Shrubs

What is a shrub? The answer depends on who you talk to. Some plants, such as oceanspray, seem to fit neatly into everyone's concept of what a shrub is. However, with some of the larger and smaller woody plants, there is often a bit of confusion. One expert will say that the coast rhododendron is a shrub, while another calls it a small tree. Other experts contend that kinnikinnick is a low shrub, while some authorities say it is a ground cover.

Shrubs are generally considered to be woody perennial plants of short to medium stature, evergreen or deciduous, usually multi-trunked, which may be either native or introduced. As you can guess from this vague description, there are thousands of plants which could be considered shrubs.

When considering adding a shrub to your garden, it is often worthwhile to look at those plant species which others in our region have had success with. Below are two on-line sources for information on shrubs found to have been successful in the Pacific Northwest, providing an excellent starting point for your shrub investigation. As always, your final decision should be based on your own research, desires, and garden environment.

Great Plant Picks

Great Plant Picks (GPP) is an educational awards program committed to building a comprehensive palette of outstanding plants for Pacific Northwest gardens. Awards are based on the combined expertise of over forty horticulturists from Washington, Oregon and British Columbia. GPP originates at the Elisabeth Carey Miller Botanical Garden in Seattle, Washington, and provides a forum for sharing horticultural information with the wider gardening community.

GPP has assembled a list of outstanding garden plants for the Pacific Northwest region, west of the coastal mountains (The URL for this site can be found at the bottom of this page.) This annual list includes sections on waterwise shrubs, evergreen shrubs for shade, deciduous shrubs for shade, and great hybrid Rhododendrons.

To be included on the GPP plant lists, all plants meet the following selection criteria:

• Be hardy in USDA zones 7 and 8 (0 to 10 degrees F/ -18 to -12 degrees C). Grays Harbor and Pacific Counties are in USDA zone 8.
• Be long lived.
• Be vigorous and easy to grow by a gardener of average means and experience. (Plants don't require specialist knowledge.)
• Be reasonably disease and pest resistant.
• Have a long season or preferably multiple seasons of interest.
• Be available from at least two retail sources in Canada and the U.S.
• Be adaptable to a variety of soil and fertility conditions.
• Not require excessive moisture (with the exception of aquatic plants).
• Not be invasive or overly vigorous in colonizing the garden or larger environment.
• Perennials should not require staking, continual deadheading or frequent division.
• Trees and shrubs should require little pruning and minimal training to achieve their best form (excluding plants used for hedges).
• Bulbs should persist in the garden, without being lifted, for at least three years.
• Variegated plants should be stable and not revert.

The Saving Water Partnership

A surprising on-line source for Western Washington shrub information is The Saving Water Partnership, a consortium of 18 water utilities implementing the 1% Water Conservation Initiative. The Partnership publishes a list of plants which have done very well in Western Washington. Below are the shrubs from their publication, with both the scientific and common names.

• Wet Winter/Dry Summer Shrubs. The following shrubs are some of the best at faring well in very wet winter soils, often due to slow drainage or constant seepage, and dry summer soils.

  Aronia arbutifolia (red chokeberry)
  Aronia melanocarpa (black chokeberry)
  Aronia x prunifolia (purple chokeberry)
  Berberis darwinii (darwin's barberry)
  Berberis thunbergii and cultivars (japanese barberry)
  Cornus alba and cultivars (redtwig dogwood)
  Cornus stolonifera and cultivars (red osier dogwood)
  Gaultheria shallon (salal)
  Myrica californica (california wax myrtle)
  Physocarpus opulifolius (purpleleaf ninebark)
  Potentilla fruticosa (shrubby cinquefoil)
  Sambucus nigra and cultivars (black elder)
  Spiraea douglasii (douglas' spirea)
  Spiraea x vanhouttei (bridal wreath spirea)
  Symphoricarpos albus (snowberry)

• Moisture-Loving Shrubs. Here are a variety of shrubs that can thrive with moist or wet conditions throughout the year, including poor drainage.

  Aronia arbutifolia (red chokeberry)
  Aronia melanocarpa (black chokeberry)
  Aronia x prunifolia (purple chokeberry)
  Calycanthus floridus (carolina allspice)
  Clethra alnifolia (sweet pepperbush)
  Cornus alba and cultivars (redtwig dogwood)
  Cornus stolonifera and cultivars (red osier dogwood)
  Lonicera involucrata (black twinberry)
  Myrica californica (california wax myrtle)
  Physocarpus opulifolius and cultivars (ninebark)
  Salix discolor (pussy willow)
  Salix purpurea (arctic willow)
  Sambucus nigra (black elderberry)
  Sambucus racemosa (red elderberry)
  Sorbaria sorbifolia (false spirea)
  Vaccinium corymbosum (high bush blueberry)

• Favorite Pacific Northwest Native Shrubs. These are among the most garden-worthy native shrubs available in local nurseries. When buying natives, ask to make sure the plants are nursery-propagated to avoid harming natural plant environments in the wild.

  Acer glabrum (douglas maple)
  Amelanchier alnifolia (serviceberry)
  Arctostaphylos uva-ursi (kinnikinnick)
  Cornus stolonifera (red osier dogwood)
  Gaultheria shallon (salal)
  Holodiscus discolor (ocean spray)
  Ledum groenlandicum (labrador tea)
  Lonicera involucrata (black twinberry)
  Mahonia nervosa (cascade oregon grape)
  Myrica californica (california wax myrtle)
  Paxistima myrsinites (falsebox)
  Philadelphus lewisii (mock orange)
  Rhododendron macrophyllum (pacific coast rhododendron)
  Rhododendron occidentale (western azalea)
  Rosa nutkana (nootka rose)
  Rubus parviflorus (thimbleberry)
  Rubus spectabilis (salmonberry)
  Sambucus nigra subsp. cerulea (blue elderberry)
  Sambucus racemosa subsp. pubens (red elderberry)
  Spiraea douglasii subsp. douglasii (hardhack)
  Symphoricarpos albus (common snowberry)
  Vaccinium ovatum (evergreen huckleberry)
  Vaccinium parvifolium (red huckleberry)

• Drought-Tolerant Shrubs. The following shrubs can survive with little or no supplemental watering, besides rainfall, after they are established, a process that usually takes 2 to 3 years. As a general rule, these plants need good drainage in winter.

  Arbutus unedo (strawberry tree)
  Berberis darwinii (darwin's barberry)
  Ceanothus 'Julia Phelps' (california lilac)
  Ceanothus 'Victoria' (california lilac)
  Ceanothus 'Puget Blue' (california lilac)
  Choisya 'Aztec Pearl' (mexican mock orange)
  Cistus x hybridus (white rockrose)
  Cotinus 'Grace' (hybrid smoketree)
  Cotoneaster dammeri (bearberry cotoneaster)
  Elaeagnus pungens 'Maculata' (golden variegated elaeagnus)
  Hebe 'Emerald Green'
  Hebe cupressoides 'Boughton Dome' (cypress hebe)
  Hebe ochracea 'James Stirling' (whipcord hebe)
  Hebe odora 'New Zealand Gold'
  Hebe pinguifolia
  Hebe topiaria
  Ilex aquifolium 'Ferox Argentea' (hedgehog holly)
  Ilex crenata 'Convexa' (convex leaf japanese holly)
  Laurus nobilis (bay laurel)
  Mahonia nervosa (cascade oregon grape)
  Nandina domestica 'Gulf Stream' (dwarf heavenly bamboo)
  Malus toringo subsp. sargentii 'Tina' (dwarf sargent's crabapple)
  Ribes sanguineum and cultivars (flowering currant)
  Syringa vulgaris and cultivars (common lilac)
  Taxus baccata 'Fastigiata' (irish yew)
  Taxus baccata 'Repandens' (spreading english yew)
  Viburnum tinus 'Spring Bouquet' (compact laurustinus)

Resources:

Further information on shrubs and shrub-like plants may be found at the following links:

Great Plant Picks For Your Garden. Greatplantpicks.org. This site lists the Great Plant Picks for the Pacific Northwest.

The Plant List. The Saving Water Partnership. A list of plants appropriate for the temperate Pacific Northwest.

Native Shrubs. WSU Extension. A list of native shrubs, with links to information sheets on each species.

Shrub articles from the Monthly Regional Garden Column, WSU Extension Library.

• Winter Flowering Shrubs.
• Evergreen Shrubs for the Northwest.
• Protecting Shrubs from Snow Damage.
• Grow Your Own New Shrubs and Trees Now.
• Summer Care for Rhododendrons and Azaleas.

Fertilizing Landscape Trees and Shrubs. WSU Extension Bulletin EB1034.

The Trouble With Juniper. WSU Extension. A discussion of the many problems faced by junipers in Western Washington.

Low Growing Shrubs, Perennials and Groundcover for Street Side Planting. City of Seattle Arborist. This site has a very nice list of small, compact plants that may be appropriate for urban areas of Grays Harbor and Pacific Counties.