Plant library · Groundcovers
Isotoma fluviatilis
Blue Star Creeper is a low perennial groundcover that stays about 3 inches tall while spreading into a 1 1/2-foot-wide mat. Tiny leaves and pale blue, star-shaped flowers give it a fine-textured finish from late spring into early fall. Use it where a planting needs to read as a continuous, low layer rather than as individual clumps.
Set this groundcover at the front of borders, along bed edges, or in shallow pockets between larger perennials, where its low canopy will remain visible. It also suits rock-garden planting and narrow cracks between paving, provided the area receives only light foot traffic. Keep a clear edge beside paths so spreading stems do not soften the intended walking line, and use edging where a contained carpet is wanted.[1][2][3]
Plant on 12-inch centers for a joined cover, allowing each plant room to spread roughly 18 inches wide as the mat fills in. In a formal grid, start the outer row about 6 inches back from a path or hard edge to preserve circulation and leave the planting visible. In mixed beds, reserve the ground plane around taller plants rather than tucking it beneath dense crowns.
Give Blue Star Creeper a partially sunny position with moderate moisture, especially where its low foliage could otherwise dry quickly beside paving or stones. A moist but well-drained planting pocket is useful: choose a site that holds some moisture without remaining waterlogged. Its fine, shallow-looking carpet is easiest to maintain where irrigation can reach the entire planted strip evenly.[1][2][3]
The flowering period runs from late spring into early fall, so place it where a low scatter of pale blue flowers can show at the front of the planting. Its long seasonal occupancy makes it useful for covering exposed soil beneath taller summer growth without competing for visual height.
Avoid relying on it as a substitute for a durable path surface. Light traffic is suitable, but repeated traffic concentrates wear into a few stepping points; use pavers or a defined stepping route where people will cross often. Do not place it in a poorly drained depression, where overly wet soil can lead to root problems.[1][3]
Editorial content updated 2026-07-20.