Invasive Shade-Tolerant Garden Plants in Utah

Utah’s unique landscapes, from its mountainous regions to its shaded valleys and urban areas, are at risk from invasive plant species that thrive in low-light environments. These invasive plants can spread quickly, outcompeting native species and disrupting local ecosystems. Understanding these plants and choosing native alternatives is essential for preserving Utah’s natural beauty and biodiversity.

Russian Thistle (Salsola tragus)

List of Invasive Shade-Tolerant Garden Plants in Utah

1. Russian Olive (Elaeagnus angustifolia)

• Description: A deciduous tree or shrub with silvery leaves and small yellow flowers, often planted for its drought tolerance.

• Impact: Russian Olive invades riparian and shaded areas, forming dense stands that displace native plants and alter habitat conditions.

• Garden Alternative: Desert Willow (Chilopsis linearis) - A native tree with attractive pink flowers that supports wildlife and thrives in similar conditions.

2. Tamarisk (Tamarix spp.)

• Description: A small, shrubby tree with feathery foliage and small pink flowers, often found in riparian areas.

• Impact: Tamarisk is highly invasive, outcompeting native vegetation, lowering water tables, and reducing habitat quality in desert riparian systems.

• Garden Alternative: Goodding's Willow (Salix gooddingii) - A native willow that provides similar benefits in riparian areas without the invasive tendencies.

3. Tree of Heaven (Ailanthus altissima)

• Description: A fast-growing deciduous tree with large, pinnate leaves and small greenish flowers. It’s often planted for its rapid growth.

• Impact: Tree of Heaven spreads aggressively, forming dense stands in shaded areas that outcompete native species and alter ecosystems.

• Garden Alternative: Fremont Cottonwood (Populus fremontii) - A native tree that provides shade and supports local wildlife in riparian areas.

4. Japanese Honeysuckle (Lonicera japonica)

• Description: A vigorous vine with fragrant white to yellow flowers and dark green leaves, often planted for ornamental purposes.

• Impact: Japanese Honeysuckle forms dense mats that smother native plants, reducing biodiversity in shaded areas.

• Garden Alternative: Chaparral Honeysuckle (Lonicera interrupta) - A native vine with tubular flowers that attract hummingbirds and thrive in shaded environments.

5. Periwinkle (Vinca minor and Vinca major)

• Description: Evergreen ground covers with glossy leaves and blue or purple flowers, commonly used in shaded gardens.

• Impact: Periwinkle spreads aggressively, forming dense mats that overshadow and outcompete native ground covers, reducing biodiversity.

• Garden Alternative: Desert Marigold (Baileya multiradiata) - A native ground cover with bright yellow flowers that supports pollinators and thrives in shaded conditions.

6. 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 Banner (Thermopsis montana) - A native plant with similar yellow flowers that supports local wildlife and thrives in shaded areas.

7. Russian Thistle (Salsola tragus)

• Description: A spiny, annual plant with slender, greenish-gray leaves that often invades disturbed, shaded areas.

• Impact: Russian Thistle can spread rapidly, forming dense stands that outcompete native vegetation and alter soil conditions.

• Garden Alternative: Fourwing Saltbush (Atriplex canescens) - A native shrub that supports local ecosystems and thrives in similar environments.

8. Giant Reed (Arundo donax)

• Description: A tall, perennial grass with bamboo-like stems and feathery plumes, often found in river sides and moist, shaded areas.

• Impact: Giant Reed spreads aggressively, forming dense stands that displace native vegetation, particularly in wetland and riparian areas.

• Garden Alternative: Common Reed (Phragmites australis americanus) - A native reed that supports wetland ecosystems and provides similar coverage without the invasive impact.

9. Common Buckthorn (Rhamnus cathartica)

• Description: A deciduous shrub or small tree with dark green leaves and small black berries. Initially introduced as a hedge plant, it has since become invasive.

• Impact: Common Buckthorn invades woodlands and shaded areas, forming dense thickets that prevent native plants from growing.

• Garden Alternative: Utah Serviceberry (Amelanchier utahensis) - A native shrub that provides valuable habitat and food for wildlife, thriving in shaded environments.

Conclusion

Invasive shade-tolerant plants can significantly impact Utah’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 Utah’s landscapes.

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