Salvia scabra is an erect, herbaceous perennial, with branched stems forming a neat shrublet, 0.3 to 0.9 m tall, although usually no higher than 0.5 m. Although It does develop a woody rootstock, it cannot be thought of as a shrub. The stems are covered in dense, soft hairs without glands. The lyre-shaped leaves are lobed (lyrate-pinnatifid) with these lobes becoming more distinct with maturity. Both leaf surfaces are rough and covered in glandless hairs, with some oil globules on the underside. Petioles are up to 35 mm long.

The inflorescence is simple or branched, with up to 12 whorls of 4–6 flowers, radiating up the spikes. Floral leaves are tapering egg-shaped on the lower spike, with bracts present. Flowers are tubular, 25–40 mm long, lilac, mauve or purple. Upper corolla lip is straight. Flowering sporadically year round, peaking in summer. Calyx is also tubular, hairy and tinged mauve and barely expands when in fruit. Nutlet seeds are produced in groups of three and usually dark brown. They are moist and sticky when wet. Every plant produces hundreds of seeds and will readily self-seed, although it doesn’t appear to be weedy. Plants are long-lived for an herbaceous perennial and fruitful for more than 3 years in a garden.