Juncus tenuis is a rhizomatous cool season perennial rush. The prominent rounded stems or culms are semi-evergreen and arranged in dense tufts. They are medium green, smooth, erect and unbranched. Linear flat leaves originate from the stem base and are much shorter than the culms.
Juncus tenuis thrives in full sun or lightly shaded sites with wet to mesic soil. Plants prosper in heavy clay and gravelly soils. They tolerate drought, flooding, moderate salinity, compacted soils and foot traffic. This rush is pest resistant and unpalatable to deer and other herbivores.