawns in Troy and Maryville that stay green well into August purely because the homeowner keeps the deck high. Their neighbor across the street, cutting at 2.5 inches, has a brown, thin lawn full of crabgrass by the Fourth of July.

When to Skip Mowing Entirely

There are days you should not mow at all. And weeks where the best thing you can do for your lawn is leave it alone.

If daytime temperatures are above 90°F, mowing adds stress to grass that's already at its limit. The act of cutting creates open wounds on each blade, and those wounds lose moisture fast in extreme heat. If you can, push the mow to early morning or wait for a cooler day. During heat waves — those stretches of 95°F-plus days we sometimes get in mid-July — it's better to skip entirely.

Don't mow when the lawn is wet, either. Wet grass clumps, which smothers the turf below. The mower tears the blades instead of cutting them cleanly, leaving ragged tips that brown out and invite disease. And wet soil compacts under the weight of the mower, which makes everything worse over time.

Then there's dormancy. Cool-season grasses like fescue and bluegrass will go dormant during extended hot, dry periods. The lawn turns brown, but it's not dead — it's conserving energy. (If the brown areas look patchy rather than uniform, you might be dealing with something else entirely — here's how to tell the difference.) A healthy, established lawn can survive four to six weeks of dormancy without permanent damage. Mowing a dormant lawn does nothing productive. The grass isn't growing. All you're doing is grinding down the remaining leaf tissue and exposing the crown of the plant to more sun and heat.

If your lawn has gone dormant, leave it alone until it greens back up after a good rain or cooler temperatures return.

What This Looks Like in Metro East Illinois

So what does a realistic mowing schedule look like for someone in Edwardsville, Collinsville, or Bethalto? Here's roughly how it breaks down by time of year, assuming you're growing tall fescue or a fescue-bluegrass mix, which covers most residential lawns in this part of Illinois.

Mid-April through May: Mow every 5 to 6 days. Growth is fast. This is the time you'll be out there the most. Keep the deck at 3 to 3.5 inches.

June: Transition to every 7 days. Raise the deck to 3.5 or 4 inches. Growth slows as temperatures climb, but there's usually still enough rain to keep things moving.

July and August: Every 7 to 10 days, sometimes longer. During dry spells with temps above 90°F, stretch to every 10 to 14 days. Watch the lawn, not the calendar. If the grass hasn't grown since your last cut, don't cut it again just because it's Saturday.

September: Growth picks back up as temperatures cool and fall rains arrive. Return to every 5 to 7 days. This is also when aeration and overseeding become worth doing, since the grass is actively growing again.

One thing that catches people off guard is how much the schedule varies year to year. A wet, cool June means you're still mowing weekly. A hot, dry June means you might only mow three times the entire month. The weather around here doesn't follow a script, and your mowing schedule shouldn't either.

A Quick Cheat Sheet

• Spring peak (May): every 5 days, 3 to 3.5 inch height
• Early summer (June): every 7 days, 3.5 to 4 inch height
• Mid-summer (July–August): every 7 to 14 days depending on heat and rain
• Fall recovery (September): every 5 to 7 days, back to 3 to 3.5 inches

And always: sharpen your blades. A dull mower tears grass instead of cutting it, which makes every mow more damaging than it needs to be. Torn blades dry out at the tips, giving the lawn a white or brown haze a day after mowing — which people sometimes mistake for disease. You should be sharpening or replacing blades at least twice per season, or more if you're hitting a quarter-acre-plus every week.

One more thing people forget: clippings. If you're mowing at the right frequency and following the one-third rule, you can leave the clippings on the lawn. They break down quickly and return nitrogen to the soil. But if you've let the grass get too tall and you're cutting off a lot at once, bag those clippings. Heavy clumps left on the surface block sunlight and trap moisture, which can encourage fungal problems during humid stretches in June and July. It's a small detail, but it adds up over a full season.

Don't Want to Think About It?

If tracking growth rates and adjusting mowing height sounds like more than you signed up for, that's fair. It's one of those things that's simple once you know the patterns, but it takes a season or two of paying attention before it becomes second nature. And honestly, some weeks it's hard to tell whether the grass has grown enough to justify pulling out the mower. You end up standing in the yard squinting at the grass like that's going to help.

We handle weekly and bi-weekly mowing for homes across Edwardsville, Glen Carbon, Troy, Maryville, and the surrounding areas. We adjust the schedule and deck height throughout the season based on what the grass actually needs, not just what's on the calendar. If you want to hand it off, give Erik a call at (314) 494-1136 and we'll get you set up.