The Best Way to Mow a Hill

Slope mowing presents a challenge to property owners and landscaping professionals alike.  There are many risks involved that can result in operator injury, equipment damage or both.  Safe slope-mowing begins with selecting the correct mower for the task.

Walk-behind and ride-on mowers should be equipped with safety features that disengage the blade and lock the wheels in case you slip while mowing.  If your machine does not have these features, do not use it to mow slopes.  There is no need to risk injury.

The first step when mowing slopes is to determine and stay within the equipment’s safety zone.  Most lawnmower manuals stipulate that anything over 15 degrees should not be mowed, but it isn’t easy to determine the slope of a hill by eye. Below are few rules of thumb that will increase operator safety when mowing hills or slopes.

Walk-Behind Mowers

Walk-behind mowers are often the best piece of equipment for mowing hills.  Unlike ride-on mowers, they present little risk of toppling.  Self-propelled walk-behind mowers are easier to operate and therefore increase work rates.

Operators may require specialized equipment for hills and slopes that are only maintained a few times per year.  Standard walk-behind mowers will overheat and risk engine damage in growth over a foot high, while high-grass and brush mowers like the AS 901 Flail Mower are specifically designed for this terrain.

These specialized mowers are engineered to mow high grass on slopes and have a low center of gravity, special agricultural tires, additional oil and fuel pumps and locking differentials for increased safety and performance.   Standard walk-behind mowers lack these features and are thus unsafe starting at 20 degrees of incline.  The machine will swerve downhill and the engine will struggle to keep lubricated the steeper you go.  Ultimately, it is not worth putting the operator and equipment at risk of damage or injury.

Ride-On Mowers

Ride-on mowers provide increased comfort and convenience— however, it is extremely important to make sure that your ride-on mower is engineered for the task at hand.  Standard ride-on mowers are designed for safe operation only on gentle inclines up to a maximum of 15-degrees.  Zero-turn mowers are not suitable for slopes, and can become especially dangerous past 15-degrees if the grass is wet.

A good way to test if a hill is too steep for a ride-on mower is by reversing up the slope.  If the machine loses traction, it is not suitable for the task.  Moreover, slope mowing on ride-on machines must be done in rows up-and-down the hill.  Mowing side-to-side can result in the mower tipping over.

When mowing hills over 15-degrees and/or difficult terrain, specialized equipment like the AS Sherpa 940 4WD XL and the AS 940 Sherpa RC can get the job done safely and efficiently.  The only alternative is to clear these areas with weed whackers which is a time-consuming process that, at best, yields uneven results.  Investing in the proper equipment not only saves time and money in the long term, but greatly improves operator safety.

Proper Mowing Conditions

Mowing should be done in dry weather during peak daylight hours.  The slope should not be in the shade as rocks and other obstructions may be more difficult to see.

Before turning on the machine, inspect the hill you wish to mow in order to locate obstructions and remember that hill mowing is always done side-to-side when using a walk-behind mower, and up-and-down the hill when using a ride-on mower.

Tips for mowing on slopes:

  • Mow side-to-side with walk-behind mowers, not up and down
  • When mowing a hill side-to-side, verify that the front uphill tire is making a solid impression in the grass. If it isn’t, slowly turn downhill
  • Mow up-and-down slopes with a ride-on mowers, not across
  • If you cannot back up the slope or if you feel uneasy on it, do not mow it with a ride-on machine
  • Do not operate mowers on slopes that exceed the limits specified by the operating manual
  • If instructions are not available, evaluate the terrain and slope conditions and err on the side of caution to ensure operational safety
  • Use a slope indicator, also known as a clinometer or inclinometer
  • Don’t leave workers unsupervised in potentially dangerous conditions
  • Regulate your speed with the transmission on slopes.  Choose a lower gear and keep the rpm’s (engine speed) up
  • Always have an escape route when on rough ground. This way if the machine kicks out of gear or the brakes fail, you can steer to safety.  4WD machines with hydrostatic drives are safest
  • Watch for holes, ruts, bumps, rocks or other hidden objects. Uneven terrain can overturn the machine
  • Do not mow on wet or damp grass. Tires may 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

We hope this information is useful!  The most important guidance when operating mowing equipment is to take safety seriously.  This involves evaluating the terrain for the correct equipment, and, whenever in doubt, to err on the side of caution.