Spiderwort (Tradescantia) is ambiguous for gardeners and ecologists, often marketed as a desirable perennial while simultaneously labeled a noxious weed. When spiderwort becomes a weed depends on the specific species, its growth habits, and the local ecosystem it inhabits. Understanding this dual nature is the first step in managing its presence, whether it is a welcome ornamental or an aggressive invader.
Defining Spiderwort: Ornamental or Opportunistic?
The ambiguity of spiderwort stems from the vast diversity within the genus Tradescantia, which includes approximately 85 species. Many temperate species, such as the native Tradescantia virginiana, are clump-forming perennials valued for their short-lived, three-petaled flowers in shades of blue, purple, or white. These varieties are generally considered well-behaved garden plants, forming dense, manageable upright clumps.
The genus’s reputation is largely driven by a few highly vigorous tropical species, most notably Tradescantia fluminensis (Wandering Dude). This species, native to South America, is commonly designated as an environmental weed in warm, moist climates worldwide. It is identified by fleshy, bright green leaves and small, white flowers, and its defining characteristic is a prostrate, trailing habit.
For gardeners, the issue extends beyond invasive tropical species to the sheer vigor of native types. A native spiderwort that is too enthusiastic for a small bed can become “opportunistic,” requiring frequent division to prevent it from out-competing less robust neighbors. The key distinction is that ornamental species grow in clumps, while weedy species aggressively trail and root along the ground.
Mechanisms of Aggressive Spread
Spiderwort transforms from a trailing plant into a dense, smothering weed through highly effective vegetative propagation. The primary mechanism of aggressive spread is the plant’s ability to root freely from fragments of its semi-succulent stems. Stems are brittle and break easily, and pieces as small as 10 millimeters containing a node are capable of establishing a new plant in moist soil.
This ease of fragmentation means that traditional weeding methods, like pulling or raking, often inadvertently spread the problem by scattering viable stem pieces across the garden bed. The prostrate stems of species like Tradescantia fluminensis trail along the ground, with each node capable of producing roots, creating a dense, interwoven mat. This dense mat formation then carpets the soil, effectively blocking light and preventing the germination and growth of native seedlings and other ground-level plants.
The reproductive strategy also involves seed production, though this varies by species and climate. While T. fluminensis may rarely produce viable seed in cooler regions, it does spread via seed in subtropical and tropical environments. Regardless of seed viability, the rapid re-rooting of stem fragments allows the plant to quickly colonize new areas, especially when garden waste containing fragments is improperly discarded. The plant’s high tolerance for deep shade further enables its persistence beneath tree canopies where other groundcovers fail.
Practical Control and Removal Strategies
For areas where spiderwort has become an unwanted weed, control requires a persistent, multi-faceted approach that targets the plant’s fragmentation mechanism. Manual removal is suitable for small, isolated patches, but it is absolutely necessary to collect every single piece of stem and root material. The removed plant matter should be bagged and disposed of, not composted, to prevent any remaining fragments from re-rooting.
Cultural controls focus on altering the environment to make it less hospitable. Shading is highly effective, as the plant’s biomass is drastically reduced when light levels are brought down to 5% of full sunlight. The weed can be suppressed by starving it of light, either by planting taller, dense-canopy species or by applying a very thick layer of opaque mulch. In agricultural contexts, grazing animals like cattle or chickens can consume the plant, providing a biological control option.
Chemical control is often necessary for large, dense infestations, utilizing products containing glyphosate or triclopyr. The waxy, semi-succulent nature of the leaves makes herbicide penetration difficult. Application should include an appropriate surfactant or wetting agent to ensure the chemical adheres to the leaf surface and is properly absorbed. Repeat applications will be required due to the plant’s ability to regrow from fragments that were shielded from the initial spray by the dense mat of foliage.