Invasive Shade-Tolerant Garden Plants in Alaska

Alaska's unique ecosystems, including its forests and wetlands, are under threat from several shade-tolerant garden plants that have become invasive. These plants, often introduced for landscaping, can spread rapidly in shaded environments, outcompeting native species and disrupting local habitats. Understanding these invasive species and choosing native alternatives is crucial for maintaining Alaska's natural beauty and ecological health.

List of Invasive Shade-Tolerant Garden Plants in Alaska

1. European Bird Cherry (Prunus padus)

• Description: A deciduous tree with fragrant white flowers and dark purple berries, commonly planted in gardens and urban areas.

• Impact: Invades forest understories, displacing native plants, and altering soil chemistry, negatively impacting native wildlife.

• Garden Alternative: Chokecherry (Prunus virginiana) - A native tree with similar flowers and berries that support local wildlife.

2. Reed Canarygrass (Phalaris arundinacea)

• Description: A tall, perennial grass with broad, flat leaves, often planted for erosion control in wet, shaded areas.

• Impact: Forms dense stands that outcompete native vegetation, reducing biodiversity and altering water flow in wetlands.

• Garden Alternative: Tufted Hairgrass (Deschampsia cespitosa) - A native grass that thrives in similar conditions without the invasive tendencies.

3. Orange Hawkweed (Hieracium aurantiacum)

• Description: A perennial herb with bright orange flower heads, often planted in rock gardens and as ground cover in shaded areas.

• Impact: Rapidly invades open and shaded areas, crowding out native plants, especially in alpine meadows and forest edges.

• Garden Alternative: Fireweed (Chamerion angustifolium) - A native plant with vibrant flowers that supports pollinators and fits well in garden settings.

4. White Sweetclover (Melilotus albus)

• Description: A biennial herb with fragrant white flowers, often used for soil improvement and as a forage plant in shaded areas.

• Impact: Displaces native vegetation, particularly along riverbanks, where it alters soil nitrogen levels and disrupts native plant communities.

• Garden Alternative: Lupine (Lupinus nootkatensis) - A native nitrogen-fixing plant with beautiful flowers that are ideal for similar conditions.

5. Japanese Knotweed (Fallopia japonica)

• Description: A large, herbaceous perennial with hollow stems and large, heart-shaped leaves, often planted as a fast-growing screen or for erosion control.

• Impact: Forms dense thickets that displace native vegetation, damage infrastructure, and alter natural waterways.

• Garden Alternative: Sitka Willow (Salix sitchensis) - A native shrub stabilizes soil and supports wildlife without the invasive spread.

6. Creeping Buttercup (Ranunculus repens)

• Description: A low-growing perennial with bright yellow flowers, often found in shaded, moist garden areas.

• Impact: Spreads aggressively in moist, shaded environments, crowding out native ground cover plants.

• Garden Alternative: Bunchberry (Cornus canadensis) - A native ground cover with white flowers that thrives in similar conditions without spreading uncontrollably.

7. Tansy Ragwort (Jacobaea vulgaris)

• Description: A biennial herb with yellow, daisy-like flowers, sometimes planted in wildflower gardens or left to grow in shaded, disturbed areas.

• Impact: Toxic to livestock, it invades pastures, forests, and disturbed areas, forming dense stands that displace native vegetation.

• Garden Alternative: Goldenrod (Solidago multiradiata) - A native flowering plant that supports pollinators and is safe for garden use.

Conclusion

While these plants are often used in shaded garden areas in Alaska, their invasive tendencies can cause significant ecological harm. Choosing native alternatives not only helps maintain Alaska's natural beauty but also supports local wildlife and preserves the state's unique ecosystems.