Creeping phlox (Phlox subulata) is a popular ground cover plant, known for its vibrant spring blooms. Chosen for its aesthetic appeal and ease of care, a common concern revolves around its spreading nature and whether it becomes problematic in gardens or natural environments.
Defining Plant Invasiveness
In horticulture, distinguishing between an “aggressive” and “invasive” plant is important. An aggressive plant spreads vigorously within a garden, potentially outcompeting less robust neighboring plants. While sometimes undesirable, this behavior remains confined to cultivated areas.
An invasive plant, conversely, is a non-native species introduced to an ecosystem causing environmental or economic harm. They establish in native plant communities, outcompeting local flora, altering habitats, or disrupting ecological balance. Unlike aggressive plants, invasive species spread beyond garden boundaries into natural landscapes, threatening biodiversity.
Creeping Phlox Growth Habits and Spread
Creeping phlox is a low-growing, mat-forming perennial with dense growth. It spreads through above-ground leafy stems called stolons, which root as they grow, quickly covering an area. This habit forms a thick carpet of foliage and flowers.
Typically reaching 4 to 6 inches tall, creeping phlox spreads vigorously, often up to 2 feet wide. This rapid expansion fills spaces and suppresses weeds effectively in gardens. Its ability to spread makes it a robust choice for ground cover, requiring understanding of its growth for management.
Is Creeping Phlox Truly Invasive?
While a vigorous garden spreader, creeping phlox is generally not ecologically invasive. As a native to the eastern and central United States, it co-evolved with local ecosystems and typically does not escape cultivation to outcompete native plants.
Its aggressive growth can overtake less vigorous species in mixed borders. However, this differs from ecological harm caused by non-native invasive species. In rare instances, particularly in disturbed natural areas adjacent to gardens, its spread might become noticeable, but it is classified as “minimally invasive” at most.
Managing Creeping Phlox Spread
Managing creeping phlox spread is straightforward and maintains garden aesthetics. Regular pruning after blooming (late spring or early summer) controls its size and promotes denser foliage. Cutting back stems by one-third to one-half after flowering encourages new growth and can lead to a second, less vigorous bloom.
Dividing overgrown clumps every two to three years also manages spread and rejuvenates mature plants. This involves digging up the plant, cutting the root ball, and replanting divisions. Choosing appropriate planting locations, like rock gardens or slopes where spreading is desirable, minimizes intervention.
Benefits of Growing Creeping Phlox
Despite its vigorous growth, creeping phlox offers numerous benefits. It provides a vibrant, carpet-like display of star-shaped flowers in early spring, available in pink, purple, white, and blue. Its dense foliage suppresses weeds and prevents soil erosion on slopes and banks. This low-maintenance perennial is drought-tolerant once established and attracts pollinators like butterflies and hummingbirds.