Why defensible space works
A wildfire moving across the ground needs continuous fuel to keep advancing. Defensible space deliberately breaks that continuity. By thinning, spacing, and choosing what grows near your home, you lower the intensity of any fire that reaches the property and deny it a path to your walls. The aim in the outer zones is not to remove every plant — it's to reduce how hot and how fast fire can burn.
Fire-resistant plants do not readily ignite from flame or embers, but they can still be damaged or killed by fire. Their value is that their foliage and stems don't significantly add fuel — they don't carry fire toward your home the way dry, resinous, or woody vegetation does.
Choosing plants
Favour plants that hold moisture and stay low in resin and oil. As a general guide, fire-resistant landscaping leans on:
- High-moisture, broadleaf plants — many deciduous trees and shrubs, and lush, well-watered perennials and groundcovers.
- Low, green, well-maintained vegetation kept watered through fire season rather than allowed to dry out.
- Avoiding conifers, junipers, ornamental grasses, and other resinous or oily species close to the home — these ignite readily and burn hot.
Because the right species depend on your region and climate, match selections to local guidance. Flash Wildfire Services maintains a regional plant primer: fire-resistant landscaping plants for your region.
Tree & crown spacing
In the extended zone (10–30 metres), spacing is what stops a fire from climbing into the canopy and racing tree to tree:
- Maintain at least 3 metres of horizontal space between evergreen tree crowns.
- Prune evergreen branches to 2 metres above the ground so a surface fire can't ladder up into the crown.
- Keep groups of trees, rather than a continuous unbroken canopy, with breaks that interrupt fire spread.
Remove ladder fuels
"Ladder fuels" are the rungs that let a low surface fire climb into taller vegetation and ultimately the tree crowns — think tall grass under shrubs, shrubs under low branches, low branches into the canopy. Breaking that vertical chain keeps fire on the ground, where it's lower intensity and easier to stop. Clear vegetation from beneath trees and around outbuildings, propane tanks, and other infrastructure.
Mulch & ground materials
What you put on the ground matters as much as what you plant. In the 1.5 metres against the home, use only non-combustible surfaces — gravel, brick, or concrete. Keep bark mulch and woody debris out of that immediate band; it's prime ember fuel right where you can least afford it. Further out, manage mulch depth and keep it away from structures.
Build a seasonal routine
Defensible space isn't a one-time project — vegetation grows back and debris re-accumulates. A simple recurring routine keeps you ahead of it:
- Clean gutters and roof valleys of needles and leaves.
- Mow grass to under 10 cm and keep it watered.
- Clear fallen branches, dry grass, and needles.
- Re-check tree spacing and prune new low growth.
Our seasonal maintenance calendar turns this into a printable, month-by-month checklist.
Next: Evacuation & Emergency Planning →
Spacing and vegetation guidance adapted from FireSmart Canada and FireSmart Alberta. See About & Sources.