Help with stormwater runoff: Plant an evergreen!

Evergreen plants play a vital role in our overly wet winters. They help prevent stormwater runoff and landslides by taking up water all winter long — when we have the most of it. 

Since evergreen plants do not go dormant in the winter, they can use up to 140 gallons of water a day — that’s a lot of water not overflowing our drainage systems. Their perpetual green and branching forms also help to disperse rainfall into smaller droplets, which minimize stormwater issues and erosion in the landscape.

Conifers and broadleaf evergreen shrubs also help define a garden in winter. A garden would be bleak, indeed, without green or variegated color four months out of the year.

Here are some nice evergreen plants that do well in an urban setting. 

 

Trees

•Hinoki cypress (Chamacyparis obtusa ‘Gracillis’) — A stately, narrow tree with peeling, reddish-brown bark, to 20 feet.

•Compact strawberry tree (Arbutus unedo ‘Compacta’) — Lovely, peeling bark as it ages, with white bell-shaped flowers in fall and red round fruits in summer. Grows to 6 to 8 feet tall, 5 to 6 feet wide. 

•Hollywood juniper (Juniperus chinensis’Kaizuka’) — Unique upright, bold habit. 

15 feet tall, 10 feet wide.

•Pacific waxmyrtle (Myrica californica) — Upright and shrubby, this native can have an open, loose habit. Black fruits appear in fall, and it grows to 10 to 30 feet tall over time.

•Tasmanian leatherwood (Eucryphia glutinosa) — Large, white flowers appear in summer and blooms for many weeks. Leaves take on tints of orange and red in the fall. 

The tree grows up to 25 feet and can spread up to 15 feet wide. 

Grow in a spot sheltered from hot sun and wind.

•Tanyosho pine (Pinus densiflora 'Umbraculifera') — Showy cones, mounding shape and usually multi-trunks. This tree attracts birds and is slow-growing, to 15 feet.

•Tan oak (Lithocarpus densiflorus) — Best in rich, moist soil, this can be a tree or a shrub, growing to 10 to 20 feet high. 

The acorns are oak-like, but the flowers are like those of chestnuts and provides wildlife food and nesting materials.

•Oregon myrtle (Umbellularia califoranica) — With its compact habit, Oregon myrtle looks great all year long. 

It provides wildlife food and shelter and can reach 30 feet. 

 

Shrubs

•Silk tassel bush (Garrya eliptica) — A very attractive broadleaf, evergreen shrub, especially in winter when almost glowing, silky-white tassels appear. 

It attracts beneficial insects and bees and is great for bird habitat and bird food.

•Coffeeberry (Rhamnus californica) — Red branches add interest, and fruit ripens from green to red to black on this broadleaf, evergreen shrub. 

It’s great for wildlife and can reach 15 feet in 20 years.

•Evergreen huckleberry (Vaccinium ovatum) — A native broadleaf, evergreen plant, it can reach 8 feet in shade, but it will grow well and more compact in sun. 

Glossy, green leaves, red new growth and new stems — a very handsome plant.

Birds rely on the fruit in winter.

•Mexican orange (Choisya ternate) — A broadleaf evergreen with a large, round habit, it can reach 6 to 8 feet tall and wide but can be pruned easily. 

Fragrant white flowers almost all year long if sited in full sun. 

It attracts bees.

•Camellia ‘Yuletide’ — A broadleaf evergreen, it has red flowers with yellow stamens. It can reach 4 to 6 feet.

This camellia blooms in late November and is good for hummingbirds.

•Russian olive (Elaeagnus angustifolia) — A nitrogen-fixing broadleaf, evergreen shrub that good for breaking up clay soils.

•Spaan’s dwarf (Pinus contorta ‘Spaan’s Dwarf’) — This conifer shrub may reach 3 feet high and 4 feet wide in 10 years. 

 

More information

For more evergreen plants suitable for urban gardens, visit Seattle Tilth’s website: seattletilth.org/learn/resources-1/almanac/december/plant-a-garden-for-winter-bouquets-and-wreaths.

For the effects of trees on stormwater, visit the Puget Sound Partnership’s Resource Center: www.psparchives.com/publications. 

For ideas about landscape design for wildlife, visit the Washington Department of Fish & Wildlife’s Living with Wildlife webpage: wdfw.wa.gov/living/landscaping/.

SHERI HINSHAW is an educator with Seattle Tilth’s Garden Hotline (www.seattletilth.org).