Red Twig Dogwood, recognized for its vibrant stems that offer striking winter interest, is a popular and adaptable choice for many landscapes. However, its vigorous growth often leads to a common question: is this shrub considered an invasive species? This concern stems from its tendency to spread readily within a garden environment.
Understanding Invasiveness
An “invasive species” is generally defined as a plant that is non-native to a particular ecosystem and whose introduction causes or is likely to cause environmental or economic harm, or harm to human health. These plants can outcompete native flora for resources, reducing biodiversity and disrupting natural ecosystems. Examples of truly invasive plants include species like Kudzu or Japanese Knotweed, which aggressively displace native vegetation and alter habitats.
Red Twig Dogwood (Cornus sericea), also known as Red-osier Dogwood, is native to much of North America, ranging from Alaska to Newfoundland and south through various states. Because it is native, it does not meet the ecological definition of an invasive species in these regions. While it exhibits aggressive spreading tendencies in gardens, this differs from the broader ecological harm caused by non-native invasive plants. Its vigorous growth is a natural characteristic in its native range, though some non-native cultivars might show increased aggression.
Red Twig Dogwood’s Growth Habits
The perception of Red Twig Dogwood as “invasive” by gardeners often arises from its natural growth patterns. This shrub spreads effectively through rhizomes, underground stems that extend horizontally and send up new shoots, forming dense thickets. New stems also emerge from the base of the main plant through suckering, further contributing to its expanding footprint. This vigorous growth rate enables it to colonize areas rapidly. While these spreading habits make it excellent for erosion control or naturalized areas, they can also lead to it outcompeting other plants in smaller garden spaces.
Managing Red Twig Dogwood’s Spread
Managing Red Twig Dogwood’s vigorous spreading habit is achievable with targeted strategies. Regular pruning is a primary method for control and enhances the plant’s ornamental value. Annually, in late winter or early spring, remove up to a third of the oldest stems at ground level. This practice, known as coppicing, encourages new, brightly colored stems for the best winter display. Remove any suckers emerging outside the desired plant footprint by cutting them back or digging them out.
Root barriers are an effective physical containment method in formal garden beds. Installing sturdy plastic or metal edging around the planting area can prevent rhizomatous spread. When choosing a planting site, consider areas where its spreading habit is an asset, such as large naturalized beds, along stream banks for erosion control, or in rain gardens. For mature clumps, division is an option; new plants can be created by carefully digging up rooted sections, separating them, and transplanting them.
Native Alternatives
For gardeners seeking plants with similar aesthetic appeal but different growth habits, several native alternatives offer winter interest. Winterberry holly (Ilex verticillata) is a deciduous shrub providing a stunning display of bright red berries that persist through winter, offering visual appeal and a food source for birds. Unlike Red Twig Dogwood, it does not spread aggressively.
Another option is Ninebark (Physocarpus opulifolius), a versatile shrub known for its exfoliating bark that reveals multiple layers of color in winter, providing textural interest. Ninebark cultivars offer a range of foliage colors. While not always providing vibrant stem color like dogwood, these native shrubs contribute significantly to a dynamic winter landscape and support local ecosystems without extensive spread management.