Mowing Slopes Safely – Let’s Get Real About Hills.

Updated March 2018.  I read many reviews complaining about lawn tractors not being able to mow on a hill. “They don’t have enough traction.” “I have to use tire chains.” “I have some fairly steep hills on the property and the tractor stands so tall that it is not safe at all on hills over 15 degrees. So I couldn’t mow half of my lawn.”

It’s time to stop complaining and get real. You will not be able to mow all of your lawn with a lawn tractor or zero-turn if there are slopes.

The truth: Residential Lawn Tractors and Zero-Turns are not designed to mow on slopes steeper than 15 degrees.  They all tell you that in the manual. There are mowers designed to mow hills but the cheapest one on the market is over $10,000. The good ones are in the $20,000 to $50,000 range.

If it is too steep to mow, turn it into a landscape bed or wildlife area.

Be Safe:

• On steep slopes, GO SLOW.
• Sidehill mowing, watch the front uphill tire to verify it’s making a solid depression in the grass. If it isn’t, SLOWLY turn downhill.
• Always have an escape route when mowing or traveling over rough ground so if the machine kicks out of gear or the brakes fail or both you can steer to safety.
• Keep the brakes properly adjusted and maintained.
• Be very, very aware that going up a steep slope how quickly and easily a tractor will flip back on you. If the front end does come up, the rear wheels provide the motive force to flip it back.
• Generally speaking, brakes are for stopping, NOT slowing down in tractor usage, that’s what the trans is for. If you step on the left pedal you set the parking brake and the rear wheels will lock. In most cases this will not hold you on the hill, instead, you will slide down the hill.
• The “GO SLOW” mentioned above means regulate your speed with the transmission.  Choose a lower or lowest gear, with a hydro, do the same, keep the RPM’s (engine speed) up.

Zero-Turns are not weighted to mow up a hill. Especially older zero-turn mowers. They will tip over backward.

• If you cannot back up the slope or if you feel uneasy on it, do not mow it with a ride-on machine.
• Mow up and down slopes with a lawn tractor, not across.
• Watch for holes, ruts, bumps, rocks or other hidden objects. Uneven terrain could overturn the machine.
• Choose a low ground speed so you will not have to stop or shift while on a slope.
• Do not mow on wet or damp grass. Tires may lose traction.
• Do not mow on drought-dry grass. Tires will lose traction.
• Always keep the machine in gear when going down slopes. Do not shift to neutral and coast downhill.
• Avoid starting, stopping or turning on a slope.
• Keep all movement on slopes slow and gradual.
• Use extra care while operating the machine with grass catchers or other attachments; they affect the stability of the machine. Do not use them on steep slopes.
• Do not try to stabilize the machine by putting your foot on the ground.
• Do not mow near drop-offs, ditches or embankments.

46 inch 2 blade decks on lawn tractors do not have the clearance between the rear of the deck and the rear tires to install tire chains.

If you have a Walk Out Basement the angle is too steep to mow side to side or up the hill. Mow down the hill, drive around to the top of the slope and mow down. Yes, you may have to drive around the house a dozen times to do this, but it is the only way. Never attempt to mow or drive up the hill

Don’t even consider using a rear mounted bagger on hills. On both tractors and zero-turns that makes them too heavy in the rear.

Don’t even consider a leaf/lawn vac on slopes. The transmissions in lawn tractors are not heavy enough and you will destroy the trans. On garden tractor, there may be too much weight on the rear hitch. Blow the leaves to the bottom of the hill with a handheld blower or backpack blower, then pick them up with your vac.

Do not mow near drop-offs, ditches or embankments. Don’t mow near a pond. The first 6 to 10 feet of turf by the water’s edge is water-logged and your mower will sink in and tip over.

Follow the rules in your operator’s manual. But remember, an unseen hole on the down-slope or a bump or stick of wood on the uphill side can increase your slope quickly and cause an accident.

 Seatbelts and ROPs won’t save you if there is water

What is available today For the Homeowner:

There are very few residential mowers specifically designed to mow slopes. Here are a few that work:

Acrease Wing and Rough-Cut Mowers: Acrease Mowers are able to mow slopes. They use full pressure engines on the commercial models that won’t blow up on slopes greater than 15 degrees. Be aware these mowers are heavy and you will need a heavy tractor to pull them. I actually used 2 in tandem to mow a 10-foot road ditch (Swisher T-60 Trailmower 14.5hp. is only designed for 15-degree slopes. The engines are splash lubricated and will blow up on slopes greater than 15 degrees.)

Craftsman 4WD walk-behind.

Husqvarna:

Walk-Behind Husqvarna HU800AWD All Wheel Drive

There are a few tractors with a rear differential lock from Craftsman Pro, Cub Cadet and Husqvarna that give you better traction going up and down slopes, but they are still only rated for 15 degrees.

There are other mowers that will handle slopes but all of them are commercially rated.  Standon Mowers, 60 inches and larger like the Wright Stander are capable of mowing greater than 15 degrees. Toro Walk-Behind commercial mowers with the T-Bar steering also work well. Of course, there are the dedicated slope mowers like the KutKwick and the new robotic mowers.

Final Thoughts

Many people don’t read the operator’s manual or feel these warning statements are “just guidelines.” Even staying under 15 degrees there are still ways to tip your lawn tractor or zero-turn mower over. Mowing commercially for many years I have had too many close calls and I still use my “Pucker-meter” all the time.  The seat of your pants is the best gauge – really. It is a long, slow, careful learning experience. You have to get to know your machine and how to best approach various terrain. Going slow and low is always good.

If is feels wrong, if the hill feels too steep, if the tractor doesn’t feel right, I don’t mow it.

(This Last From Consumer Reports)

What we tested, what we found. We compared several zero-turn-radius riding mowers marketed to consumers with a lawn tractor on slopes ranging from roughly 5 to 20 degrees. We used a typical 4.5 mph mowing speed over both dry and wet grass, going up and down as you should with most ride-on machines. So far, so good.

The trouble began when we made a hard turn down 10- to 15-degree slopes. The zero-turn riders lost most of their steering control, skidding straight into our simulated hazards. All could stop in time when the brake was applied, though stopping entails manipulating two levers that also do the steering. That’s less intuitive than a tractor’s foot brake. And while the zero-turn models steered controllably at slower speeds, time savings is a major selling point for zero-turn machines.

The rollover risk

  Rollovers are another concern with all ride-on mowers, contributing to the more than 15,000 injuries and 61 deaths associated with those machines for 2007, according to estimates based on CPSC data. Commercial tractors and riding mowers often include a roll bar, called a rollover protective structure (ROPS), and a safety belt. Both are supposed to work together to protect and confine the operator if there’s a rollover. But even that approach leaves lots of room for error.

• Choose a front-steering tractor over a zero-turn-radius rider if you’re mowing slopes 10 to 15 degrees or greater. (A 10-degree slope rises roughly 20 inches over every 10 feet.) If you already own a zero-turn-radius riding mower, be sure to mow slowly on hills. And mow only on dry grass to maximize traction.
• Give yourself time to learn the controls on any ride-on mower, especially a zero-turn mower’s levers for steering and speed.
• Mow straight up and down slopes with a tractor or rider unless the manual says otherwise. And mow side-to-side with walk-behind mowers, start at the bottom and work up-hill. Always turn uphill.