Physostegia

Botanical/Latin
   Physostegia

Pronunciation
   Fy-so-stee-gee-ah

Common Name
   False Dragonhead, Obedient plant

Hardiness zone range
   3 - 9

General Comments
Easy to grow, clump forming perennials, with showy tubular flowers that are carried on stiff, four-sided, angular stems in late summer and continuing until early fall. The clumps consist of many densely arranged flowering stems that never flop. They produce spikes that are made up of flower buds that open from the bottom upwards to form upright, triangular shaped, flowering spires. The overall effect is a dramatic sea of upright, highly colorful heads, all reaching skywards above the soft green foliage.

Uses
They make a splendid display in beds and perennial borders where space is not a problem. The growth is vigorous and the clumps spread by underground rhizomes, so if the space is limited, these may not be the most appropriate plants. On the other hand, because they quickly make dense, virtually care free colonies, they play an important role in borders, island beds, naturalized areas or in mixed plantings with shrubs and conifers where bold groupings can grow and spread. They like to grow near water and will form strong, dense drifts alongside streams, on the edges of ponds, and moist woodland settings.

Hummingbirds love to visit the flowers and they make excellent cut flowers.

Light Preference
Sun to partial shade

Culture
Tough, hardy, and pest free, they are among the easiest perennials to grow. Performing well in most soil types, they grow best in rich, moist soils that contain plenty of organic matter and retain moisture in dry weather.

Since clumps have a tendency to spread, it is important to pull (or dig out) unwanted shoots to help keep the plantings in check. Older clumps will become woody, lose vigor, and have diminished flowering capacity. At this point, they should be lifted and divided, replanting the younger, outer crowns. This helps to keep them vigorous, healthy, and flowering with abundance.

Pruning: In new plantings, cut back the young growths by about half in June. This encourages stronger branched flowering shoots. After flowering, remove the old flower heads to tidy up the clumps.

Background
Physostegias are incredibly interesting. Because of the unique way that the flowers stay in place when moved, it is almost as if they are on a hinge or piece of stiff wire-move them and they stay. This is why they are commonly called "Obedient Plants". This is a useful feature when flower arranging and children find them fascinating. The botanical name comes from the Greek words Physa (a bladder) and stege (covering), which refers to the inflated part that covers the fruit capsule.

There are believed to be about 15 species, all native to North America, of which Physostegia virginiana is the most ornamental and best known. It has been cultivated since 1683, and has given rise to several good cultivars.

Splendor Suggestions
They tend to develop a thick, matted, and woody root system that can be difficult to divide in the normal way. When dividing them, try cutting out pieces with a sharp spade (like sod from a lawn), and transplant them to the new positions where they will establish and grow.

Because they are fast and reliable growers, the clumps can quickly outgrow their positions and constant division means that, sooner or later, the available spaces (and perhaps those of your friends) will be used up. When this happens, we suggest dividing the clumps about every second year, digging them up, discarding half, and replanting the other half. If the soil is regularly replenished with organic matter and nutrients, you should be able to enjoy Physostegias for many years without running out of space.

Companion Plants
Moisture lovers like Astilbes, Hostas, and Ajuga `Burgundy Glow' make good bed companions and edging plants, providing color and interest until they combine with fall flowering Anemones, Asters, and Chelones (Turtleheads).