Keeping Defensible Space Up Through Montana's Fire Season

What changes on a property between spring and August?

Almost everything that burns. Spring grass that was green and harmless in May is cured and standing by midsummer. Conifers drop needles through the season. Shrubs put on a year of growth toward the house and toward each other. Patio furniture, cushions, doormats and firewood find their way back into the five feet next to the house because that is where people live in summer.

The Colorado State Forest Service's home ignition zone guide says the home ignition zone needs regular, ongoing maintenance because trees, grasses and shrubs keep growing, dying and dropping leaves each season. It marks several tasks as ones to address as needed, more than once a year: clearing roofs, decks and gutters, mowing grass and weeds to four inches or less, raking needles out of the five feet around the house and deck, and keeping chipped slash 30 feet or more from the home. Those are the summer list.

How short should grass be kept in fire season?

The Colorado State Forest Service guide recommends mowing grasses to four inches or less in the zone around the home, and notes that mowing is not necessary in the outer zone farther out. It also warns that grass fuels can readily ignite structures directly next to them, so this matters most where grass runs up to a deck, a fence, a shed or the foundation.

Irrigated lawn near the house is a different fuel from dry pasture grass at the property edge. The University of Nevada, Reno Extension's Wildfire Home Retrofit Guide describes the band from five to 30 feet as lean, clean and green: sparse vegetation, dead material routinely removed, and plants kept green and well irrigated during fire season where appropriate. See lawns and irrigation as fire breaks for how to set that band up.

When is it safe to mow or run equipment in summer?

Early. Keep Montana Green advises starting grass and vegetation clearing before 10 a.m., because afternoon heat, lower humidity and stronger wind raise the fire risk. It warns that a rock or debris hidden in tall grass can start a fire when struck by a metal blade, so walk the area first and pull anything a blade could hit.

Keep Montana Green also states that spark arrestors are required on all portable, gasoline-powered equipment, including chainsaws and mowers. Carry a shovel and water when you work in dry grass, and stay with the area for a while after you finish. The same caution is why our own crews avoid cutting in hot, dry, windy conditions and plan tree work outside the peak of the season.

How do fire restrictions affect yard work?

They can. The Missoula Fire Department notes that fire restrictions change with the season and points residents to MTFireInfo.org for current restrictions. Check what is in force for your area before you burn anything or run power equipment in dry grass.

Missoula County Public Health lists the general outdoor burning season as March 1 to August 31, and Ravalli County runs its burn permit process from March 1 to November 30, but a permit season being open does not mean burning is allowed on a given day. Permits have to be activated before burning, and Ravalli County requires it each day you plan to burn. Our fire restrictions guide explains the stages.

How often should gutters and roofs be cleared in summer?

As often as needles land on them. The UNR guide says to remove vegetative debris from gutters on a regular basis during fire season and to clear roofs regularly, because embers settle where debris collects: in valleys, behind gutter guards, at roof-to-wall joints and around chimneys. DNRC's west-central Montana landowner guide also tells owners to regularly clean the roof and gutters.

A house under mature ponderosa pine can need this more than once over a summer, especially after a windy stretch. The detail is in roofs, gutters and valleys, and the needles themselves are covered in our pine needle cleanup guide.

What about mulch, decks and patio furniture?

Montana State University Extension's MontGuide on fire-resistant plants warns that sparks and firebrands can ignite bark mulch, and advises keeping wood mulch moist when fire is in the area or replacing it with rock mulch. In the first five feet, IBHS lists combustible mulch, wood fences and outdoor furniture among the fuels to remove from next to the house.

Decks collect what the wind brings. The UNR guide recommends a noncombustible zone under and around decks, clearing debris from under the deck routinely, and moving combustible cushions inside and furniture away from the house. The Colorado guide adds: do not use the space under a deck for storage. Our under-deck prep guide and mulch guide go further.

Where should firewood and propane be in summer?

Away from the house. The Colorado State Forest Service checklist says to keep firewood at least 30 feet from the home, stacked uphill from or level with structures, not between trees or on or under the deck, and to clear flammable vegetation within 10 feet of woodpiles. It recommends keeping aboveground tanks at least 30 feet from the home and clearing flammable vegetation within 10 feet of propane tanks and gas meters.

Firewood that came in close for the shoulder season in spring should go back out before summer. We cover the details in where to stack firewood and propane tank clearance.

Do sheds and outbuildings need summer attention too?

Yes, because a burning shed next to a house exposes the house to the same flames and heat as a burning woodpile. The UNR guide recommends locating outbuildings used for storage at least 30 feet from the home and creating an ember-resistant zone around all outbuildings and propane tanks. In summer that means the same routine as the house: no dry grass against the walls, nothing combustible stacked along the sides, and needles off the roof.

Shops and barns tend to collect fuel cans, lumber offcuts and hay, which are exactly the things embers find. Our guides to sheds and outbuildings and barns, hay and livestock go through them in detail.

How do you keep the green zone green without wasting water?

Water deeply and on a schedule that matches the weather, and fix the problems that waste it. A head spraying a fence instead of the lawn leaves a dry strip exactly where the green band is supposed to be. For trees in the green zone, MSU Extension's drought stress guidance says to water slowly and deeply rather than quickly and shallowly, and notes that trees planted in the last three years are the most likely to suffer permanent drought injury.

Our summer lawn watering guide and watering windows guide cover schedules, and our sprinkler repair crew can find the leak or the dead zone.

What should you not do in summer?

Do not start big thinning or limbing projects in pine during the hot months unless the slash will be removed immediately. The USDA Forest Service's pine engraver guide rates pine slash created from April through July as extreme risk for beetle infestation, because the beetles are actively looking for fresh material. It notes that chipping creates volatiles that can attract pine engravers for up to two weeks.

Summer cutting also brings the ignition risk the work is meant to prevent. That is why we plan larger fuel reduction outside the peak of summer, covered in why fall and winter are the best time for fuel reduction. Summer is for upkeep: mowing, raking, needles, water and moving things away from the house.

What if a fire is already nearby?

Follow official instructions and leave early if told to. The UNR guide describes pre-made vent covers that can be installed when fire threatens, but cautions that this only makes sense if there is ample time before evacuation, because preparation activities become dangerous if they delay leaving. It also recommends closing windows and garage doors and adding a battery backup to the garage door opener so the door works if the power is out.

Plan this in spring, not during the evacuation. The Ready, Set, Go guide has the household side.

Getting help through the season

Summer upkeep is the part of defensible space that falls apart when owners travel, rent the place out or simply run out of evenings. Our seasonal cleanups and lawn care keep needles, debris and grass in check, and our fire mitigation crews do the near-structure cleanup. The year-round view is in the defensible space maintenance schedule, part of our Montana Wildfire Guide. Call HJ Property Care & Tree Service at (406) 215-7319 or request a free estimate and we will walk the property with you.

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