With the arrival of September, northern Nevada is entering one of the best times of the year to plant landscape vegetation. The cooler air temperatures and warm soils are the perfect combination for establishing new plants. Now is a good time to replace flammable vegetation with less hazardous options.
One of Nevada’s most popular landscape plants are ornamental juniper shrubs and they are often used in mass plantings adjacent to houses. They are drought tolerant, stay green year-round and require little care. Unfortunately, as they mature they often become a fire hazard. Several attributes contribute to the juniper’s notorious reputation as a threat:
- Ornamental junipers have a bad habit of retaining clumps of dead leaves and dead branchlets within their crowns. Pull back the branches of a mature juniper and see for yourself. These little “jackpots” of fuel are easily ignited by windblown embers produced by the wildfire. Thick layers of dead plant debris also build up underneath the shrubs. Since the juniper branches are so thick and the leaves can be irritating to the skin, most people don’t remove the plant litter or don’t notice it.
- They are dense plants. There is usually a lot more plant material, or potential fire fuel, in a 3-foot tall juniper than there is in other similar sized, more open-branched deciduous shrubs. For example, compare a juniper to a red twig dogwood.
- Like most coniferous plants, junipers contain volatile oils. These chemicals can cause a juniper to burn intensely.
Junipers ignited by embers were identified as a contributing factor to the loss and damage of homes during the recent Caughlin Fire and in other wildland-urban interface fires in the West. A 2006 study evaluated the combustibility of 34 shrub species. Ornamental juniper was ranked as one of the most flammable plants tested and the authors recommended that they not be planted close to structures. In Nevada, we recommend removing mature ornamental junipers within 30 feet of your house and replacing them with more desirable choices, such as:
- Herbaceous plants, such as lawn, annual and perennial flowers and bulbs, that are kept green via irrigation during fire season.
- Low growing (i.e., less than 2 feet in height) deciduous shrubs that are under irrigation.
- Noncombustible landscape materials, such as gravel, rock and pavers.
For more information on good plant choices, go to http://www.livingwithfire.info/learning-center and download the publication “Choosing the Right Plants for Northern Nevada’s High Fire Hazard Areas.” You can also receive a hard copy of this publication by contacting your local University of Nevada Cooperative Extension office.