Prostrate knotweed is a supreme indicator weed. It is the earliest germinating of all the summer annual weeds. Due to its early germination timing, knotweed is able to claim resources and invade damaged areas before other desirable grasses begin to grow. Prostrate knotweed is commonly associated with soil compaction and can be seen in gravel roadbeds, sidewalk edges, crevices, paths and other high-traffic areas (like in front of soccer goals). When knotweed germinates in March it often resembles grass and can offer some false hope that those damaged areas are spontaneously repairing themselves where the snowplow missed the sidewalk. The root system of it is extremely fine and can mine even the most compacted soils. Prostrate knotweed produces very diminutive pinkish-white flowers in the axils of the leaves and reproduces by seed.

Structure: Low-growing

Life Cycle: Annual, spread by seeds

What To Look For: Mat-like growth of stems radiating from a central taproot

Growth Period: Seedlings emerge late winter, early spring