Salvia argentea aka Silver Sage

Salvia argentea, or silver sage, belongs to the mint family. It comes from southern Europe and northern Africa around the Mediterranean. This clump-forming plant grows as a biennial or short-lived perennial. It makes a low leaf rosette in its first year. Flower stems rise above the leaves in the second year. Plants often die once they have flowered and set seed.

Gardeners grow silver sage mainly for its soft, woolly leaves. The foliage mound reaches about 1 foot [0.3 metres] tall. It can spread to about 1.7 feet [0.5 metres] wide. Flower stems reach 2–3 feet [0.6–0.9 metres]. RHS gives an upper height of 3.3 feet [1 metre]. Broad, oval leaves have wrinkles and rounded teeth along their edges. They reach about 0.7 feet [0.2 metres] long. New spring leaves look silver-white, then turn gray or gray-green. The plant keeps some leaves through winter. Its stems have a square cross-section and lack scent.

Small, hooded, tube-shaped flowers grow in whorls on branched stems. They are white, sometimes with a pink blush. Chicago Botanic Garden records bloom from May through August. NC State places flowering in early summer; RHS notes late summer. The fruit splits into tiny brown nutlets. Plants can seed themselves when gardeners leave the flowers in place. Removing flower stalks before bloom may help plants live longer. Gardeners can also raise plants from spring-sown seed.

Give silver sage full sun and soil that drains well. It also tolerates light partial shade. Light, sandy or gravelly soil suits it well. Sources also list loam, chalk, and well-drained clay. It accepts acid, neutral, and alkaline soils. It tolerates drought, though moist soil with good drainage suits it. Wet winter soil can cause trouble. Heat and summer rain can also weaken plants. Published hardiness ranges cover USDA zones 5–8 and UK rating H5.

Use it along borders, beside walls, or in pots. Its pale leaves suit night gardens, rock gardens, and cottage gardens. Their soft surface also suits sensory and children's gardens. Deer tend to leave it alone. Slugs, snails, leafhoppers, and rosemary beetles may attack it. Possible diseases include root and stem rots, mildew, rust, and leaf spot. RHS also lists verticillium wilt and, rarely, honey fungus.