Summer Grass

Summer grass is a low-growing, tufted annual grass with a sprawling or semi-erect habit. Stems root at the lower nodes where they touch soil, allowing a single plant to spread outward and form a mat over a metre or more across if left unchecked. Leaves are flat, pale to mid-green, with a fringed ligule and a somewhat hairy leaf sheath and blade base, giving the foliage a slightly soft, downy feel in many species.

The seed head is distinctive: several finger-like spikes radiate from a single point at the top of the stem, a feature shared across Digitaria species and giving rise to the common name crab grass. Seed heads appear from early to mid-summer once plants mature, and each plant can produce large numbers of seed that shed readily and persist in the soil seed bank.

Summer grass is a warm-season annual that germinates from spring once soil temperatures rise consistently, growing rapidly through summer and setting seed before dying off with the first cold weather of autumn or winter. It is common throughout turf, garden beds, nursery production areas and disturbed or bare soil across most of Australia, particularly where irrigation or summer rainfall keeps soil moist.

Because it relies entirely on seed for spread and reproduction, management focuses on preventing seed set and disrupting germination. Pre-emergent control timed ahead of spring germination is the most reliable approach, combined with maintaining dense, competitive turf or groundcover to reduce bare soil available for establishment. Seedlings and young plants can be controlled while actively growing before they set seed; established, seeding plants are harder to manage and contribute heavily to next season's population.