- Family (English) Vervain
- Family (botanic) Verbenaceae
- Tree or plant type Perennial
- Native locale Chicago area, Illinois, North America
- Size range Large plant (more than 24 inches)
- Light exposure Full sun (6 hrs direct light daily)
- Hardiness zones Zone 4, Zone 5 (Northern Illinois), Zone 6 (City of Chicago), Zone 7
- Soil preference Moist, well-drained soil
- Tolerances Dry sites, Occasional drought
- Season of interest midsummer, late summer, early fall
- Flower color and fragrance Purple
- Shape or form Narrow, Upright
- Growth rate Moderate
- Wildlife Insect pollinators
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More information
Hoary vervain produces small, densely packed, bluish-purple flowers from late spring to early fall. Hoary vervain is tall, adding structure to drought-tolerant gardens, pollinator gardens, native gardens, naturalized meadows, or woodlands. It prefers to grow in moist to dry, well-drained soils with full sunlight. This species is native to the Chicago region according to Swink and Wilhelm’s Plants of the Chicago Region and current research.
Size and method of spreading:
At maturity, hoary vervain is between 2 to 4 feet tall and 1 ½ to 2 feet wide. It spreads by self-seeding.
Native geographic location and habitat: (include C-value if appropriate)
Hoary vervain has a native range that includes the majority of the continental United States. C Value: 4.
Attracts birds or pollinators:
Hoary vervain attracts bees, butterflies, flies, skippers, songbirds, and wasps.
Leaf description:
The leaves of hoary vervain are up to 4 inches long and 3 inches wide (ovate or obovate) and mostly stalkless or have short, winged stalks (petioles). They are yellowish-green to medium green and have prominent veins. The edges of the leaves are coarsely toothed (serrate margins), and the base of the leaves are rounded while the tips are tapered to a point. Both leaf surfaces are covered with hair (pubescence). This gives the leaves the hoary, or gray-white, look.
Flower description:
Hoary vervain flowers are tiny, bluish-purple, and densely packed onto pencil-like spikes. The spikes are up to 8 inches long and are branched into small, upright groups (panicles). Only a few flowers open at a time, and they mature upward from the bottom. Each flower is up to one-half of an inch in diameter and has a tubular petallike structure (corolla) that divides into five spreading lobes at the top. The top four lobes are rounded, and the bottommost lobe is notched at the tip. Surrounding the base of the corolla is a leaflike, green to purplish-red, tubular structure (calyx) that divides into five sharply pointed, hairy lobes.
Fruit description:
The fruit of hoary vervain is small, brown, dry, four parted, and does not open to release the seeds (schizocarps). The calyx from the flowers remains around the fruit as it matures (persistent calyx).
Plant Care:
Medium moisture to dry, well-drained soils in full sun are preferred by hoary vervain. Do not overwater this species. Hoary vervain is a low-maintenance perennial, but deadheading can prevent self-seeding.
List of pests, diseases, and tolerances:
Hoary vervain is not susceptible to major issues with pests and diseases. It is drought tolerant, but may lose some lower leaves in dry weather. This species is deer and rabbit resistant.
