In a large swath of the country, the coming of fall and winter means that annual chores need to get done before the weather turns bitter. Storm windows are put up, snow tires are put on, outdoor furniture is covered or put away.

As a landscape contractor, you, too, have a checklist of tasks that must be accomplished before the weather turns frigid. Every company that owns commercial mowers has its own set of best practices when it comes time to put its fleet to bed for the winter.

Of course, some mowers don’t get to hibernate for the winter. Those are the units with attachments that allow them to be converted to snow blowers. But they still need some special tweaks for winter, too.

The colder and wetter it gets where you live, the more important it is that winter prep be done properly; these machines are your livelihood, and as you know, they don’t come cheap.

We asked several contractors who do business in some of our most snowy states what they do to prepare for winter. We also talked to some equipment manufacturers and a repair shop to see what they recommend. Some of their answers may surprise you.

Winter comes quickly in these places. “Here in northern Michigan, we can go from leaf cleanup to falling snow within one week,” said Drew Stanfuss, owner of Greenscape Lawns, LLC, in Whitehall.

Tim Senkbeil, fleet manager at Kujawa Enterprises, Inc. (KEI) in Oak Creek, Wisconsin, knows all about that. “It’s pretty chaotic. It can be difficult to get everything done in the short period of time that Mother Nature gives you.”

Flush that fuel?

There are different schools of thought on what to do about the fuel left in the tank following the last mow of the season. (This applies only to mowers that use straight gas, not to diesel or propane-powered units). It has to do with the ethanol that’s blended into our gasoline. Most gas today contains ten percent ethanol, and there’s a push to go up to 15 percent.

“What everyone needs to understand is that the ethanol levels in the fuel we’re buying today is not good for small engines, carburetors, gaskets and hoses,” says Brice Hill, associate product manager at Coatesville, Indiana-based Dixie Chopper.

What’s wrong with ethanol? It attracts water. And water in a gas tank is never good news.

“There are two camps,” says Bruce Tallman, technical services manager at Walker Manufacturing in Fort Collins, Colorado. “One says, ‘Drain out all the fuel.’ Another says, ‘Fill them up so you won’t get condensation, add stabilizer, and let the engine run a bit so it mixes with the fuel. Make sure you leave a little air space for expansion.’ We land in that camp.”

Joe Markell, owner of Sterling, Virginia-based Sunrise Landscape and Design, Inc., uses both techniques. “We’ll either drain all the fuel out, or fill them up and throw in some stabilizer.”

Turner Anderson, internet marketing manager at Jack’s Small Engines, LLC, Jarrodsville, Maryland, belongs to the drain-it-all-out school, believing that not doing so is “practically a death sentence for a mower’s fuel system. You’ll want to remove any fuel that’s going to be sitting in there for 90 days or more.”

Senkbeil is another drain-it-all-out guy. Once KEI’s mowers are turned in for the winter, he runs all of them until they’re out of gas. “Reformulated (ethanol-infused) gas can be a pain sometimes; it doesn’t keep for very long, only about three months. After that, it’ll varnish, and gum up the smaller workings of the engines, particularly the carburetors.”

Even if a mower is run until it stalls out, there can still be an ounce or two of fuel left in the bottom of the carburetor bowl. That’s enough to cause trouble, according to Anderson. “There can still be a whole bunch of varnishing, or gummy deposits, from the alcohol dissolving the metal. Once you start the mower up in the spring, you’re pushing all that gunk into those tiny carburetor jets, and it clogs them up. Now you’ve got a dead carburetor, all because you didn’t drain out that little fuel bowl.”

If you’re going to fill your mowers, check to see if they have ventilated gas caps. “I’ve actually witnessed this, where all the gas evaporated out through the cap, and all that was left was stabilizer,” said Senkbeil. “That still gummed things up.”

Finally, Anderson warns that no lawn mower manufacturer’s warranty will ever cover a fuel-related issue. Keep that in mind as you decide what to do.

Clean those decks

Tom Person, service technician at Beatrice, Nebraska-based Exmark advises you to clear any debris from the decks before you stow your mowers. “Moisture in grass is incredibly abrasive and corrosive. What we don’t want is for that darned wet grass to sit on that steel, anywhere. It’s going to cause rust.”

It’s bad enough to have soggy mud and grass hanging around, but then there’s fertilizer. Nitrogen, specifically, is incredibly corrosive. Throw a little moisture in with that, and you’ve got a pretty good recipe for pitted metal.

Senkbeil says that, ideally, the cleaning of decks and other surfaces is done by the mowers’ operators before the units get stored. However, “in the real world” this doesn’t always get done.

Person wants you to clean your decks, but preferably not with a pressure washer; he says that’s the biggest mistake commercial mower owners make, as it can drive water up into the bearings.

“Now you’ve got water up in a cavity, and you’re going to let it sit all winter long, and freeze? Not a good idea.” He suggests scraping out decks with a putty knife instead, then blowing off the debris with an air hose.

However, as Senkbeil pointed out, there’s the ideal world, and then there’s reality. Contractors are going to pressure-wash their mowers; it’s the fastest way to get it done. “If you have to use water,” suggests Person, “run the engine for fifteen minutes out on the concrete, with the deck engaged, to warm up those bearings. Then hit it with the air hose to dry the rest of it out.” So, if you’re going to give those decks a ‘wash and set,’ just make sure you blow-dry them when you’re done.

You can also pump some lube into the bearings; that’ll push the moisture out too.

Batteries: disconnect or not?

This is another area where people differ. Some prefer to disconnect batteries entirely; others like to leave them hooked up to trickle chargers.

“Minimally, you should disconnect the cables from the batteries,” advises Sean Dwyer, director of regional product development for Husqvarna, USA, in Charlotte, North Carolina. He says this because commercial mowers increasingly incorporate extra gauges, hour meters and so forth, that convey information about a unit’s internal functioning.

All those little indicators can be parasitic loads on a battery, drawing power even when a mower is off. Anyone who’s ever tried to start their car after leaving the dome light on all night knows what he’s talking about.

“In the far North, you pretty much have to leave a battery on a trickle charger,” says Anderson. “Otherwise, it’ll be as dead as a doornail in the spring.” Stanfuss disagrees. “We’ve never had a problem with batteries, never had any freeze or go dead. We just leave them right in the mowers, all hooked up and everything. They go in a spot in our shed that’s not heated or anything, where we stow all the off-season equipment.”

Senkbeil says he usually gets two or three years out of a battery, depending on its size and the style of the machine it’s in. At the end of the mowing season, he disconnects all the battery cables.

“We have too many mowers to trickle-charge them all,” he says, adding that he can’t imagine having to buy enough tricklers for more than 100 mowers—much less, paying the power bill. There are no electrical outlets in the storage trailers, anyway.

Tallman points out one drawback to using chargers. “Somebody will hook up a two-amp charger, and then forget about it for the winter. But if the power goes out at some point, they can come back to a dead battery.” So, if you do put your batteries on tricklers, come back and check them periodically to see that they’re still trickling.

To tune or not to tune?

Here’s another area where practices vary. Some contractors like to do a full tune-up and oil change on their machines before locking the shed for the winter. Others prefer to put it off until the next season begins.

Person says that fall is the best time to fix any oil or hydraulic leaks, or anything that’s worn out, so you’re not scrambling come spring.

Anderson favors changing the oil before waving goodbye for the winter. “If you don’t, then you have this old oil sitting in your oil tank and filter, with the metal shavings and all the other contaminants in there, just waiting for the spring.”

Standfuss prefers to fix anything major that’s broken in the fall. “We also get our blades sharpened or replaced, and set every mower up fresh, so they’re ready to rock and roll in the spring.” But he prefers not to do any oil changes until spring, as he feels that even fresh oil loses viscosity when it just sits there for months.

Tune-ups can also wait. “That has to do mainly with the time crunch at the end of the year,” he says. Another reason: “If you tune up a mower in the middle of winter, it won’t run right when it’s 90 degrees outside,” he contends. However, he says that’s mainly true of his older units, less of a concern with newer, fuel-injected models.

Senkbeil and his crews go over each of the company’s mowers as they’re turned in. “We thoroughly inspect the machines and replace worn bearings, change all of the oil and fluids, check the spark plugs, the tires—all that fun stuff.”

“Our policy is, if some part looks like it’s about to wear out, whether we think it could make it through next season or not, we might as well replace it now; that way we know it’ll be good for the entire mowing season next year.”

If you have diesel mowers, check to see that all your glow plugs are in good condition. One bad glow plug will prevent the engine from starting. The Grasshopper Company in Moundridge, Kansas, advises you to activate them for five to ten seconds only, and never preheat them for more than 20 seconds.

If you have the time, it makes good sense to get your mowers into shape now, rather than wait for spring, when the local repair shops are going to have their hands full. You’ll get quicker turnaround, and maybe even a better deal, as it’ll be the shops’ slow season, too. They might even be running specials.


Most contractors won’t have the luxury of tucking their mowers away in nice, snug, heated garages. Thankfully, you don’t really need to.

KEI shuts its mower fleet in storage trailers over the winter. Some old, seldom-used machines kept as backups get covered with tarps and left outside. “We try to keep the snow off them,” says Senkbeil, “because moisture getting into nooks and crannies doesn’t help anything. That and the road salt, of course.”

“We store ours in a watertight storage unit,” says Sarah Payton, property maintenance manager at Greenspace Landscaping in Bozeman, Montana. “Because the snowpack comes up higher than the doorway, it can’t seep through the base. No animals can get in there, either; it’s pretty safe and dry.”

Animals? Yes, they can be a problem, especially if you have to store outdoors.

“Definitely cover those units tight,” says Anderson. “Whether you store indoors or out, because rodents are always a problem. Rats and mice, looking for warm places to hide, can burrow into your shed.”

“They’ll chew up anything rubber, then build nests with it, in your muffler exhaust, or up behind the air filter. Especially on larger units, there are lots of places for them to find homes, under the seats or decks. We’ve pulled quite a few mice out of engines.”

To keep critters out, he suggests getting mowers up off the ground, if possible. Seal them up good with elastic covers that’ll go around the wheels. Some contractors even use shrink-wrap. In any case, a $20 cover can keep you from having to replace fuel lines or starter cords.

Snow work winterization

If you’re using your mower for snow removal, Person says you may need to switch to a lighter weight oil, depending on your climate zone. "As the ambient temperature drops, the oil is going to be thicker and heavier, but the oil pump still has to be able to push it out. A thinner oil will pump easier."

The Grasshopper Company reminds you that different grades of fuel are used for warm and cold weather operation. They caution you to use a good quality, fresh winter-grade fuel, as summer-grade creates hard-starting situations in cold weather.

Also, according to a recent engineering bulletin from engine manufacturer Kubota, "use of biodiesel in a diesel engine in cold weather conditions can lead to fuel system plugging, hard starting and other possible unknown failures. Plugging can include both fuel filters and fuel lines."

We hope this information will help you sleep better in your warm winter pajamas, knowing that some of your most expensive rolling stock is safe, secure, and ready to go back to work as soon as that first robin sings.