Elisabeth C. Miller Library logo Miller Library Home UW Botanic Gardens Home UW Botanic Gardens Home book graphic

3501 NE 41st Street, Seattle, WA 98195 | (206) 543 0415 | Open: | Library Schedule

Gardening Answers Knowledgebase

Plant Answer Line Question

Keywords: Berberis, Vaccinium ovatum, Polystichum munitum, Amelanchier, Acer circinatum, Slope stabilization and soil erosion, Corylus, Alnus, Philadelphus lewisii

Can I plant groundcovers, shrubs, and trees to stabilize a steep slope?


There are several resources which will help you in selecting plants to prevent erosion and mudslides on your slope.

Please note that these articles are merely suggestions and should not be construed as advice. We are librarians, not engineers!

None of our standard books on trees mentions the soil binding quality of tree roots. However, the Miller Library does have very good technical books and articles on slope stabilization. (For example, Slope Stabilization and Erosion Control: A Bioengineering Approach, edited by R.P.C. Morgan and R.J. Rickson, 1995.)

I do want to note one thing that many articles mention: no amount of established vegetation will hold a steep slope if other forces are present that would contribute to a landslide.

The Department of Ecology website has a list of appropriate plants.

Additionally, there are a number of books with information on the subject. Vegetative Contribution to Slope Stability at Magnolia Park (by Kathy Parker, 1996) recommends Oregon grape (Mahonia), which she suggests for gentle slopes.

Other smaller plants she lists are:
Polystichum munitum (native sword fern)
Vaccinium ovatum (evergreen huckleberry)
Symphoricarpos albus (snowberry)

Larger shrubs in her list:
Alnus rubra (red alder)
Philadelphus lewisii (mock orange)
Sambucus racemosa (red elderberry)

Small trees:
Acer circinatum (vine maple)
Amelanchier alnifolia (serviceberry)
Corylus cornuta (hazelnut)

For steeper slopes, Parker says that they may not be good candidates for vegetative rehabilitation unless you put in some kind of structure. She says that Jute mats can be used in conjunction with native seed, mulch, and shrubs, if carefully anchored. She also mentions a Weyerhaeuser product called Soil Guard.

Steep Slope Stabilization Using Woody Vegetation (by Leslie Hennelly, 1994) has a plant list, as well as a chart which indicates plants used to control erosion, the degree of the slopes, and the rate of success in resisting erosion.

Two titles which focus more on the garden design aspect of planting on a slope are Hillside Gardening : Evaluating the Site, Designing Views, Planting Slopes (by William Lake Douglas, 1987) and Hillside Landscaping (by Susan Lang and the editors of Sunset Books, 2002).

Date 2018-06-14
Link to this record only (permalink)

Plant Answer Line Question

Keywords: Amelanchier

I am a landscape designer, and I want to use Amelanchier in my design. Which species are most readily available in the trade? I have seen some which have a single trunk, and others which are multiple. Is the growth habit specific to the species or cultivar?


From what I can tell by searching Plant Information Online, there are quite a few cultivated varieties and species of Amelanchier which are widely available from both retail and wholesale sources.

As far as which species and cultivars are more likely to have single or multiple trunks, I found a few descriptions in Dirr's Hardy Trees and Shrubs by Michael Dirr (Timber Press, 1997.

  • Amelanchier arborea is described as "a small tree or a large multistemmed shrub of rounded outline."
  • Amelanchier canadensis "is hopelessly confused in the landscape trade. In general, it is an upright, suckering, tightly multistemmed shrub with a dome-shaped crown."
  • Amelanchier x grandiflora is "a naturally occurring hybrid between Amelanchier arborea and A. laevis. It exhibits characteristics intermediate between those of the parent species [...] The best of the [cultivars] include: 'Autumn Brilliance,' with red fall color, 'Ballerina,' with brick-red fall color, and 'Princess Diana,' with red fall color. 'Robin Hill' and 'Rubescens' have pink buds that fade upon opening."
  • Amelanchier laevis is "not too different from the other species, especially Amelanchier arborea, in flower, fruit, bark, and growth habit. The principal differences are the purplish to bronze color of the emerging leaves and lack (almost) of hairs on the leaves and flower stalks."

Here at the Center for Urban Horticulture, we have a grove of Amelanchier x grandiflora, all of which are multi-stemmed. Arthur Lee Jacobson lists several additional species in his North American Landscape Trees (Ten Speed Press, 1996), including the Northwest native Amelanchier alnifolia, which he says is "little planted, especially as a tree." Its leaves are rounder, with coarser teeth. It flowers later, and its fall color is inferior. Its berries are larger.

You might also explore the Oregon State University Landscape Plants database to see comparative images and descriptions.

If you want to intervene and shape the growth habit of Amelanchier, the American Horticultural Society's Pruning & Training (edited by Christopher Brickell; DK Publishing, 1996) says that this "upright, multi-stemmed shrub can be allowed to develop naturally with minimal pruning. It may also be trained with a short trunk to form a small, branched-headed tree." The time to prune would be when dormant in the winter, or after flowering in late spring.

Date 2017-08-24
Link to this record only (permalink)

Garden Tip

Keywords: Rosa, Garden design, Amelanchier, Sedum, Hydrangea

It's easy to plant a garden that is colorful and interesting in June, more difficult is designing a garden that shines in October. Read Autumn Gardens by Ethne Clark (Soma, 1999) to learn both design principles and the best trees, shrubs, perennials, bulbs and grasses to plant in fall. Oakleaf hydrangea, Canadian serviceberry, species roses, and sedums are just a few of the plants featured that will extend the garden interest beyond Labor Day.

Date: 2007-07-13
Link to this record (permalink)

Didn't find an answer to your question? Ask us directly!

Browse keywords

Search Again:

May 31 2018 13:14:08