Safety Tips for Burning Native Prairie

Burning prairie isn't complicated. Burning it safely takes a little more thought.

Every spring, somebody loses a fire to a neighbor's woodlot because they didn't have the right weather, didn't have the right crew, or didn't think through their break before they struck a match. It happens to people who aren't careless — it happens to people who just didn't know what they didn't know.

On a recent episode of the Prairie Farm Podcast, Nicolas and Kent sat down with Ray Geroff, a district heritage biologist for the Illinois Department of Natural Resources who has burned more than 100,000 acres of prairie across his career. He burned 3,900 of them the day before the recording. Ray knows fire. Here's what he says keeps burns from going sideways.

Know Your Weather Window

There's probably nothing more important to a safe burn than understanding your conditions — and having the discipline to wait for them.

For wind, Ray's DNR crews target 20 mph or less at the 20-foot wind speed. That said, wind direction matters as much as speed. A steady breeze from a consistent direction before, during, and after the burn is what you want. USDA's prescribed burn guidance for Illinois puts the sweet spot at 4–15 mph for most situations — calm enough to control, enough wind to carry the fire and disperse smoke. Gusty, shifting winds are a no-go. If there's a forecasted front or wind shift within 12 hours, Extension's Prescribed Fire program recommends holding off entirely.

For humidity, Ray said his DNR crews will burn as low as 20% relative humidity — but that's with professional crews and tested sites. For most landowners, the 60:40 rule is a good starting point. Temperatures under 60°F and relative humidity above 40%, with wind in that 5–15 mph range. As Ray put it directly on the podcast: "When you get down into the teens, pretty much everything's going to start catching fire." A single ember on a 15% humidity day can catch the base of a snag tree that would have brushed it off at 40%. The upper end matters too — above 70–75%, you're not going to get a productive burn regardless.

Temperature rounds it out. Conservation managers at Schlitz Audubon put the optimal range at 40–60°F, with above 80°F considered hazardous.

One thing Ray emphasized: check conditions right before the burn, not just the night before. Humidity can shift fast when a cold, dry air mass rolls through.

Build the Right Burn Break

A burn break is what keeps your fire where it belongs. Roads, ponds, and plowed fields are ideal natural anchors. Where those don't exist, you build one, and Ray was pretty specific about how.

On tall grass prairie, he mows three passes with a 6-foot mower deck to get roughly 18 feet of cleared material. That gives crew and equipment a place to stand back from the main heat. But here's the part most people miss: a mowed break alone might not hold. As Ray explained on the show, "just because you mowed it in doesn't mean it won't burn across that thatch that's there could still burn across that break." The real protection comes from building black — using a backing fire to burn into your break and widen the non-flammable buffer before you ever send a head fire toward it.

A good rule of thumb is to make your break at least 1.5 times the expected flame height. On a site with 6-foot switchgrass, that means you need considerably more than 6 feet of mowed material.

One specific hazard Ray mentioned: snag trees. On low-humidity days, a single ember can catch in a defect or an animal hole in a dead tree and set the whole thing burning. If a snag catches and it's close enough to throw embers over the line, Ray's crew cuts it down. That's why a chainsaw is on the equipment list for any timber-adjacent burn.

Have the Right Crew and Use Them Right

Most burns that go wrong, Ray said, happen because someone either deviated from the burn plan or didn't have adequate crew support. Those two things cover most of the bad outcomes. The weather variables you can't always control. The plan and the crew you can.

At a minimum, you need drip torches, backpack water pumps, and a reliable water source before you light anything. Know your crew's roles before the fire starts — who's on the flanks, who holds the ignition, who's watching the most vulnerable part of the break. Communication during a burn matters more than most people expect.

Don't leave the site until there's been no smoke for at least an hour. Walk your perimeter after the fire's out. A hot spot in a root mass that looks dead can smolder overnight and relight.

Call Before You Burn

Iowa doesn't require a permit for private landowners burning their own ground — unlike Illinois, where Ray said landowners are technically supposed to have an approved burn plan and an Illinois EPA open burning permit (a rule most private landowners, he admitted, don't even know exists). In Iowa, calling your local county dispatch or fire department ahead of time is the right move even if it isn't required. It takes two minutes and means nobody sends emergency response when they see smoke on the horizon.

Urban and Backyard Burns

A lot of Hoksey customers have smaller pollinator patches in their yards and wonder whether burning is realistic. Ray's answer was yes — but with extra care. Check local ordinances first; many municipalities have specific rules about hours, permits, and smoke. On the question of mowing before you burn, Ray pointed out that mowing a pollinator planting that's surrounded by lawn can actually benefit the cool-season grass more than the planting. For small patches, he suggested fall or early spring burns, and leaving some of the planting unburned to preserve refugia for insects and larvae.

If a pollinator planting is mostly what the insects around it have, burning the whole thing at once means burning up eggs, larvae, and overwintering habitat all at the same time. Burn part of it. Leave the rest.

One More Thing

It's worth mentioning: Ray described how his DNR burns go through multiple levels of review before anyone strikes a match — fire program manager sign-off, permits, crew specifications, species checks. Private landowners obviously aren't running that system, but the underlying discipline is the same. Have a plan, know your prescription, meet your conditions, and don't light when something feels off. As Ray put it: "Whenever I get feelings like that, I first usually go back to what's my weather forecast? What do my fuels look like? What's the burn history of this site?"

That's good advice for anyone with a torch in their hand.

Looking to seed after your burn? A post-burn window is one of the best opportunities to get new species established — the seedbed is clean, the soil warms fast, and the competition is suppressed. Hoksey Native Seeds carries what you’ll need for native seeds. If brome is what you're managing against with fire, the Hoksey guide to killing brome and cool-season grasses in existing prairie walks through the full fire-plus-herbicide approach.