When it comes to invasive plants, there is good news and bad news. The bad news is that many invasive plants are often planted intentionally as ornamentals. These plants can escape the confines of gardens, muscle their way into local ecosystems, crowd out native plants, and destroy wildlife habitat. Despite these problems, many of these troublemakers are widely available at local and mail-order nurseries. Just because you can buy a plant, doesn’t mean you should.
The good news: There are plenty of attractive native alternatives to choose from that aren’t harmful and increase habitat for native birds, wildlife, and pollinators. And now is a great time to make the swap! Fall is a great time to start planting, especially shrubs and trees. Below, you’ll find a list of pesky ornamentals and their delightful native alternatives.
PLANT Douglas spirea, NOT purple loosestrife
Purple loosestrife’s (Lythrum salicaria) showy, upright clusters of purple flowers give it the nickname “the beautiful killer.” It is commonly planted as an ornamental species, but can quickly infest wetlands, marshes, and streams. Once mature, a single plant can produce up to 2.7 million tiny seeds annually, which spread by water, wind, wildlife, and humans. Infestations result in decreased bird habitat and can lead to erosion. Purple loosestrife is categorized as a Priority invasive species for the Tualatin SWCD.
Rather than planting purple loosestrife, plant Douglas spirea.
The Pacific Northwest native Douglas spirea (Spiraea douglasii) has similar cone-shaped flower spikes, but they are usually pink rather than purple. Its flowers and dense growth also attract a variety of wildlife, including deer, butterflies, birds, and many other small animals. Douglas spirea blooms at a similar time as purple loosestrife, July through September.
PLANT red-flowering currant, NOT butterfly bush
You can’t blame gardeners for adoring butterfly bush (Buddleia davidii). This shrub’s purple-and-orange flowers are as dazzling to the human eye as they are to pollinators. Unfortunately, butterfly bush does not always stay where we plant it. When it escapes into natural areas, it forms dense thickets, especially along riverbanks and gravel bars, which alter soil nutrients and crowd out native trees and shrubs.
In place of butterfly bush, try planting red-flowering currant.
Red-flowering currant is one of the most common currant species found in gardens and landscapes. Its drooping clusters of light to deep pink flowers are one of the first things to bloom in the Pacific Northwest, corresponding with the time mason bees are hatching from their cocoons and searching for energy-packed nectar.
PLANT wild ginger, NOT English ivy
English ivy (Hedera helix) is a plant that many people seem to love, but it’s really a plant that people should hate! While it is useful in landscaping as an evergreen groundcover, its ability to escape gardens and dominate habitats makes it sinister in parks, natural areas, and forestlands. Once it has escaped, English ivy quickly outcompetes native plants for light, nutrients, soil, and space, creating “ivy deserts” that are defunct of wildlife habitat. Ivy is particularly harmful for trees. When left unaddressed, ivy can engulf entire trees and prevent their ability to photosynthesize.
Instead of planting English ivy, plant wild ginger.
Wild ginger (Asarum caudatum) is a fast-growing ground cover with nice, big heart-shaped leaves. The plant is deer-resistant and an important source of food for local pollinators. Wild ginger grows in shade and greens early in the spring through late fall. Plant it once and it’ll grow like crazy! If you are planting in a sunnier location, we suggest planting a variety of native strawberry (Fragaria species), which is better suited to direct light.
PLANT tall Oregon grape, NOT English holly
For many people, the glossy, dark green leaves and bright red berries of English holly (Ilex aquifolium) are synonymous with the holiday season. While popular, this plant is not native to Oregon. In fact, English holly can quickly spread when planted in our region, shading out native plants and degrading our natural habitats. Additionally, its spiny leaves and berries can be toxic to humans, dogs, and cats.
Rather than planting non-native English holly, try planting tall Oregon grape.
Tall Oregon grape (Mahonia aquifolium) has similar-looking leaves and can share the same stature as English holly. This leads to observers mistaking the two species. Oregon grape is a Pacific Northwest native and can be distinguished from holly by its bright yellow flowers, which attract bees, hummingbirds, and other pollinators to the garden. Holly, on the other hand, does not typically have flowers. Another way to tell these two plants apart is by looking closely at their leaves. Holly’s leaves are alternate along the stem, whereas Oregon grape’s leaves are opposite.