Physostegia, commonly known as Obedient Plant or False Dragonhead

What Makes Physostegia So Special?

Physostegia is special for its unique, snapdragon-like flowers that are arranged in dense, vertical spikes. The most distinctive feature, and the source of the common name "Obedient Plant," is that you can gently push the individual flowers to a different position on the spike, and they will stay there! This playful characteristic, combined with the long bloom time and attractiveness to pollinators, makes it a fun and rewarding plant to grow.

Description

• Growth Habit: Upright, clump-forming perennial. It spreads by rhizomes, but the aggressiveness of the spread varies depending on the cultivar and growing conditions.
• Height: Typically, 2-4 feet tall, sometimes taller.
• Foliage: Lance-shaped, toothed leaves that are arranged oppositely on the stems. The foliage is usually a medium green.
• Flowers: Tubular, two-lipped flowers that resemble snapdragons. They are arranged in dense, vertical spikes. Colors range from pink and purple to white.

Details Gardeners Care About

• Sunlight: Full sun to part shade. It flowers best in full sun, but it can tolerate some shade.
• Soil: Prefers moist, well-drained soil that is rich in organic matter. It can tolerate a wide range of soil types, including clay.
• Water: Needs regular watering, especially during dry periods. It is not particularly drought-tolerant.
• Hardiness: Generally hardy in USDA zones 3-9.
• Deer Resistance: Generally considered deer-resistant.
• Attracts Pollinators: A favorite of bees, butterflies, and hummingbirds.
• Spreading Habit: Can be an aggressive spreader in ideal conditions, especially the species Physostegia virginiana. Choose cultivars carefully and be prepared to manage its spread.

Native Habitat

Physostegia virginiana, the most common species in cultivation, is native to:

• North America (primarily the eastern and central United States)

It is often found in:

• Moist meadows
• Wetlands
• Along streams and rivers
• Open woodlands

Landscaping Design Tips

• Borders: Excellent for the middle or back of the border, providing vertical interest and late-season color.
• Cottage Gardens: A natural fit for cottage gardens, with its informal habit and charming flowers.
• Butterfly Gardens: Plant it to attract butterflies and hummingbirds.
• Cutting Gardens: The flower spikes are excellent for cutting and last well in vases.
• Mass Plantings: Can be planted in groups for a dramatic display.
• Naturalizing: Can be allowed to naturalize in moist meadows or informal areas (be mindful of its spreading habit).
• Water Gardens: Suitable for planting near ponds or in boggy areas.

Planting and Care

• Planting Time: Spring or fall.
• Spacing: Space plants 18-24 inches apart, depending on the cultivar and desired effect.
• Planting Depth: Plant at the same depth they were growing in their nursery pots.
• Watering: Water thoroughly after planting and keep the soil consistently moist, especially during the first growing season.
• Mulching: A layer of mulch helps retain moisture and suppress weeds.
• Fertilizing: Fertilize in spring with a balanced fertilizer or compost.
• Deadheading: Deadheading (removing spent flower spikes) can encourage continued blooming and prevent self-seeding (if desired).
• Pruning: Cut back the stems to the ground in late fall or early spring.
• Division: Divide clumps every 3-4 years in spring or fall to rejuvenate the plants and control their spread.
• Staking: Taller cultivars can benefit from staking.

Taxonomy (Simplified)

• Genus: Physostegia
• Species: virginiana (most common in cultivation)
• Family: Lamiaceae (Mint family – square stems!)

Morphology (Simplified)

• Stems: Square, upright stems (characteristic of the mint family).
• Leaves: Opposite, lance-shaped, toothed.
• Flowers: Tubular, two-lipped, arranged in dense, vertical spikes (racemes). The individual flowers can be repositioned and will stay in place.
• Roots: Fibrous root system with rhizomes (underground stems) that allow it to spread.

Other Insights

• "Obedient" Flowers: The unique ability to reposition the flowers is a fun and engaging characteristic of this plant.
• Spreading Habit: Be aware of its potential to spread, especially in moist, rich soil. Choose less aggressive cultivars if this is a concern. 'Miss Manners' is a well-behaved cultivar that is much less aggressive.
• Late Bloom Time: The late-summer to fall bloom time is a valuable asset, providing color when many other perennials are finished blooming.
• Cut Flowers: Long lasting cut flower.

In summary, Physostegia (Obedient Plant) is a rewarding perennial that offers vertical interest, late-season color, and a unique, interactive feature with its "obedient" flowers. It is a favorite of pollinators and a great addition to cottage gardens, borders, and other sunny or partly shady spots. However, be mindful of its potential to spread, especially in ideal conditions, and choose cultivars accordingly. With proper management, it can be a beautiful and engaging addition to the garden.