Here’s How Long Grass Grows If You Don’t Mow Your Lawn (And Why You Really Need To)
Your grass can only grow so long—but mowing an overgrown yard is always a tall order
Highlights
Most turf grasses can grow up to 4–24 inches tall.
An overgrown lawn is more susceptible to pests, weeds, and diseases.
If you don’t mow your lawn, it may be difficult to mow it in the future.
You can only cut one-third of the height of your overgrown grass at a time.
If your grass grows too tall, spread mowing out over a week.
Have you ever looked at your lawn with the unshakable feeling that you don’t want to do more yard work and thought to yourself, “How long could it possibly get?” We’ve all been there.
Skipping the odd mow isn’t going to let your grass run wild, but it’s not a good idea to let it endlessly grow either. How long grass grows depends on the type. Here’s what you need to know.
How Long Grass Grows by Type
Though ornamental grass and prairie grass heights tend to vary, the most common turfgrasses can actually only grow between 4 to 24 inches. Bunchgrasses, like tall fescue, tend to grow outward rather than up, which can make them look shorter. Here are some common lawn grasses and their mature heights (keep in mind, you may have a mix of grasses in your yard):
| Type of Grass | How Tall It Can Grow |
|---|---|
| Buffalo grass | 8 – 10 inches |
| Bermuda grass | 4 – 12 inches |
| Tall fescue | 4 – 12 inches |
| Zoysia grass | 6 – 12 inches |
| St. Augustine grass | 6 – 12 inches |
| Fine fescue | 8 – 12 inches |
| Perennial ryegrass | 12 – 24 inches |
| Kentucky bluegrass | 18 – 24 inches |
What Happens If You Don’t Mow Your Lawn?
The short answer is that, after a few months, your lawn will look uneven—but the long answer is, well, long.
Grass doesn’t grow straight up indefinitely. At a certain point, it can’t support its own weight and bends over. This is common with ornamental grasses (and a sign they need a trim). Typically, grass has to reach 18 to 24 inches of height before this happens.
You’ll notice the most drastic changes in your lawn after about a year of neglect. At this point, invasive species—like weeds, clovers, crabgrass, and wildflowers—will start to take over. Insects and other gritters could move in, and eventually, your lawn won’t look like your lawn at all. Of course, most homeowners aren’t abandoning their properties. They’re just skipping the occasional lawn maintenance, so it won’t ever get to this point.
The Problem With Tall Grass
The average cost for a pro to mow a lawn is only $130, so if your grass is really tall, it’s probably worth it to hire a professional grass-cutting service near you and save yourself the headache. Though most of us aren’t letting our backyards become part of the wilderness, tall grass does actually cause practical problems.
1. It’s Hard to Mow
Once your grass grows more than a few inches, it becomes more difficult to mow. You can’t just lop off a few inches without damaging the blades. Instead, you’ll need to cut it down little by little every day until it’s the desired height.
Beyond that, grass clippings tend to pile up and sit on top of the lawn, which blocks the sun and can damage the grass below. You’ll have to remove the clumps—and suddenly what should’ve been a simple mow is now a week-long process with multiple steps.
2. Tall Grass Could Damage Your Mower
Sometimes grass isn’t just hard to mow—it’s too long to mow entirely. Tall blades can clog your lawn mower and cause it to overheat. If your lawn is particularly long, you may have to first go in with a grass trimmer (also known as weed whacker) or a more powerful bush hog mower.
3. The Health of Your Lawn Suffers
Cutting your grass actually promotes healthy root growth which, in turn, leads to a healthy lawn. The longer your grass goes without a trim, the weaker and more damaged it can get, which leaves it vulnerable to pests, disease, and weeds.
4. You Could Get a Fine
Some areas—particularly areas with homeowner’s associations—have rules about how long grass is allowed to grow. If your grass exceeds the maximum length, you’ll get a fine (which could be as much as a few hundred bucks).
What Is the Best Height for Your Grass?
The right height for grass depends on the type of grass you have. Keeping your grass long leads to an unhealthy lawn, but so does mowing too low. The ideal height for most turf grasses is between 2 to 3 inches. Some warm-season grasses like Bermuda grass and zoysia grass should be kept at a height of 1.5 to two inches.
How to Cut Overgrown Grass
If you want to mow your lawn like a pro, you have to tread carefully with overgrown grass. Always observe the rule of thirds and never cut more than one-third of the height of the grass at a time. If your grass is too tall, you’ll need to spread your mowing out over a couple of days. To cut tall grass:
Measure your grass with a yardstick
Set your mower height to remove one-third of the length
Mow your lawn
Wait a couple of days
Re-adjust your mower to cut another third
Repeat the process until your grass is around 2 to 3 inches in height. When you’re done, rake the clippings (they won’t decompose as easily as normal clippings). If your grass seems too long to mow with your mower, start with a weed wacker, rent a bush mower, or make things easy by hiring a local lawn care service.