Invasive Shade-Tolerant Garden Plants in North Dakota

North Dakota's diverse landscapes, including its woodlands, river valleys, and urban shaded areas, are vulnerable to invasive plant species that thrive in low-light environments. These invasive plants can spread rapidly, outcompeting native species and disrupting local ecosystems. Understanding these plants and choosing native alternatives is essential for preserving North Dakota’s natural beauty and biodiversity.

Creeping Bellflower (Campanula rapunculoides)

List of Invasive Shade-Tolerant Garden Plants in North Dakota

1. Buckthorn (Rhamnus cathartica and Rhamnus frangula)

• Description: Deciduous shrubs or small trees with dark green leaves and small black berries. They are commonly found in wooded areas.

• Impact: Buckthorn invades forests and shaded areas, forming dense thickets that prevent native plants from growing, leading to reduced biodiversity.

• Garden Alternative: American Hazelnut (Corylus americana) - A native shrub that provides habitat and food for wildlife, thriving in shaded environments.

2. Garlic Mustard (Alliaria petiolata)

• Description: A biennial herb with heart-shaped leaves and small white flowers that emit a garlic-like odor when crushed.

• Impact: Garlic Mustard spreads rapidly in shaded woodlands, outcompeting native plants and reducing biodiversity.

• Garden Alternative: Wild Ginger (Asarum canadense) - A native ground cover with heart-shaped leaves that thrives in shaded environments and offers similar coverage without being invasive.

3. Common Tansy (Tanacetum vulgare)

• Description: A perennial herb with bright yellow button-like flowers and feathery leaves, often found in disturbed and shaded areas.

• Impact: Common Tansy forms dense stands that crowd out native plants, reducing plant diversity and affecting local ecosystems.

• Garden Alternative: Golden Alexanders (Zizia aurea) - A native perennial with yellow flowers that supports pollinators and thrives in similar habitats.

4. Japanese Barberry (Berberis thunbergii)

• Description: A thorny shrub with bright red berries and small, glossy leaves, often used for its ornamental appeal.

• Impact: Japanese Barberry forms dense thickets in shaded areas, outcompeting native plants and altering soil chemistry, which can negatively affect the surrounding ecosystem.

• Garden Alternative: Redosier Dogwood (Cornus sericea) - A native shrub with red stems and white berries that supports local wildlife and thrives in shaded areas.

5. Canada Thistle (Cirsium arvense)

• Description: A perennial herb with spiny leaves and purple flowers, often found in disturbed and shaded areas.

• Impact: Canada Thistle spreads rapidly, forming dense stands that displace native plants and reduce biodiversity.

• Garden Alternative: Wavyleaf Thistle (Cirsium undulatum) - A native thistle that supports pollinators and wildlife without invasive properties.

6. Creeping Bellflower (Campanula rapunculoides)

• Description: A perennial with tall spikes of purple, bell-shaped flowers. It spreads through rhizomes and seeds, particularly in shaded areas.

• Impact: Creeping Bellflower can aggressively take over gardens and natural areas, outcompeting native plants.

• Garden Alternative: Harebell (Campanula rotundifolia) - A native bellflower with similar purple flowers that supports pollinators and thrives in shaded environments.

7. Dame’s Rocket (Hesperis matronalis)

• Description: A biennial or short-lived perennial with fragrant purple, pink, or white flowers, often found in shaded areas.

• Impact: Dame’s Rocket spreads quickly, forming dense stands that outcompete native wildflowers in shaded woodlands and edges.

• Garden Alternative: Wild Bergamot (Monarda fistulosa) - A native perennial with lavender flowers that attract pollinators and thrive in shaded environments.

8. Yellow Toadflax (Linaria vulgaris)

• Description: A perennial herb with bright yellow, snapdragon-like flowers and narrow leaves, often found in disturbed areas.

• Impact: Yellow Toadflax spreads aggressively in shaded areas, outcompeting native plants and reducing biodiversity.

• Garden Alternative: Golden Alexanders (Zizia aurea) - A native plant with yellow flowers that supports pollinators and thrives in similar shaded environments.

9. Reed Canary Grass (Phalaris arundinacea)

• Description: A tall, perennial grass with broad green leaves, often found in wet, shaded areas.

• Impact: Reed Canary Grass spreads aggressively, forming dense stands that outcompete native vegetation, particularly in wetland habitats.

• Garden Alternative: Prairie Cordgrass (Spartina pectinata) - A native grass that provides similar height and structure in wet areas without the invasive spread.

Conclusion

Invasive shade-tolerant plants can significantly impact North Dakota’s ecosystems by outcompeting native species and altering local habitats. By selecting native, non-invasive alternatives, gardeners can help maintain ecological balance, support local wildlife, and preserve the natural beauty of North Dakota’s landscapes.

For more information and to connect with other gardening enthusiasts, join our Facebook group: Shade Gardening.