Ask a Master Gardener: Fire-resistant landscapes | Home And Garden

Question: I just finished building a new home in a foothill area and am very aware that wildfire is a real threat. My goal is to create a landscape that is both fire-resistant and drought-tolerant. Any suggestions?

Answer: With the continuing drought and frequent threat of summertime wildfires, it is a great idea to plant fire-resistant landscapes that only require a minimum amount of water.

When planting, carefully consider the spread of the plants when mature, and plan accordingly, so that all plants remain 3 feet away from any wood siding on your home. Concentrate on creating a defensible space with a 30 foot radius around your home that is comprised of fire-resistant plants and other landscape features such as boulders, bricks, rock planters and water features such as a pool or pond.

These hard surfaces will provide firebreaks and increase the likelihood of your home surviving a wildfire.

In general, fire-resistant plants are those that are low growing, retain moisture and contain low sap or resin. Fire-resistant plants can be damaged by fire, however, they will provide only a minimal amount of fuel to feed a raging wildfire.

It is also critical to provide space between all plants. This will reduce the amount of available fuel. Wildfires can jump horizontally from shrub to shrub and tree to tree. The open space between plants (or between groups of plants) reduces the intensity of a wildfire and slows the spread of fire.

Wildfires can also jump vertically, so you will need to create a significant separation between the shrubs and trees. The best defense would be to avoid planting shrubs underneath trees.

Within the 30 foot zone, it is important to keep the plants green and growing especially throughout fire season. Remove any dead vegetation and branches as well as piles of dead leaves and twigs under plants.

Keep plants pruned to reduce the quantity of available fuel. Remove combustible leaves, pinecones and branches from your roof and gutters. Good landscape housekeeping will make a significant contribution in maintaining a landscape that may save your home from being destroyed by wildfire.

Some examples of fire-resistant and drought tolerant groundcovers are rockrose, ice plant and succulents. In particular, the yellow ice plant (Delosperma nubigenum) and the purple ice plant (Delosperma cooperi) would make excellent choices because they are beautiful and hardy.

Other good choices are Snow-In-Summer (Cerastium tomentosum), Carpet Bugleweed (Ajuga reptans) and Creeping phlox (Phlox subulata). These are all beautiful additions to any landscape.

There are many choices available when selecting fire-resistant shrubs. Here are just a few:

  • Butterfly bush (Buddleia davidii) is a colorful and fragrant shrub that grows quickly in the spring up to 10 feet. This shrub needs good drainage and enough water to maintain growth. In midsummer, small, fragrant flowers grow in dense clusters.
  • Western spiraea (Spiraea douglasii) is easy to grow in all kinds of soil. It grows well in full sun or light shade. It grows 4-8 feet tall and 3-6 feet wide with dark green leaves, velvety white beneath. From July to August, the flowers grow densely in variations from pale pink to deep rose.
  • Western azalea (Rhododendron occidentale) is an upright shrub with attractive white to salmon-pink flowers that bloom May to June. It grows 5-10 feet tall and 5-10 feet wide. It requires a medium amount of water and grows well in full sun or shade. It attracts butterflies and is deer resistant.
  • Mock Orange (Philadelphus species) is native to Oregon. The plants are large and vigorous with medium green foliage. It grows 7–10 feet tall and 5-7 feet wide. Mock Orange grows well in full sun or light shade, in ordinary garden soil, and needs medium watering.

If you are going to plant trees, select hardwood trees such as maple, poplar and cherry. The online document referred to below will give you many other choices for trees.

Since you are working with a blank slate, so to speak, you have the perfect opportunity to design your landscape so it is fire-resistant and drought-tolerant. For homeowners with an established landscape, the above suggestions should be helpful when you need to replace old plants.

Working toward a fire-resistant landscape is important for all of us, whether country dwellers or city folk. There is a 48 page document available for free download online that provides so much more detail on this topic.

Do you have a gardening or insect question? Contact the Douglas County Master Gardeners via email at [email protected]. Douglas County Master Gardeners are trained volunteers who help the OSU Extension Service serve the people of Douglas County.