Physostegia virginiana (Obedient Plant)

Overview

• Scientific name: Physostegia virginiana

• Common names: Obedient Plant, False Dragonhead

• Family: Lamiaceae (Mint family)

• Native range: Widespread across eastern and central North America — from the Great Plains to the Atlantic, and from southern Canada to northern Mexico.

• Habit: Herbaceous perennial

• Height: 2–4 feet tall, spreads aggressively via rhizomes

• Flowering period: Late summer to early fall (July–September)

• Flower color: Pink to purplish-pink (occasionally white)

Ecological Value

Pollinator Support

• Bees: Strongly attracts long-tongued bees (e.g., Bombus spp., honeybees, large solitary bees).

• Butterflies: Nectar source for monarchs (Danaus plexippus), swallowtails (Papilio spp.), sulphurs, and skippers.

• Hummingbirds: The tubular flowers are well-adapted for ruby-throated hummingbirds (Archilochus colubris).

• Moths: Some sphinx moths also visit for nectar in evening hours.

Specialist Relationships

• While not known as a larval host plant, it provides late-season nectar when other native flowers are declining — crucial for migrating monarchs and late-foraging bees.

Birds & Other Wildlife

• Birds rarely eat the seeds, but finches and small songbirds may occasionally forage on them in winter.

• Dense growth can provide cover for small insects and microhabitats in prairie and wet meadow ecosystems.

Habitat Role

• Found in moist prairies, streambanks, open wood edges, and wet meadows.

• Functions as a nectar bridge between midsummer and fall bloom periods, important in succession plantings.

Growth Characteristics

• Light: Full sun to light partial shade (best bloom in sun).

• Soil: Prefers moist, moderately rich soils but tolerates clay or sandy loam.

• Moisture: Likes consistent moisture; tolerates occasional drought once established.

• Aggressiveness: Spreads via rhizomes; can form colonies — good for naturalistic plantings but may need containment in formal gardens.

Growing from Seed

Seed Collection

• Collect seeds in late fall (October–November) once seed capsules turn brown and begin to split.

• Seeds are small, dark brown, and drop easily when mature.

Seed Treatment

• Cold stratification is required (mimics winter conditions):

  • Moist stratify for 30–60 days at 34–40°F (refrigerator method: mix with damp sand/vermiculite in a sealed bag).

  • Alternatively, sow outdoors in fall for natural stratification.

Sowing

• Outdoor fall sowing: Scatter on prepared soil in fall; lightly press or cover with ⅛ inch soil.

• Indoor spring sowing: After stratification, sow 6–8 weeks before last frost in flats; keep moist until germination (1–3 weeks).

• Light requirement: Seeds germinate best with light exposure — avoid heavy covering.

Transplanting

• Transplant when seedlings have 2–3 sets of true leaves; space 18–24 inches apart.

• Plants establish quickly and may bloom in their second year.

Management in Gardens

• Control spread: Install root barriers or regularly divide clumps every 2–3 years.

• Companion plants: Works well with other moisture-loving late-bloomers like Eupatorium perfoliatum (boneset), Helenium autumnale (sneezeweed), and Aster novae-angliae (New England aster).

• Deer resistance: Moderately deer-resistant (mint family aromatic foliage).

Why Plant It?

• Extended bloom late in the season, filling a nectar gap.

• Supports multiple pollinator guilds — bees, butterflies, hummingbirds.

• Thrives in rain gardens and prairie restorations, especially moist lowlands.

• Low-maintenance once established and tolerant of various soils.