Verbena stricta aka Hoary Vervain

Verbena stricta, or hoary vervain, belongs to the verbena family. Its native range spans eastern Canada and the United States. It grows widely in the central United States. Wild plants grow in prairies, fields, thickets, and dry roadsides. Gardens grow it as a herbaceous perennial with upright clumps. Plants reach 2–4 feet [0.61–1.22 metres] tall. Their spread reaches 1.5–2 feet [0.46–0.61 metres].

White hairs cover the leaves, stems, and flower spikes. These hairs give the plant its hoary look. The square stems range from green to reddish tones. Simple leaves grow in pairs on opposite stem sides. Most leaves lack a stalk and have coarse teeth. Their shape ranges from oval to wider near the tip. Fine white hairs give them a grey-green cast. Pinnate veins branch into a network of smaller veins.

Small flowers open along narrow spikes from base to tip. The spikes reach about 0.67 feet [0.20 metres] long. Each flower has five petals and a star-like shape. Most blooms are blue-purple, though some plants have pink flowers. Only a few flowers open at any one time. NC State reports six weeks of bloom in mid-to-late summer. Chicago Botanic Garden gives a broader window, from May through October. Each flower produces four brown nutlets, with fruit present in fall.

Give this plant full sun and soil that drains well. It grows in sand, clay, and shallow rocky ground. Dry to moderately moist soil suits it best. It tolerates drought, and excess watering should be avoided. Sources place it in USDA zones 4–7 or 4–8. Growth is moderate, and routine care needs are low. Seeds offer an easy way to raise new plants. Seed-grown plants generally begin to flower in their second year. Plants can form colonies as they scatter their own seed. Remove old spikes before seeds ripen to limit unwanted spread.

Hoary vervain suits borders, rock gardens, meadows, and prairie plantings. Bees and butterflies visit its flowers. It hosts common buckeye butterfly larvae and other butterfly larvae. Birds and small mammals eat its seeds. Unwanted seedlings can make it weedy in garden beds. The supplied sources name no specific pests or diseases. Plants For A Future records leaves used for a tea-like drink. It also records past use for fever and stomach pain. These reports do not establish medical benefit. That source lists no known hazards, rather than confirmed safety.