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 degrade wildlife habitat and property values. Despite these problems, many of these troublemakers are widely available at local and mail-order nurseries. If a new plant catches your eye, do a quick search in our Weed & Pest Directory to ensure it’s not invasive.
The good news is, 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 serviceberry, NOT English hawthorn
English hawthorn (Crataegus monogyna) is similar to invasive Himalayan blackberry. It creates a thorn in landowners and land managers’ sides! Its dense thicket of thorns is challenging to treat and makes it difficult for animals to access food and water. It has dark-red berries and typically grows in forest understories, along roadsides, and vacant lots. This plant can also hybridize with native Douglas hawthorn (Crataegus douglasii) to create a more competitive species that can threaten Oregon white oak (Quercus garryana) habitat and hinder oak woodlands.
Rather than planting English hawthorn, plant serviceberry.
Serviceberry (Amelanchier alnifolia) is a common native shrub species that grows in full sun or partial shade and can tolerate dry, moist, or wet soil. In mid-spring to early summer, it bears white fragrant flowers, which change to a dark blue color in the fall and winter. This plant is great for pollinators like bees and butterflies as well as animals looking for a tasty snack.
PLANT red osier dogwood, NOT woody knotweed
There are several species of woody knotweeds (Polygonum species), but all have the same destructive impact. These plants thrive in riparian areas such as riverbanks, wetlands, and disturbed areas like roadsides, and yards. They form hollow stems, similar to bamboo, that can grow to be 10 feet tall in one season! Knotweed spreads easily by broken stem fragments that can be dispersed by moving water, digging, composting, and mowing. Knotweed damages infrastructure, outcompetes native plants, and increases erosion, which affects fish habitat and property values. It is illegal to sell and buy knotweed in nurseries or in a secondary market throughout Oregon.
In place of woody knotweed, try planting red osier dogwood.
Red osier dogwood (Cornus sericea ssp. occidentalis) is perfect for backyards and community gardens, and it is also frequently planted in wetland and streamside habitats as it thrives in damp soil. This is a popular ornamental shrub with red-colored stems, vibrant white flowers in the spring, and red and purple leaves in the fall. It also provides food sources for pollinators, hummingbirds, birds, and mammals.
PLANT rhododendron, NOT spurge laurel
Spurge laurel (Daphne laureola) is a common ornamental plant that escapes gardens and spreads into forests. It is a small shrub with dark, shiny, evergreen leaves. Its flowers are light green in winter and produce small, blue-black berries by late spring. Not only does it out compete native plants, but it is also toxic to humans and animals! Make sure to wear gloves if you are handling this plant and keep animals and children at a safe distance.
Instead of planting spurge laurel, plant rhododendron.
Western rhododendron (Rhododendron macrophyllum) is a favorite for gardeners and landscapers in the Pacific Northwest. It tolerates many soil types and moisture conditions including dry shady locations. Rhododendrons have dazzling pink or white flowers that are great for attracting pollinators. While this plant can grow up to 20 feet tall, they are very slow growing and can be kept smaller if preferred.