What to Plant in Wet Areas of Your Pacific Northwest Garden

Have a swampy corner of your garden that just won’t go away? It could be a lack of runoff or naturally marshy conditions. However, don’t worry about doing a major drainage project when you can just add plants that can handle those conditions.

Here are some local recommendations:

Perennials

Japanese irises (Iris ensata) are a colorful perennial that can handle wet condition, even standing water.

Another Japan native, Japanese Primrose (Primula japonica) also provides comparable bursts of color, but although it prefers moist soil it can’t handle standing water. Similarly, the Aster and Astilbe plant varieties are options for moist but well drained soils.

Local gardening guru Ciscoe Morris recommends Lobelia varieties Queen Victoria (Lobelia cardinalis) or Fan Burgandy (Lobelia speciosa). Both provide red color and attract hummingbirds and butterflies, as well as tolerating boggy areas. Just be careful: they can be toxic to pets and children if ingested.

For a large, leafy presence, Giant rhubarb (Gunnera manicata) is one of the largest perennials out there and grows up to four meters in height. It needs boggy and wet environments to prosper. If your wet area dries out, be ready to water this one!

Trees

Vine Maple (Acer circinatum) is a versatile relative of the Japanese Maple native to the Pacific Northwest. It tolerates various light levels and will grow in moist to wet areas. Moderately sized, it can provide a dash of color to the garden in fall.

Another versatile native is Cascara (Rhamnus purshiana). It can survive a variety of moisture levels, including wet soils, but does best in well drained areas. Its small flowers and berries can feed local birds.

If you want to add serious height to your yard – and have room for it – the Western Red Cedar (Thuja plicata) can reach heights of 90 feet and flourishes in moist locations. Planting one is an investment, this native tree can continue growing for as many as 300 years.

An alternative is the subspecies ‘Excelsa,’ which grows to around 20 feet tall and around 10 feet across.

Shrubs

Native to the coastal wetlands of Washington State, the Pacific Wax Myrtle (Myrica californica) is right at home in wet environments. It grows quickly, both tall and wide, making it a great choice for screening. And as an added benefit, it actually puts nitrogen and other nutrients back into the soil for other nearby plants.

Another shrub from the wet areas of the Northwest is Devil’s club (Oplopanax horridus). This one can be found in rainforests as far north as Alaska and thrives in moist environments. It has large leaves and red berries. But beware, despite its many uses in Native cultures and attraction for bears, the berries are not safe for humans to eat and the plant comes positively coated in sharp spines.

Groundcovers

For shady damp corners that aren’t too wet, you can go with the Maidenhair Fern (Adiantum pedatum). Ironically, its delicate foliage is water repellent foliage, but it prefers moist, shady areas.

Another fern for shady areas is Lady Fern (Athyrium filix-femina). This fern has a more traditional leaf shape and can handle moisture even better than the Maidenhair Fern, tolerating some seasonal standing water. In exchange, it will need to be kept wet during periods when the soil dries out.

Brunchberry (Cornus unalaschkensis) is a short, Seattle native member of the dogwood family that is also actually a perennial. It does well in a moist woodland type of environment and provides white flowers with edible berries.

An even more colorful native for wet areas is Western Skunk Cabbage (Lysichiton americanus), also known as Swamp Lantern. As the name indicates, it can survive in very wet environments such as swamps, and offers bright yellow color. However, as the name also suggests, it can be smelly when in bloom and attracts scavenging flies and beetles to pollinate it.

If you want to fill a moist and shady area quickly, False lily-of-the-valley (Maianthemum dilatatum) is a good choice. Not only does it thrive in shady, moist environments, it aggressively spreads to fill them. Monitor closely to prevent it becoming invasive.

Grasses

Slough sedge (Carex obnupta) is native to wetlands but can also form stands in muddy areas. While it prefers those heavily wet areas with a small amount of standing water, it can tolerate changes in water levels and wetness. Its root structures help to offer erosion control and it will improve water quality in wetland areas where it is planted.

Our Advice

If you want to look at redoing the planting in your yard that includes a wet area, give us a call at 206-551-9872 for a free consultation.