Physostegia, or the ‘Obedient plant’ has prolific dazzling tubular flower spikes which are arranged on distinctly square stems. This oddly named perennial is perfect for the middle of a mixed or herbaceous border in sun or partial shade.
Emerging from a dormant crown in spring, a cluster of green stems shoots upward to 90cm (30in), each clothed by 7.5cm (3in) long, narrow, waxy, dark green leaves.
Also marketed as 'Summer Snow', Physostegia 'Crown of Snow' feature pure white flowers. The sturdy clumps are topped all summer with white, snapdragon-like flowers, which can be twisted around the stem and will remain where you put them...hence, the common name.
These popular plants fill in the border in late summer, which can be an in-between time for perennials. It continues to look good well after flowering, sometimes well into November and will flower until first frosts. Best planted in fertile, reliably moist soil in full sun, the obedient plant is prized among florists and perfect as a cut flower.
The linear stems of Physostegia make them easy to arrange in a variety of designs. In addition to vegetative and botanical compositions, they are great for use in centrepieces and other types of arrangements with a formal garden style.
- Awarded the RHS Award of Garden Merit
Physostegia virginiana 'Crown of Snow' has been awarded the Royal Horticultural Society’s Award of Garden Merit (AGM).
Sowing: Sow late winter to late spring or late summer to autumn
Sow the seed thinly on the surface of lightly firmed, moist seed compost in pots, cells or trays. Just cover with a light sprinkling of compost or vermiculite. Do not exclude light as the seeds need light to germinate.
Keep at a temperature of between 20 to 25°C (70 to 75°F). Keep the compost moist but not waterlogged; water from beneath the tray. Most seeds germinate between 21 to 30 days; some may take a little longer
When large enough to handle, usually 4 to 6 weeks after germination, transplant seedlings into 7.5cm (3in) pots. At transplanting stage, the plant can be cut back, to encourage a more compact, bushy plant. Gradually acclimatise to outdoor conditions for 10 to 15 days before planting out after all risk of frost, 40cm (16in) apart. Plant in ordinary garden soil in full sun. Protect young plants from slug damage using beer-traps or environmentally-friendly slug pellets.
Divide congested colonies in early spring, otherwise this plant needs little care.
Cottage/Informal Garden, Flower Borders and Beds, Cut flowers.
Remove the foliage that would be submerged under water in vases, and cut at least 1 inch off the bottom of each stem, then place the stems into water, preferably containing a floral food solution. Allow the stems to take up water for at least two hours in a cool place before designing with them. They will benefit from having their stems recut and the flower food solution changed every other day. If this is done, they will last for approximately seven to 14 days.
Note: The flowers of Physostegia are highly sensitive to ethylene.
Physostegia virginiana is native to North America where it mainly inhabits eastern and central US but is distributed from eastern Canada down to northern Mexico. It can be found inhabiting damp, sunny places. The genus has about 15 species, available in red-violet, pink, lavender or white. It is classed in the mint family, Lamiaceae.
First introduced to gardens in 1683, it was recommended by many garden writers of the early 20th century as a companion plant in the back of the perennial border. Heirloom cultivars of this plant include 'Alba', a white form that was first offered in 1908.
The generic name of Physostegia comes from two Greek words, physa, meaning 'bladder' and stege, meaning 'covering'. The name was given because the calyx becomes inflated and covers the fruit as the seed pods develop.
The species name of virginiana refers to the origin of the plant.
The common name of Obedient Plant comes from the odd fact that the flower-heads, when moved from their usual position, stay put instead of springing back as most flowers would. The flowers are on swivels that can be bent right or left on the stem, Because of this ‘obedient habit’, it’s a fun plant for children’s gardens and is a useful feature for floral displays.
The common names of False Dragonhead and Virginia Dragon Head refer to the dragonheads of the related Dracocephalum, a genus to which the plant once belonged. In some areas it also has the common name of ‘The Lady of the Lake’.
- Awarded the RHS Award of Garden Merit
- Additional Information
Average Seed Count 40 Seeds Family Lamiaceae Genus Physostegia Species virginiana Cultivar Crown of Snow Synonym Also marketed as 'Summer Snow'. Common Name Obedient plant, The Lady of the Lake Other Common Names Obedience Plant, False Dragonhead Hardiness Hardy Perennial Flowers Mid to late Summer Height 60cm (24in) Spread 40cm (16in) Position Full sun. Soil Average to moist Time to Sow Late winter to late spring or late summer to autumn Germination 21 to 30 days