Persian shield (Strobilanthes dyerianus) is a tender, perennial shrub known for its iridescent purple foliage. In its native Myanmar, it is typically found growing in the understory of tropical and subtropical forests. It prefers warm, humid conditions and rich, well-draining soil.
The lance-shaped leaves are dark green with deep purple hues. Spikes of lilac, funnel-shaped flowers emerge in the fall or winter. Persian shield grows as an evergreen in warm climates and an herbaceous perennial in temperate climates. In colder regions, it is commonly grown as a houseplant or as an annual.
| Scientific Name | Strobilanthes dyerianus |
| Common Names | Persian Shield, Royal Purple Plant |
| Plant Type | Tender perennial shrub |
| Family | Acanthaceae |
| Genus | Strobilanthes |
| Origin | Myanmar, Southeast Asia |
| Size | Up to 3-4’ tall, 3’ wide |
| USDA Hardiness Zones | 8-11 |
| Propagation Methods | Softwood cuttings, seed |
| Climate | Subtropical to tropical |
| Soil Type | Fertile, moist |
| Sun Exposure | Partial sun |
Persian Shield Care
Persian Shield Light Requirements
Provide several hours of bright light each day and protect from intense, direct sunlight. Outdoors, grow in a location that receives morning sun and afternoon shade. Indoors, grow next to an east- or south-facing window and use a sheer curtain to provide filtered light. In low light conditions, growth will become leggy and the purple coloring will fade. Too much intense light can also cause fading and bleaching.
Soil
The soil should be rich, moist, and well-draining. For container plants, combine two parts regular potting mix with one part peat moss or coconut coir. Incorporate organic matter into the soil before planting outdoors to improve fertility and water retention.
Water
Keep the soil moist but avoid waterlogging. For potted plants, water once the top 1 to 2 inches of soil is dry. Ensure the pot has good drainage and allow excess water to drain away. For outdoor plants, maintain evenly moist soil. Watering may be once a week or more regularly in hot weather. Mulch around the roots of outdoor plants to help retain moisture. Persian shield plants will wilt when they are too dry but will recover quickly once hydrated. Plants in shadier locations will require less water.
Humidity and Temperature
Persian shield is adapted to grow in warm, humid conditions. Place in a humid location such as a bathroom or kitchen. Mist indoor plants regularly with luke-warm, filtered water. Maintain an optimum temperature range of 65 °F to 75 °F. In low humidity, leaves may dry or eventually drop.
Fertilization
Strobilanthes dyerianus prefers nutrient-rich soils. For potted plants, feed with a diluted fertilizer once every 3 to 4 weeks during the spring and summer. Outdoors, apply a slow-release fertilizer in early spring to support the growing season. Fertilize again in mid-summer.
Tip: Choose a nitrogen-rich fertilizer to encourage lush foliage.
Pruning
Prune in mid to late spring to manage size and maintain bushy foliage. Remove any dead or dying branches and cut back leggy stems. Pinch ends of young shoots to encourage bushy growth.
- Use a clean, sharp pair of scissors. Sterilize tools with rubbing alcohol before and after pruning.
- Take care not to remove more than a third of the plant.
Note: The Persian shield plant grows quickly and will need to be pruned to maintain a suitable size when growing indoors. Prune the roots of older plants when repotting to help manage growth.
Flowering
Persian shield is most likely to flower when grown outdoors in tropical or subtropical climates (USDA zones 9-11). The blooming period is in the fall or early winter. Consider that Persian shield is grown for its foliage rather than its flowers. Pinching back growing tips will encourage bushy growth over flowering.
Note: The plant may appear to lose vigor or vibrancy after flowering. Wait until the spring to prune away old or withered branches.
Persian Shield Propagation
Propagate Strobilanthes dyerianus from cuttings or by seed. Cuttings will root and establish relatively easily. Growing from seed is a slower process.
Softwood Cuttings
Take cuttings in the spring or summer when the plant is actively growing.
- Select a young, healthy, non-flowering stem.
- Using sharp, sterilized scissors, cut a 3 to 4-inch length. Remove the lower leaves.
- Plant the cutting into moist peat moss, coconut coir, or commercial rooting mix.
- Cover the pot with a clear plastic bag to maintain humidity. Remove the bag daily to ensure good ventilation.
- Place in bright filtered light and keep the soil moist.
- Roots should develop within several weeks. Transplant into a larger container.
Seed
Propagate from seed in early spring.
- Fill a tray with seedling potting mix. Water lightly.
- Sow seeds and press lightly into the surface of the soil. Take care not to bury them.
- Cover with a clear plastic film or lid.
- Place in bright filtered light and keep warm (70 °F to 75 °F). Mist the soil regularly to maintain moisture.
- Persian shield seeds may take 1 to 4 weeks to germinate. Remove the plastic cover.
- When the seedlings have developed a pair of true leaves, transplant them into individual pots.
Repotting
Repot young plants every year in the spring. Once the plant reaches maturity, repot every two years. Choose a slightly larger pot that has good drainage. Cut back any old, leggy, or woody growth. Prune the roots of larger plants to control size.
Overwintering
Reduce watering frequency through the winter but avoid overly dry conditions. In temperate climates, bring container plants indoors during the colder months or grow as annuals.
Common Problems
- Drying leaves and leaf drop: May be a symptom of low humidity. Maintain consistently warm, humid conditions. Place indoor plants in a humid location such as a bathroom or kitchen.
- Wilting foliage: Caused by underwatering. Check soil moisture before watering well. Maintain consistently moist soil.
- Faded coloring and leggy growth: Caused by insufficient light. Place in a location that receives bright, indirect light. Cut back leggy stems to encourage compact, bushy growth. Propagate new plants from the stem cuttings.
- Faded coloring, leaf curl, and wilting: Caused by intense sunlight. Leaves may also develop brown or scorched edges and tips. Move the plant to a location that receives morning sun and afternoon shade. Provide filtered light using a sheer curtain.
Note: The foliage will naturally fade and lose vibrancy over time as the plant matures.
Pests
The Persian shield plant is relatively resistant to most pests but may encounter aphids, whiteflies, or spider mites when grown indoors. The plant is more susceptible to pests when it is experiencing stress caused by underwatering or inadequate humidity. Isolate infested plants and treat them with a mild insecticidal soap or neem oil.
Diseases
Persian shield is generally disease-free when grown in the correct conditions.
