Ask a Master Gardener: Fire-resistant groundcovers for the Oregon landscape
Question: I need some specific examples of groundcovers that are both fire-resistant and drought tolerant that grow well in our climate zone and would be attractive in my landscape design.
Answer: With the continuing drought and frequent threat of summertime wildfires, it is a great idea to plant fire-resistant groundcovers that only require a minimum amount of water. When planting, carefully consider the spread of the groundcover when mature, and plan accordingly, so that the groundcover remains three feet away from any wood siding on your home. And with all fire-resistant landscaping, it is important to provide adequate water and frequent removal of old, dead parts. There are many groundcovers that meet all of your requested attributes.
One type of hardy and beautiful groundcover is found in the ice plant family. All are drought tolerant once established. They do need some water during the summer, and the amount depends on the heat and humidity. Be careful not to overwater because too much water will cause dieback. All need full sun and will tolerate most soils. They will not do well if walked upon. The yellow ice plant (Delosperma nubigenum) and the purple ice plant (Delosperma cooperi) bloom June through September. They will be about 1-4 inches tall with a mature spread of 24-30 inches. Both do well in rock gardens.
One groundcover that grows well in all climate zones is Snow-In-Summer (Cerastium tomentosum). This groundcover will have an abundance of snowy, white masses of flowers in early summer. The plant does best when planted in full sun and in any soil with good drainage. Snow-In-Summer will grow to about 6-8 inches tall and will spread 2-3 feet in one year. It is especially beautiful when planted so that it cascades from the top of garden walls but is also frequently planted between stepping stones and the edges of paths. Once established, only occasional watering is needed.
Carpet Bugleweed (Ajuga reptans) is a popular groundcover that will grow well in full sun and in part shade. There are many varieties available. This groundcover spreads by runners and makes a mat of dark green, bronze, purple, or variegated foliage. Mostly blue flowers bloom in 4- to 6-inch spikes from spring to early summer. Keep the old flower spikes trimmed off. During the summer, water every 7-10 days. This plant will grow about 4-10 inches tall and will spread about 12-18 inches. To prevent problems with root-knot nematodes, rot and fungus disease, it is best to plant in well-drained soil.
Creeping phlox (Phlox subulata) forms a dense mat up to 6 inches tall with creeping stems that can spread out 18-24 inches. This groundcover is known for its showy display of either white, pink, rose and lavender-blue flowers in late spring to early summer. After flowering, cut back halfway. It grows best in full sun and does well in rock gardens. Quite often, you will see this plant growing from crevices in stone walls. Well-drained soil is best. As an added bonus, Creeping phlox attracts butterflies and is relatively deer-resistant.
These groundcovers are all fire-resistant, drought-tolerant and beautiful, which make them a good choice for your Oregon landscape. There are many more choices available. If you want more ideas, visit the Discovery Garden located at 238 River Forks Park Road or visit the trained volunteers at the Plant Clinic.