Overview and Description:
It is easy to see how Strobilanthes (pronounced (stroh-bih-LAN-theez) got its common name of Persian Shield. Its most striking feature is its colorful leaves, which have an iridescence that gives them an almost metallic look. Persian Shield is a native of Myanmar, formerly called Burma, not Persia. Persian shield is a sub-shrub that is evergreen in hot climates. In cooler climates, it is grown as an annual and is even more popular as a houseplant, because it tends to bloom during winter.
Persian shield is a non-woody sub-shrub with long pointed, variegated leaves.
- Leaves: The leaves are elliptical and grow to about 6 inches long. They are puckered and the tops are washed in purple-pink and silver. The undersides are all purple. Stems are square.
- Flowers: Pale blue tubular flowers are born on short spikes.
USDA Hardiness Zones 9–11 and up. In Zone 9 and sometimes 7 and 8, Persian Shield may die back to the ground after frost, but remain alive and regrow the following season. In Zones 10 and 11, it should remain evergreen (or "everpurple").
Persian Shield is often grown as both an outdoor annual and an indoor houseplant.
Mature Plant Size:
24--36 inches (h) x 12--15 inches (w)
If Persian shield plants bloom, it is usually in fall / winter. When grown as an annual, Persian shield may not have enough time to set buds and flower, but you won't miss them with all that colorful foliage.
It is unlikely you will find any named varieties or cultivars of Strobilanthes dyerianus.
Persian Shield planted in partial shade will pick up the light and reflect it back off its leaves. It makes a striking border plant, particularly when paired with soft gray greens or chartreuse.
In USDA Zone 10 and higher, Persian Shield can get quite bushy and makes a wonderful focal point. It may even over-winter some years in cooler climates.
Even when grown as an annual, Strobilanthes make an eye-catching addition to borders and containers. Bring a plant or two indoors, and grow as houseplants through the winter. You can always move them back outdoors, in the spring.
Growing Tips for Persian Shield:
Soil: Persian shield grows well in the neutral range of soil pH and can handle anything from about 5.5 through to 7.5.
Planting:You can start Persian shield from seed or cuttings. Seeds require somewhat warm conditions ( 55–64 degrees F. (13–18 C.) to germinate.
Plants can easily be started by softwood cuttings. Applying some bottom heat will keep them from rotting before they establish roots. Spring and early summer are the best times to take cuttings.
Persian Shield prefers moist soil and some shade during the hottest parts of the summer. The less water it gets, the more shade it will need. Cold water may spot the leaves.
Since Persian Shield is grown for its foliage and the flowers are not particularly showy, many gardeners like to pinch back the leaves, to create a fuller plant.
If left to grow on its own, it can get tall, leggy and floppy.
The exception would be immediately after flowering. The leaves may look sad at this point, but that is because the plant has gone dormant for the remainder of the winter. Resist the temptation to pinch at this point, to avoid disturbing dormancy. Resume pinching when the plant starts growing in earnest, in the spring.
If grown in rich soil with plenty of moisture, Persian Shield should only need light feeding at the start of the season and again about mid-way through the summer.
Growing Persian Shield as a House Plant:
- Indoors, Persian Shield needs bright light, to keep its color, and temperatures above 60º F (15.6ºC).
- Make sure it has humid conditions. Dry air will cause the leaves to dry and drop. Misting daily is recommended, but be sure to use soft water. Chlorine will damage the leaves.
Pests & Problems:
Aphids and Whiteflies can become pests, especially when the plants are drought stressed.
Strobilanthes is not usually susceptible to fungus disease or other problems with the foliage, except water stress.