How to winterize a grill: gas, charcoal, pellet, griddle and pizza oven

Every manufacturer's winter list has the same shape. Get the grease and food out, because it feeds mice and mold and traps the moisture that starts corrosion. Get the steel dry and protected. Keep the fuel dry. Put a cover on. The details differ by fuel, and each type has one failure that does most of the damage over a winter: a nest in a gas burner, ash left in a charcoal bowl, damp pellets in a hopper, water pooled on a griddle plate, and a wet pizza stone.

One rule does not change. Weber's owner's manual says LP tanks must be stored outdoors, out of the reach of children, and never in a building, garage or any other enclosed space, and that storing the grill indoors is permissible only if the LP tank is disconnected and removed from it. Weber's storage blog repeats it in capitals: never store a propane tank indoors, and if the grill comes in, the tank stays outside. Blackstone's storage article gives the same instruction for a griddle's tank.

Gas grills

Weber's blog on preparing a grill for storage is built around three problems: critters, mold and corrosion. Mice treat an unused grill as a house with a roof and a food supply, so the inside has to be cleaned before it is put away, and more so if it stays outside. Mold feeds on leftover grease in the mild weeks of late fall and early spring. Grease and food residue trap moisture, which promotes corrosion and oxidation on the components.

Weber's checklist for a gas grill:

• Brush the grates, flavorizer bars and burners with a grill brush.
• Scrape every interior surface with a putty knife.
• Push the loose debris into the slide-out grease tray and the disposable drip pan, then empty the drip pan.
• Turn off the gas supply at the cylinder.
• If the grill stays outside, fit a cover to keep the exterior clean.
• If the grill comes inside, disconnect and remove the tank first and leave it outdoors.

The thing that ruins a gas grill over winter is what moves into the burners. Weber's manual explains that the combustion air openings on its burners carry stainless steel screens because spiders and other insects spin webs and build nests inside the venturi section, and its product care section has a procedure for cleaning those screens. What a nest does to the burner, and the symptoms to look for, are in the manual. Its spring instruction follows directly: after a period of storage or nonuse, the grill should be checked for gas leaks and burner obstructions before use, and the owner's manual is where that check lives.

The cylinder itself is simple. Weber says it is stored upright and secure, with the dust cap on the valve outlet whenever it is not in use, and its manual lists the other storage conditions. The propane tank run-time guide covers how far what is left in it will go in spring.

Charcoal grills

A kettle has no gas system to protect, so the whole job is the bowl. Weber's charcoal cleaning guidance: brush or scrape the built-up carbon off the underside of the lid, brush the cooking and charcoal grates, scrape the hard debris off the inside of the bowl, push the ash into the ash catcher, and empty the ash catcher. Weber's storage blog adds the same critter warning as for gas: remove as much grease and food residue as possible because it attracts wildlife, and cover the grill if it stays outside.

The thing that ruins a charcoal grill over winter is the ash. Weber says plainly that ashes left sitting in the ash catcher can promote corrosion. Empty it before the grill is put away, not after.

Pellet grills

Traeger's list is about water and pellets. Its spring-cleaning guide opens with the cover: if a grill is stored outside in wet weather, water can get into the pellet hopper, wet pellets expand and can clog the auger, and a Traeger cannot cook with wet wood. Without a cover, the hopper needs to be kept covered and away from any water.

Traeger's checklist:

• Empty the hopper. Traeger says pellets can stay in it short term in dry weather, but should be removed and stored airtight when prolonged rain or high humidity is forecast.
• Store the pellets dry and airtight. In humid regions moisture gets into unopened bags left in a garage, so Traeger says to put bags in a large airtight bin or move them somewhere dry indoors.
• Vacuum the firepot. Remove the grate, grease drain pan and heat baffle and clean the ash in and around the firepot with a shop vac, with every component cold.
• Scrape the grease drain pan and drain tube and empty the grease bucket.
• Wait for the grill to cool, then cover it. Traeger says its covers protect against sun, wind, rain, snow, tree sap and pollen, and not to store the cover inside or under the grill.

The thing that ruins a pellet grill over winter is damp fuel. Traeger says moisture expands the wood and makes pellets crumbly, that crumbly pellets can clog the auger and may fail to ignite, and that poor pellet quality from bad storage is the number one cause of temperature problems. A hopper of pellets left through a wet winter is an auger jam waiting for the first cook. The pellet grill temperature swings guide starts from the same place.

Gas griddles

A griddle top is bare seasoned steel, so Blackstone's storage advice is about keeping water off it. For an extended layoff its help centre says to clean grease and debris off the body with mild soap or a degreaser and a non-abrasive rag, clean the griddle plate and empty the grease cup to deter pests and avoid mold, add an extra layer of oil to the plate so the seasoning does not dry out and peel, and fit a soft or hard cover. If a soft cover goes on without a hood or hard cover underneath, tent it with an object so water runs off. In a humid or harsh winter climate, Blackstone says to store the griddle in a sheltered area such as a garage. Blackstone's instruction for the propane tank: closed, disconnected, upright on a sturdy surface, and never in an area connected to the house.

The thing that ruins a griddle over winter is rust, and Blackstone is specific about the mechanism. Rust forms when steel meets water and oxygen, seasoning is the polymer layer that locks both out, and water pooling on an unused griddle eats through that seasoning. Its rust-prevention list adds one option the storage page does not: remove the griddle plate and store it indoors. Blackstone's safety guide adds a check at least once a month through the winter. Blackstone's griddles are in the griddle category.

Pizza ovens

Ooni's position is that its ovens are built to live outdoors and are not indestructible. It sells waterproof covers for wet weather and says to bring the oven inside for a blizzard or hurricane. For longer layoffs its advice tightens: store the oven indoors when possible, especially for extended periods, out of direct sunlight and away from snow, heavy rain and strong wind, and cover it whether it is stored inside or out. The Karu 12 FAQ says the same in one line: it can stay outdoors all year under its cover, but Ooni recommends indoor storage for extended periods without use and to protect it from harsh weather.

Ooni's checklist:

• Burn off food debris by running the oven at top temperature for 30 minutes, then brush the stone once cool. Never wash the stone with water or soap.
• Wipe the exterior with a damp cloth and dry it at once, since Ooni says leaving the oven wet encourages rust.
• Take the stone out and keep it indoors between cooks, once fully cooled.
• Cover the oven, and store it inside if it will sit for months.
• On a gas model, Ooni's manual gives the same cylinder rule as Weber's: the gas cylinder is stored outdoors, never in a building, garage or other enclosed area, and if the oven is stored indoors the cylinder is detached and left outside.

The thing that ruins a pizza oven over winter is the stone. Ooni's stone-care guide says the stone is porous and absorbs moisture, that a soaked stone may break the next time it heats up, and that sudden temperature changes cause cracks. A stone that sits in an uncovered oven through a wet winter is exactly that soaked stone. Ooni's cold-weather guidance turns the same fact into an advantage: a stone stored at home starts dry and warm.

The spring check

Before the first cook, Weber's manual says the grill should be checked for gas leaks and burner obstructions, and the manual carries that procedure. Blackstone says that after a couple of months idle you should lift the flat top and look for insects, spiders or other animals nesting in the burner frame, because a nest interrupts the propane flow. If mice or mold found the grill anyway, Weber says to clean out what they left and run the grill on high for at least 15 minutes before cooking. Pellets that crumble between two fingers go in the bin, not the hopper. All of it is cheaper than a burner tube or a stone.