how to safely mow a steep hillside

How to Safely Mow a Steep Hillside

In Lawn & Garden by Jamie

While we all wish our lawns were perfectly flat, if only to make mowing easier, most of us have to deal with mounds, slopes, and even steep hillsides. And mowing slopes is dangerous work. How can you mow steep hillsides safely? What mowers are safer? And what can you do instead?

To safely mow a steep hillside, assess the hill and find hidden hazards and drop offs. Use a push mower horizontally along the slope and set the mower deck high. Wear shoes with traction and never mow wet grass. If you can’t mow safely, replace grass with no-mow alternatives, meadowscape, or turn into terraced gardens.

Can a Hill Be Too Steep to Mow?

Yes, a hill can be too steep to mow. The steeper the hill, the more dangerous it becomes to mow. A hill that’s steeper than 22 degrees can only be mowed safely with a push mower, but as the steepness increases, it’ll become more and more difficult. Your common sense is the overriding factor. If you feel like the mower is wobbling too much, has lots of hidden pits or drop offs, or you don’t feel safe mowing it, then it’s too steep.

If the hill’s too steep to mow safely, consider replanting with meadow grass and flowers (no mowing, erosion-control) or turn the hill into terraced gardens or lawn. If your yard is just one steep slope, a terraced garden can excellently use otherwise unusable space, and you can make a terrace or two into lawn you can actually enjoy.

How Steep of a Slope Can You Mow?

The steepness of the slope that you can mow depends on the type of mower that you’re using. A riding or zero turn mower can be used (with precautions!) on a slope up to 15 degrees. A push mower can be used on a slope up to or above 22 degrees, depending on how safe the slope is.

What Kind of Mower Should I Use on a Hill?

It’s really important to use the right mower when mowing a hill. Riding mowers are incredibly dangerous because they’re off-balance and likely to roll over, with you underneath it. Instead, use a push mower, whether a reel or rotary mower. A battery-powered or push reel mower with a small deck is best as it’ll be a lot lighter and easier to maneuver.

Before buying a new mower or using your current mower, check the manual to see what’s the maximum slope grade that the mower can function safely on. Manufacturers test this stuff.

According to the Occupational Safety & Health Administration (OSHA), you can generally use:

  • Riding mowers or tractor mowers on a slope of 0 to 15 degrees
  • Tractor mowers on a slope of 15 to 22 degrees
  • String trimmers, push mowers, or specialized equipment on a slope of 22+ degrees
  • String trimmers and push mowers used within 5 feet of a drop-off.

But always use your common sense over any recommendations.


8 Tips for Mowing a Steep Hillside

#1 – Use common sense!

No amount of tip lists or manufacturing testing can replace common sense. Only you can see and assess the slope and feel how steady the lawnmower is. Before mowing, assess the slope for yourself. Mark any drop offs, hidden obstacles, and other hazards. If the manual says that your mower can handle this grade, but you feel the mower isn’t up to it, then don’t use it. No manicured lawn is worth injuring yourself over.

#2 – Assess the slope.

This goes along with common sense, but it’s so important that I want to include it twice. Walk over the slope. Look for any drop offs, bumps, holes, edges or drop-offs, and especially anything that’s hidden under the grass. If the slope edges a pond, keep your mower back (especially when using a riding or zero-turn mower). You don’t want any surprises.

#3 – Set the mower deck high.

A higher deck mower will make mowing a hill easier as the mower won’t bounce when going over bumps on the hill.

set mower deck higher

#4 – Go along (laterally) instead of straight up the slope and don’t change directions abruptly.

Pushing a mower straight up (or straight down) a slope is incredibly dangerous. If you slipped on the incline (grass is slippery! Grass cuttings are slippery! Slopes are slippery! Together, they’re incredibly slippery!), that mower will fall back toward you with the blades still running. Yikes!

Likewise, abrupt changes in direction can also spell disaster.

Instead, mow along the slope so that neither you nor the mower is below. That way, if you slip, at least the mower will not fall on you.

However, if you are using a riding mower on a slope less than 15 degrees (with Roll Over Protection System engaged!), mow vertically instead of side to side. A riding mower is more likely to slide and roll over when one side is higher than the other.

#5 – Use a push mower on steep slopes, and only use a riding or zero-turn mower on a gentle slope of less than 15 degrees.

Riding and zero-turn mowers are incredibly dangerous on hills steeper than 15 degrees. They’re always off balance because of the angle and they’re likely to roll over with you falling underneath. And even if you don’t roll underneath the riding mower (or on the exposed blades!), you can still break an arm or leg from the fall or get a concussion. In 2007, there were 61 deaths and 15,000 injuries while using zero-turn mowers. Don’t become a statistic.

If you use a riding mower or zero-turn mower on a 0 to 15-degree slope, then make sure you:

  • Only mow completely dry grass so the mower can maintain traction,
  • Drive at a steady and consistent pace,
  • Avoid sharp turns or turns and adjustments at high speeds, and
  • Engage the Roll Over Protection System (ROPS) to prevent rollovers.

If the slope is steeper, use a push mower. A mower with a small deck will be lighter and easier to handle. Check the manual to see what the maximum slope grade a mower can handle. (Manufacturers know this stuff!)

#6 – Wear cleats for traction.

Wear shoes with the best possible traction you have, or best yet, get a pair of cleats. This is not the time for the sneakers you’ve worn around so much the sole is completely smooth.

#7 – Never mow a hill when the grass is wet.

Do you want to know what’s more slippery than grass on a slope? Wet grass on a slope! And while an electric mower is a better choice on slopes than a gas-powered one, it’s also more dangerous on wet grass. Electricity and water do not mix.

mowing wet grass

And if your life and safety weren’t enough inducement to stay away, then mowing wet grass is also a hundred times more difficult as wet grass clippings gum up the blades, and the grass is going to look terrible. Absolutely terrible.

If your local climate is rain, rain, rain, and you’re wondering exactly when you’re supposed to mow your hillside grass, then consider no-mow alternatives.

#8 – Consider no-mow alternatives.

Mowing a hill is never completely safe. If your hill is too steep for you to mow safely, or you only have a riding mower, or even if you just dread having to lug a mower all over a hill, then consider replacing the grass with something else.

No-mow alternatives include:


Hillside Mowing FAQs

Can you cut grass on a steep hill with a riding lawn mower?

No, you definitely should not cut grass on a steep hill with a riding lawn mower. As the riding mower is severely unbalanced on a slope, it’s likely to roll over — and you with it. Only use a riding mower on a hill that’s under 15 degrees slope and with dry grass. Mow at a steady pace with no sharp turns or high-speed turns or adjustments, and use rollover protection systems.

If you can, buy a push lawn mower that can be used safely on a hill, or replant with meadow grass that doesn’t need to be mowed.

Can you mow a steep hill with a zero-turn mower?

If a hill is steeper than 15 degrees, then do not mow it with a zero-turn mower, even in the most ideal conditions and with rollover protection system (ROPS). On slopes less steep than 15 degrees, make sure the grass is dry, mow at a consistent pace while slowing down for turns and adjustments, wear a seatbelt, and deploy the rollover protection system (ROPS) to protect against rolling over.

How do you measure the steepness of a hill?

You can measure the steepness of a hill either by slope or by degree. To calculate these, you need two numbers: the rise (the vertical distance between the top and the bottom) and the run (the horizontal distance between the start of the hill and the top).

You will need:

  • 2 wooden stakes
  • a piece of cord or twine
  • a level (one that hangs from the rope is helpful)

slope of a lawn calculated grading

To measure the slope:

  1. Drive the first stake into the top of a consistent slope. (As much as we’d love for slopes to be even, often they will have different angles at different points. So try to find a place that has a 100 inches that’s relatively consistent.)
  2. Tie the rope to the bottom of the first stake.
  3. Measure out 100 inches of rope. (This 100 inches will be the run, so the 100 inches mark in the next step needs to be level/flat, not at the same angle as the hill.)
  4. Using the level on the rope, place the second stake at the 100 inches mark. Keep the rope level with the knot on the first stake, not at the same angle as the slope.
  5. Tie the rope as it’s still level with the knot on the first stake (and double check with the level!).
  6. Along the second stake, measure the height from the stake’s bottom to the new knot. This number is your rise.
  7. Divide the rise by the run (Slope = Rise / Run) and multiply by 100 to get the percent.

To get the degree angle, you can either use the same rise and run numbers in an online calculator or you can use the slope percentage to look up the degree angle.