Marin Master Gardeners
University of California
Marin Master Gardeners

Fire-smart Landscaping - Choosing Plants and Spacing

Spacing plants
Plants and spacing quick check list:

  • Right plant, right place – healthy plant. Consider the plants preference for soil type, water, and sun
  • Plant characteristics include
    • ability to store water in leaves and stems,
    • produce limited dead and fine material,
    • maintain high moisture content with limited watering,
    • low-growing or open form,
    • low levels of volatile oils or resins,
    • slow growing with little maintenance
  • Group plants that require similar amounts of water so that all plants can be irrigated appropriately
  • Arrange plants, trees and shrubs with horizontal and vertical clearance from structures and each-other to disrupt a fire
  • Trees and shrubs are small when purchased, be aware of height and width at maturity
  • Replace invasive plants with native or well-behaved plants. Invasive plants can increase the intensity of fire.  Native plants are suited to our Mediterranean climate and soil types and require less maintenance and water

“When creating a fire-smart landscape, we advise homeowners to design defensible space and maintain their landscapes according to UC Marin Master Gardener guidelines. For a new or renovated landscape, consider native or other pollinator-friendly plants that require little water and are easy to maintain.  There are no published fire-wise or fire-resistant plant lists that are science-based or peer-reviewed.  Design and maintenance are more important than plant selection.”

- Steven Swain, UC Cooperative Extension Environmental Horticulture Advisor, for Marin and Sonoma Counties

Planning:  Whether you want to modify an existing garden or create a new garden, planning will save you time and money.   Creating a fire-smart landscape can feel overwhelming.  Start with small fixes.  Perhaps you simply start by assessing the spacing of plants in your garden.

Beginning steps: If you want to replace a plant or a section of plants, start with the fundamentals by assessing the soil, your local microclimate, and access to water.  Once these fundamental building blocks are in place, then consider how much maintenance you want to take on. 

Plant Selection:  Healthy plants are more fire resistant than plants struggling to survive.  Thoughtful and informed plant selection and siting can reduce the threat of wildfire, cut maintenance costs, and help solve the growing problem of biomass disposal not only on our own properties, but in our neighborhoods and on a regional scale. If you do seek out a plant list to get started, make sure it’s local to your area. 

Trees

  • Choose trees that are low in resin and sap content
  • Choose native trees that have adaptations to fire such as thick bark. These trees have a higher tolerance for fire and help restrict the growth of more volatile invasive and shrub species.
  • Space trees so that at maturity their crowns are fifteen feet apart or more. The greater the spacing between trees, the less likely that fire will spread from one to another.
  • Avoid planting trees in rows or hedges, since this can provide an uninterrupted path for fire.
  • Try to select trees that shed minimal amounts of needles, leaves, fronds, dry bark and other waste
  • Avoid trees that have dead thatch inside or under a green surface layer

Shrubs

  • Avoid planting shrubs in rows or hedges, since this can provide an uninterrupted path for fire. Discrete “islands” of plants are less likely to spread a fire. Ideally, island width should be no more than two times the height of shrubs and at least that distance apart.
  • Avoid massing shrubs at the bases of trees or adjacent to structures, especially under eaves, overhangs, windows, or decks.

Native Plants

  • Use drought tolerant native plants that can maintain a high internal water content without needing a lot of water.
  • Group similar plant communities that are locally adapted

Invasives

  • Do not plant invasive species and consider removing them. Invasive plants can escape yards and form continuous fuel beds in unmanaged areas, while damaging native habitat for wildlife

Reference Materials for further reading:

Preparing Your Landscape: https://ucanr.edu/sites/fire/PrePost/Landscaping/

Native Plants:  http://marinmg.ucanr.edu/Choose_Plants/Native_Plants_574/  

Choose Plants: http://marinmg.ucanr.edu/Choose_Plants/

Choosing Your Native Plants: https://www.cnps.org/gardening/choosing-your-plants

SelecTree:  A Tree Selection Guide: https://selectree.calpoly.edu

Waterwise Plants: http://marinmg.ucanr.edu/Choose_Plants/Plant_Guide/

Trees and Shrubs: http://marinmg.ucanr.edu/Choose_Plants/Trees_Shrubs_-_Vines/

Plant Care: http://marinmg.ucanr.edu/Manage_A_Garden/Plant_Care/

Tree Care: http://marinmg.ucanr.edu/Manage_A_Garden/Tree_Care_162/

Fire Resistant Plants:  https://ucanr.edu/sites/fire/PrePost/Landscaping/Plant_choice/

Sustainable and Fire Resistant Landscapes: http://ucanr.edu/sites/SAFELandscapes/Invasive_Plants_and_Wildland_Health/

Protecting California’s environment and economy from invasive plants:  https://www.cal-ipc.org

Plant right: https://plantright.org

Trees: https://ucanr.edu/sites/fire/PrePost/Landscaping/Trees/

Near-Home Vegetation: https://ucanr.edu/sites/fire/PrePost/Building/Plants/

What is My Climate Zone: http://marinmg.ucanr.edu/Weather_-_Climate_Problems/Climate_Zones/

Lawn Care: http://ipm.ucanr.edu/TOOLS/TURF/

Webmaster Email: banielsen@ucanr.edu