Persian Shield Plant: What you need to know

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Overview

Strobilanthes dyeriana commonly referred to as Persian shield or royal purple plant, is a species of flowering plant in the acanthus family Acanthaceae, native to Myanmar (Burma), where it grows as an evergreen perennial shrub. It gets the name Persian shield because the leaves resemble little, feudal battle shields. Persian shield plant produces 4-7 inch long, slender leaves tipped with a point. They are slightly serrated and have deep green veins with purple to silver on the entire surface of the leaf.

Persian shield usually blooms in the fall or winter. The flowers are small and blue-violet, hardly noticeable, basically insignificant against the brilliant color of the foliage for which the plant is grown. Once the plant produces spikes, floral buds arise from every node and the stems can no longer be used for propagation.

Persian shield provides seasonal color indoors in a container or it makes an eye-catching border or container plant, as well as a striking focal point in a flower bed. You can grow Persian shield outdoors in warm climates and plant them in the ground as part of a border display. In cool zones, treat the plant an annual or bring it inside at the end of summer.

Plant Profile/Facts

  • Botanical Name: Strobilanthes dyerianus
  • Common Name: Persian Shield, Royal Purple Plant, Bermuda conehead
  • Family: Acanthaceae
  • Plant Type: Evergreen Perennial
  • Mature Size: 3 to 4 feet tall
  • Sunlight Requirement: Indirect Sun, Partial Shade
  • Soil Type: Moist but well drained
  • Soil PH: Slightly acidic to neutral (5.5-7.5)
  • Temperature: 60 Degrees Fahrenheit
  • Bloom Time: Late fall or winter
  • Flower Color: Purplish-blue
  • Foliage Color: Purple
  • Hardiness Zones: 9-11
  • Native Area: Asia, Myanmar (Burma)
  • Toxicity: Mildly toxic
  • Pests: Whitefly and Aphids
  • Humidity: High Humidity

How To Grow And Care For Persian Shield plant

Soil

Persian plant prefers acidic soil with a PH between 6.0 and 6.5. However, the plant tolerates nearly any well-drained soil, including sandy, clay, acidic or alkaline soil. Well-drained soil is particularly important when the plant is young Plant it in an area with adequate drainage as too much moisture causes fungal diseases and root rot.

Sunlight

Persian shield plant can grow perfectly in a location with a partial shade; however, it prefers bright indirect light to grow healthier. Too much intense sunlight may result in leaves with a scotched, dry, streaky appearance.

Place Persian shields plant in a south-facing window where it can receive a long period of bright sunlight each day. Outdoors, it needs filtered sunlight or shifting shade. An ideal outdoor location is under a tree with an open canopy where you see moving patterns of light and shade throughout the day.

Watering

Water the plant in spring, summer and fall when the soil dries to a depth of about an inch. This is approximately the length of your index finger to the first knuckle, so sticking your finger into the soil is a convenient way to check the moisture. Water the plant deeply to saturate the root zone, until water begins coming out at the bottom.  After 1 hour, empty the saucer so that the plant isn’t standing in water. In winter, the plant enters a resting phase and doesn’t require much water.  Therefore, water sparingly during the winter months, as excess water while the plant is dormant may cause root rot and kill the plant. Allow the soil to dry out between watering. Similarly, don’t allow the soil to become completely dry as water stress may cause the leaves to discolor, wilt and drop from the plant.

Temperature

Persian shield plant grows best under average temperatures of approximately 75 degrees Fahrenheit during the day and 65 degrees Fahrenheit during the night. Heat over 85 oF can result in dropping and curling of leaves. It can also be killed by few nights of temperature below 35oF.

Humidity

Persian Shield plant requires average humidity that between 60 t0 70%. When humidity levels drop too low, the Persian shield plant transpires at a rate much quicker and this most often cause wilting and weakening of the plant. High humidity levels or soggy climate can result to fungal infections that can kill the plant.

The best way to maintain an average humidity to a Persian shield plant is to place a thin layer of rocks in a saucer and balance the pot on top and ensure fill the saucer full with water. This will help to keep the roots out of the water but the evaporation of the water provides the necessary humidity to the air. Alternatively, you can mist the leaves using rain water or distilled during low humidity periods to boost humidity.

Fertilizer

Persian shield plant benefits from a monthly feeding during spring and summer, using a balanced liquid plant fertilizer. Begin feeding in late winter or early spring when the plant begins putting out new growth and continue until late summer. Always mix the solution according to the directions on the label. To prevent burning the roots, always apply fertilizer to moist soil and don’t allow fertilizer to come in contact with the foliage. You can supplement feeding by watering with a mixture of Epsom salts and water, mixed at a ratio of 1 teaspoon salts to 1 gallon of water.

Pruning

Dip your pruning shears into a container filled with rubbing alcohol to disinfect the blades. Allow them to air dry before use. Trim off about one-third of the length of all healthy stems with the pruning shears. Select any weak, dead or diseased stems and trim them off at their point of origin on the plant. Clean up and dispose of the plant tissue.

Mulching

Mulch keeps weeds at bay and protects your Persian shield plant’s roots. It also shields the soil, keeping it moist and preventing it from washing away. Use organic mulches such as wood chips, straw, pine straw or leaf molds to mulch your Persian shield plant. Generally, spread a 1-inch layer of mulch around the plant every fall.

Overwintering

Persian shield plant can be overwintered if kept indoors. A greenhouse is preferable, but a garage is fine if the temperatures stay at around 40oF. The plant will only require few instances of watering. Bring it back outside once all the danger of frost has passed and when the night time temperature is above 45oF.

Growing Persian Shield Plant In Pot/Container

  1. Select a pot for indoor Persian shield plant that will accommodates its root ball, with about two inch to spare all around. Ceramic or clay pots are suitable especially when the plant summers outdoors, where it could blow over in the wind.
  2. Mix two parts milled peat moss, two parts perlite, one part vermiculite and a handful of bonemeal in the pot for a rich, soilless mix that allow plenty of airspace for the Persian shield growing roots.
  3. Fill the pot with the soilless mix until you reach about 1 inch from the top of the container. Moisten the mix thoroughly with water and allow the water to drain.
  4. Cut a 4-6 inch long piece from the tip of a healthy branch of this season’s growth. Use a sharp knife, cutting through the stem right under a leaf node.
  5. Dip the bottom of the stem cutting into a rooting hormone, preferably indole-3-butyric acid.
  6. Make a hole into the soilless mix and then place the stem inside the whole and fill it back, firming the sand around the stem.
  7. Persian shield has large leaves, out of which the cutting will lose moisture. Place a transparent bag over the cutting and secure it with a rubber band around the container. The bag will keep the humidity high to prevent moisture loss.
  8. Place the cutting in a room with some indirect light during the day and temperatures of between 60-65 degrees Fahrenheit ( oF)
  9. Keep an eye on the cutting daily or every other day, adding water to keep the sand constantly moist.
  10. After the Persian shield cutting shows new leaves, give it at least 5 weeks, then begin to apply a balanced houseplant fertilizer.
  11. Repot the plant annually in spring using a regular houseplant potting soil and a pot an inch larger in diameter.
  12. Once established, Persian shield plant requires supplemental watering only during periods of dry weather.

Pests And Diseases

Persian shield rarely suffers from pests or diseases and it only requires minimal maintenance to remain attractive. A healthy Persian Shield plant is sometimes bothered by scale, aphids, whiteflies and spider mites. Treat heavy infestations by spraying the plant with horticultural oil or insecticidal soap.

Common fungal diseases that can affect Persian shield plant include root and stem rot, fusarium leaf spot and leaf blight, which can be directly attributed to humid conditions and improper watering. To prevent such diseases, water at the base of the plant and avoid overhead watering. Dispose of affected plant parts to prevent spread of disease.