Persuasive Invasives: Replacing Common Invasive Species in the Landscape

Persuasive Invasives: Replacing Common Invasive Species in the Landscape

Posted by Aaron Barton on Jul 10th 2022

July 11th, 2022

Persuasive Invasives: Replacing Common Invasive Species in the Landscape

While gardening is oftentimes a personal endeavor, it is important to remember our place in the greater natural community and do all we can to ensure our impact is always one of great positivity. Ensuring one’s garden is free of invasive species, no matter their perceived beauty, is one of the most important ways to maintain your garden as a beneficial space for all.

As defined by the Minnesota Department of Natural Resources, invasive species are defined as “a non-native species that: (1) causes or may cause economic or environmental harm or harm to human health; or (2) threatens or may threaten natural resources or the use of natural resources in the state.” Invasive species are often introduced unintentionally through international shipping and travel, however, they are also often introduced intentionally for their desirable appearance in the landscape. After being widely planted and embraced, their harm is later observed and it is often too late to prevent uncontrolled spread (sometimes referred to as “escaping cultivation”). Once established, invasive species harm our natural communities in many ways, including limitation of forest regeneration, displacement and depletion of native flora and fauna, and alteration of vital ecosystem processes.

Reference current state invasive species lists as part of your annual spring checklist to ensure you are making informed decisions on those exciting planned garden additions, and also to verify that any existing garden residents have not become an issue for native ecosystems in the state since they were first introduced to your garden. If you come to find one of your prized garden possessions or most sought after plants is an invasive species, don’t fret! There are countless wonderful alternatives to ensure your garden will look its best while supporting natural communities, too! Three of our most commonly planted or maintained invasive plants to avoid in Minnesota are Japanese Barberry, Winged Burning Bush, and non-native Bush Honeysuckle.

Japanese Barberry, Berberis thunbergii, is a thorny deciduous shrub native to China and Japan, introduced in the 1800s as a popular ornamental and once coveted for its unique foliage in shades of bright greens and deep reds. Prolific seed producers, Japanese Barberry produce upwards of 600 seeds per plant, viable in the soil for seven to nine years after ripening. These seeds are primarily dispersed through feeding by birds and are further spread by intentional plantings in the landscape, whereafter they quickly establish dense, impenetrable thickets in natural areas. Their deer-resistant thorny branches in turn encourage over-foraging of nearby native plants in the area, while Japanese Barberry also alter the soil composition to discourage native plant growth and encourage the further spread of Barberry.

For a similar appearance in the landscape, check out these great alternatives:

Ninebark, (Physocarpus opulifolius)
A stunning shrub native to North America with its namesake exfoliating bark for multi-season interest and showy clusters of white late spring blooms that develop into pink fruits wonderful for birds. Ninebark are available in a range of sizes depending on variety, from dwarf species of about three feet round to upwards of six to eight feet round. Physocarpus have unique maple-like foliage in a wide range of colors from the bright chartreuse of ‘Raspberry Lemonade’ to the rich burgundy of ‘Fireside,’ to the deep purple, near black leaves of ‘Diabolo.’

Smokebush/Smoketree, (Cotinus coggygria)
A small deciduous tree or shrub depending on variety with excellent color, including the vibrant light green of ‘Golden Spirit’ and the deep red of ‘Royal Purple’ and growing upwards of six to eight feet round, as well as the smaller purple ‘Lilla,’ growing four feet round. Smokebush bloom their namesake airy pink smoke-like flower panicles in early to mid-summer followed by vibrant red fall color.

Boxwood, Buxus spp.
A popular evergreen shrub typically maturing to four feet round, featuring small, waxy green leaves and a dense, compact growth habit. Excellent as a stand alone shrub or planted as part of a hedge.

Winged Burning Bush/Burning Bush, Euonymus alatus, is a fairly new addition to the state invasive species list, currently listed as a specially regulated species while undergoing a three-year production phase-out period, after which it will be listed as a restricted noxious invasive beginning January 1st, 2023. Native to eastern Russia, Korea, Japan and central China and originally introduced to North America in the mid-1800s as an ornamental species, Euonymus alatus is sought after for its distinct corky winged stems, symmetrical form, and bright scarlet red fall foliage. Like Japanese Barberry, Burning Bush produces numerous berries, spread abundantly by feeding wildlife, especially birds, whereafter they germinate and begin to form dense impenetrable thickets in nearby forests, prairies, and roadsides. The exceptionally dense canopy of Euonymus alatus in these damaging colonies shade out native vegetation and produce a monoculture of Burning Bush in place of native ecosystems, displacing and suppressing native flora and fauna alike.

For a similar appearance in the landscape, check out these great alternatives:

Serviceberry, Amelanchier canadensis
An exceptional Minnesota native deciduous tree, serviceberry are single or multi-stemmed small trees with an upright rounded form, growing 4-25’ tall and 4-15’ wide depending on variety and tolerant of shadier sites. Serviceberry blooms clusters of white flowers in late spring followed by the formation of edible purple fruits in early summer, excellent for eating fresh or used for baking or canning, and also great for birds. Amelanchier also features brilliant scarlet red and orange fall color.

Witch Alder, Fothergilla spp.
A unique and underutilized deciduous shrub, Fothergilla are shade tolerant deciduous shrubs reaching 4-10’ tall and wide depending on species and variety. Witch Alder bloom abundant white honey-scented bottlebrush flowers in mid-spring, followed by emergence of quilted blue-green foliage, and vibrant fall color ranging in color from yellows and oranges to bright reds.

Highbush Cranberry/American Cranberry Bush, Viburnum trilobum
A fantastic Minnesota native deciduous shrub, growing up to 8-12’ round with unique three-lobed green leaves, tolerant of shade, though not a true edible cranberry species. Highbush Cranberry blooms in spring, putting on a show of numerous white lacecap flower panicles that develop into clusters of its namesake cranberry-red berries in the fall, excellent for birds, alongside exceptional bright red fall color.

The non-native bush honeysuckles, encompassing Hybrid Bell’s Honeysuckle (Lonicera x bella), Morrow’s Honeysuckle (Lonicera morrowii), Tartarian Honeysuckle (Lonicera tatarica), and Amur Honeysuckle (Lonicera maackii) are large upright deciduous shrubs growing upwards of 8-12’ tall and wide. Not to be confused with the Minnesota native Dwarf Bush Honeysuckle, Diervilla lonicera, the non-native bush honeysuckles are native to Japan, Korea, and China, introduced beginning in the 1700s for use as ornamental shrubs, erosion control, and wildlife habitat, and were once desirable for their tubular, fragrant pink, sometimes white or red, early summer blooms. Spreading through bird and mammal feeding as well as by root suckering and layering, bush honeysuckles form dense thickets in woodland areas, roadsides, and disturbed areas where they outcompete native flora, tolerating nearly all site conditions from full sun to full shade and moist to sandy soils. These Lonicera species also leaf out before native vegetation, shading out native groundcover species and spring ephemerals such as Trillium, deplete soil moisture, and retain their leaves late into the fall.

For a similar appearance in the landscape, check out these great alternatives:

Northern Bush Honeysuckle, Diervilla lonicera
A crowd-favorite Minnesota native deciduous shrub that is adaptable to most soil and light conditions and exceptionally hardy. Perfect for mass plantings, hedges, and erosion control, bush honeysuckle gently spreads via root suckering over time to form excellent stands for wildlife and create gorgeous displays when planted en masse. Growing three to five feet round, Diervilla blooms clusters of tubular orange or yellow flowers in mid-summer along its arching stems that are a favorite of local pollinators, followed by attractive, rich fall color.

Trumpet Honeysuckle, Lonicera sempervirens
A beautiful herbaceous twining vine, growing up to 20 feet long and blooming numerous clusters of red-orange tubular blooms, excellent for hummingbirds, that later develop into clusters of red berries. Numerous hybrids available offer blooms in various shades of orange, pink, and purple as well.

Red Twig/Red Osier Dogwood, Cornus sericea (Cornus stolonifera)
An iconic Minnesota native deciduous shrub for multi-season interest with vibrant red bark throughout the winter, growing six to nine feet round and wonderful as a hedge or mass planting. Red Twig Dogwood are fast-growing shrubs with lush quilted green leaves and panicles of white late spring blooms, giving way to interesting light gray berries great for birds and other wildlife, and provide wonderful fall color.