How to Grow Physostegia Plants

Guide to Growing Obedient Plant and False Dragonhead

Plants belonging to the hardy perennial genus Physostegia are stiff, and range in height from 30 cm to 1.2 m (1 to 4 feet).

They bloom from the middle of summer until early autumn.

Physotegia plants carry spiky tubular shaped flowers that may be pink, purple or white.

Some common names for the species include Obedient Plant and False Dragonhead.

Physostegia virginiana
Physostegia virginiana 'Vivid'; (Obedient Plant Vivid) by F. D. Richards.

Physostegia Growing and Care Guide

  • Common Names: Obedient plant, False dragonhead, Correll's false dragonhead.
  • Life Cycle: Hardy perennial.
  • Height: 12 to 72 inches (30—210 cm).
  • Native: Northern America.
  • Growing Region: Zones 3 to 9.

  • Flowers: Middle of summer through to early autumn.
  • Flower Details: Pink, purple. Sometimes streaked. Spikes of flowers. Tubular. Lipped. Opposite.
  • Foliage: Herbaceous. Lance-shaped. Toothed.

  • Sow Outside: Cover seed. Start of spring, or the beginning of autumn.
  • Sow Inside: Germination time: 2 to 4 weeks. Temperature: 60 to 75°F (15—24°C). Start off eight weeks to two months in advance. Transplant outdoors before the last frost or at the beginning of autumn. Spacing 12 to 24 inches (30—60 cm).

  • Requirements and care: Full sunlight or partial shade (drier soils only). Acidic soil pH 5—7. Moist soil, light soil, cool soil. Regular watering. May need support as can become floppy. Cut back to the ground in autumn. Rhizomatous so it is required to prune roots to prevent spreading. Propagate: by dividing in the spring.
  • Family: Lamiaceae
  • Closely Related Species: Sage, Thyme, and Oregano.
  • Miscellaneous: Can grow aggressively in rich or/and moist soils. Often used to bring late season color to borders.

How to Grow Obedient Plant and other Physostegia

Obedient Plants can be grown outdoors from seed. Sow them, and lightly cover with soil at the start of spring or autumn.

It is best to sow small species about 30 to 50 cm (12 to 20 inches) apart, and to space larger Physotegia varieties at about 60 cm (2 feet).

The soil that the plants grow in should be cool, light and slightly acidic (pH 5 to7).

Physotegia species can be grown in sunny or partially sunny parts of the garden. If growing in sunny areas ensure that the soil is kept moist.

If growing in the greenhouse first, then it should take seeds from two to four weeks to germinate. Do this at a temperature of 15 to 25 degrees centigrade (59 to 77°F).

They should be started about two months in advance. Transplant into the garden just before the last frost of spring.

Caring for Obedient Plants

Obedient plants and other Physotegia are easy to look after, but unlike their name suggests they are not obedient.

They are liable to spread, so cut the roots back hard to stop them from spreading.

The soil that they grow in should be kept moist in dry periods through watering. It is also necessary to supply mulch to the plants to ensure that the soil stays cool.

At the end of the season cut the Physostegia plant back to the ground (autumn).

I hope that you enjoyed this guide on how to grow Physostegia. You may also enjoy the following Lamiaceae family growing guides: How to grow Thyme, Agapanthus africanus, Allium caeruleum, and mint plants..