- Although plants do retain topsoil, they cannot be counted on to provide structural support to unstable slopes. Unstable slopes may require significant grading or slope modification by a qualified engineer.
- Create small terraces to hold water and soil while plants are becoming established and root systems are developing. Place new plants toward the outside of the slope so that debris from the slope does not collect around the plant crown or stem resulting in crown rot.
- Plant selection:
- Cover slope with both rapid-growing short-lived, and slow-growing long-lived plants.
- Select plants with extensive, wide spreading root systems.
- Use a variety of plants. Large shrubs with extensive root systems should be given adequate space to develop. Smaller plants and low groundcovers can be placed between larger plants to further reduce soil erosion. Include plants with taps roots and those with fibrous roots.
- Supplemental irrigation is usually needed during the establishment period. The watering practice should assist deep rooting - water in short periods with intervals between watering to facilitate percolation and reduce runoff. The time periods for and between the application of water will vary depending on the type, texture and composition of the soil. Careful observation will allow you to establish effective watering schedules. Remember that upper slope areas will dry more quickly, while lower slope sections may become over-saturated.
- Jute netting tacked down on exposed slopes will help reduce erosion and keep plants in place as their roots develop. Mulch is not much help since much of it washes off during rains.
- If you have fire concerns, be sure to consult other references for plant selection and proper horticultural practices aimed at reducing fire risk.
Short list of easy-to-grow California native plants for use on slopes*
* For fire concerns, consult your fire department and plant lists specifically addressing fire safety issues.
Achillea millefolium (common yarrow)
Adenostoma fasciculatum (dwarf chamise)
Arctostaphylos edmundsii (big sur manzanita)
Arctostaphylos hookeri (Hooker manzanita)
Atriplex lentiformis brewerii (quail brush)
Baccharis pilularis (coyote brush)
Baccharis pilularis ‘Pigeon Point’ (dwarf coyote brush)
Baccharis pilularis ‘Twin Peaks 2’ (dwarf coyote brush)
Ceanothus spp. (wild lilac)
Encelia californica (coast sunflower)
Eriogonum fasciculatum (California buckwheat)
Heteromeles arbutifolia (toyon)
Iva hayesiana (San Diego marsh-elder)
Keckiella antirhinoides (yellow penstemon)
Malosma laurina (laurel sumac)
Rhus ovata (sugar bush)
Rhus integrifolia (lemonadeberry)
Salvia leucophylla (purple sage)
Salvia leucophylla ‘Pt. Sal Spreader’ (purple sage)
Salvia mellifera (black sage)
Salvia mellifera ‘Terra Seca’ (dwarf black sage)
Yucca whipplei (chaparral yucca)