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Foliage

Persian Shield: Caring For Strobilanthes Dyeriana


13 min read

Are you into purple plants? Do you like the notion of a plant that is low-maintenance, rarely has any pest or disease issues, and which will brighten up a room? In that case, consider the Persian shield plant!

This tropical plant, which originates in southeast Asia, makes a fantastic plant whether indoors or out. The leaves are nearly iridescent or metallic purple when it’s in full color, edged in a deep, dark green, and it can really liven up a room!

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Persian Shield Overview

Persian Shield Quick Care
Persian shield quick care illustration by Seb Westcott.
Common NamePersian shield plant, royal purple plant
Scientific NameStrobilanthes dyeriana
FamilyAcanthaceae
LightFull sun to partial shade
WaterKeep soil evenly moist; water when top couple inches of soil are dry
Temperature60 degrees Fahrenheit and above
HumidityHigh humidity preferred
SoilRich, well-drained soil with lots of plant matter, pH range 5.5-7.5
FertilizerDiluted half-strength balanced liquid fertilizer every 2 weeks in spring/summer, less in fall, none in winter
PestsSpider mites, fungus gnats
DiseasesNone are problems for this plant

 All About Persian Shield

Persian shield leaves
Persian shield leaves. Source: McAli333

Strobilanthes dyerianus, the Persian shield plant, is sometimes known as the royal purple plant. Unlike many other plants, there aren’t any cultivar variations with additional names, as it’s all the same basic plant. Native to Myanmar (formerly known as Burma), Persian shield comes from Southeast Asia.

This lush tropical has lance-shaped, dark green leaves that flush to a brilliant purple. A silvery, iridescent sheen can sometimes coat the purple flush, making the purple look metallic or iridescent. Each of the Persian shield leaves can grow to reach 7 inches in length and up to 3 inches wide.

Persian shield often grows to be three to four feet tall, and two to three feet in width. They’re primarily grown as potted plants for those brilliant purple-flushed leaves, but do produce some tiny purple or white flowers in the winter months in zones 10-11 or when overwintered indoors.

The flower is blue-violet in coloration,  tiny and funnel-shaped. They’re often lost against the stunning foliage, and many growers pinch off flower stalks when they appear.

While people often grow Persian shield as an annual, it can be grown as a perennial if you have the right conditions. Rainforest plants such as this purple and green plant prefer a humid environment and warm temperatures and seldom tolerate cold well.

As the color of the plant can fade with age as well, most grow this plant as an annual. Alternately, you can heavily cut it back to encourage new growth and color.

Persian Shield Care

Persian shield plant
A larger S. dyerianus specimen. Source: The McGee

Being a tropical plant, Persian shield can occasionally be a little picky, so it’s essential to know the best conditions to grow them in. Here’s a short checklist of what you need to do when you grow Persian shield.

Light and Temperature

Persian shield can handle full sun to partial shade, but if you’re at all in doubt, opt for growing Persian shield in slightly shadier conditions. As these often grow under the cover of trees, dappled sunlight is just fine.

People in hot desert environments where the sun is blindingly hot should also plan on going for partial shade conditions when growing this outdoors. At the very least, ensuring the plant has afternoon shade during the hottest part of the day is wise.

If your Persian shield plant is getting too much sunlight, it won’t develop that vibrant, iridescent purple foliage, and you should move it somewhere shadier.

Growing your Persian shield as a houseplant? If so, you’ll need a grow light or a sunny window to ensure your plant’s catching enough rays. You’ll also want to turn the plant regularly to ensure it doesn’t become leggy as it reaches towards the light.

You can grow Persian shield outdoors in zones 8-11 but it does best in zones 10-11 as it more closely resembles the plant’s natural habitat. Overwintering should only be done in zones 10-11 or on warm years in zone 9. Those in the colder climates of zone 8 should plan on having it indoors during the cold months.

Temperatures for the Persian shield plant should remain above 60 degrees to maintain that brilliant coloration. While light frosts will cause the plant to die back, it may recover in the spring if it never got to hard frosts or freezing conditions.

Water and Humidity

Your royal purple plant will like having consistent, even moisture in its soil. Water when the top couple of inches of soil are dry, which indoors is often twice a week (and may be more often outside).

Indoor growers need to monitor their soil moisture regularly, especially throughout the winter months when we’re all running our heaters.

Persian shield does like to grow outside as well, but when doing that, be sure that the soil also remains consistently moist, and add mulch to keep the soil moisture from evaporating.

This is a high-humidity plant — it likes damp air! To increase that, place your pot on top of a tray of pebbles and water. The water will evaporate and provide more humid conditions. Outdoor growers can set bowls of water next to their plants for a similar effect.

Soil

Closeup of a leaf
A closeup of a leaf. Source: monteregina

As a tropical plant, your Strobilanthes dyerianus is naturally accustomed to rich soil filled with plenty of plant matter that retains water. To simulate this, you’ll want to opt for a rich and well-drained soil. When you’re growing Persian shield, consider adding extra compost, vermiculite, or peat moss to help keep it moist.

The pH level for Persian shield should be between 5.5 and 7.5 for best growth.

These are extremely good as potted plants, and most people grow them that way to provide accents of purple foliage to their garden or home. However, they can work as bedding plants too, provided that you’ve developed a well-drained planting location for them.

Fertilizer

For most of the year, fertilizing should be done every two weeks with a half-diluted, low-NPK liquid plant food. Aim for one which is balanced NPK, as it requires the nitrogen to grow and the rest to develop healthy root structure and provide its brilliant color.

Slow down feeding your Persian shield as you move into the fall to once a month, and withhold fertilizer through the winter. Once the spring comes again, return to a regular 2-week pattern.

Propagation

It’s easy to propagate Persian shield plants from seeds or cuttings from the mother plant, but I find that cuttings work best.

Preparing your cutting is simplicity itself. Select woody stems that are 6″ long and remove all but the uppermost leaves. Place the cut end into either a glass of water or some moist rooting medium of your choice. If using water, change the water daily. In rooting medium, keep it evenly moist.

Place your Persian shield plants in a shaded location where they still get some indirect light, and ensure that the humidity is kept up around them (a plastic bag placed overtop can help with this). They will develop roots in 2-5 weeks, depending on their vigor and the season.

Repotting

Faded Persian shield
This plant may have had too much light, as its leaves are faded. Source: c_nilsen

Many people seldom repot these Persian purple plants if they’re thriving because they simply don’t need it. If your indoor plants look healthy and happy, then you’re doing just fine!

However, if you want to encourage your Persian shield plants to expand in size, they’ll need more root space. Also, if they seem to be going through water very quickly, switching to a pot that’s 1-2 inches larger will add more soil and help retain more moisture.

If you do opt to repot your Persian shield plants, prepare your soil in advance and have it ready. You may wish to gently open up the roots of each plant if they seem to be a bit pot-bound, then replant them at the same depth they were previously planted.

Try to avoid jumping drastically in pot size. A plant that was previously planted in a 4″ pot shouldn’t go up to a 12″ pot, as it’ll take forever for it to fill that much space.

Pruning

Other than removing leaves that have died back, there’s little pruning that needs to be done.

Pinch back stems to encourage your plant to become bushier. This can be done at any time that it’s required.

Your plant can get leggy as it gets older, during the winter, or if it needs to be repotted. If pinching back does not discourage the leggy habit, consider repotting. For the winter months, pinch off flower stalks and occasionally pinch back excess stem growth. You can even get a few cuttings to propagate while you prune.

While optional, some report that trimming the plant back to a foot tall (leaving enough leaves for photosynthesis) at the end of winter encourages their plants to burst forth with new vigorous growth in the spring.

Troubleshooting

Noctuid moth on S. dyerianus
A Noctuid moth resting on a Strobilanthes leaf. Source: dreed41

Diseases don’t seem to impact Strobilanthes dyerianus, and honestly, most pests won’t bother it much either. It’s extremely easy to care for provided that it’s got the right growing conditions. Still, a few things may come to call; here’s how you handle them.

Growing Problems

Your plant will wilt quickly if it has too little water, and it’s immediately obvious. If this happens, increase your frequency of watering to compensate, being sure to keep the soil moist and humidity up around the plant. It bounces back quickly even when in bad shape.

As mentioned earlier, too much light can cause the leaves of your Strobilanthes dyeriana to fade. Offering it some shielding from the direct sun can help to ease that problem. Older leaves will also fade in coloration prior to dropping off, which is not abnormal.

Pests

Very few pests can become an issue for your purple and green plants. However, there are still two that might appear, especially for those planted outdoors, and it’s best to clear them out before they can wreak havoc.

Spider mites, especially red spider mites, are the most common indoor pest you’ll deal with. These little mites will pierce the flesh of the iridescent purple leaves and suck moisture out of them, causing spotting and leaf yellowing.

Similarly, fungus gnats are a potential issue for Strobilanthes dyerianus. These gnats lay their eggs in moist soil, and the larvae will attack your plants if they have any signs of lowered resistance. The combination of mites and gnats together can be deadly!

Thankfully, both of these pests can be deterred by spraying neem oil on all plant surfaces and on the soil’s surface. While neem oil will not kill existing fungus gnat larvae in the soil, it can prevent the adults from laying their eggs there to begin with, and prevent mites as well.

An alternative that will penetrate the soil is a pyrethrin spray. This will kill fungus gnat larvae, as well as eliminate both adult gnats and spider mites.

Diseases

Almost no diseases whatsoever seem to have any effect on this plant! As plants that are accustomed to hot, humid conditions, they even appear to be immune to powdery mildew or other fungal leaf issues. Keep an eye out for damage caused by the pair of pests instead.

Frequently Asked Questions

Persian shield
Persian shield. Source: TexasEagle

Q: Does Persian shield like full sun?

A: To help the plant maintain its silvery foliage and bloom its purple flowers, opt for some shade. In full sun, you may see the leaves turn fully green.

Q: Is Persian shield an annual or perennial?

A: In most areas, it’s a tender perennial.

Q: Is Persian shield a good houseplant?

A: Because it has such a small hardiness range, most people choose growing persian shield indoors. Persian shield makes a great houseplant for those in cooler climates, much like many of the plants that grow in the subtropics.

Q: How do you care for a Persian shield?

A: This piece covers Persian shield care. However, give it bright light and good soil that drains well. You may prefer growing persian shield indoors in cooler climates or outdoors if you live in zone 10. Full sun works too but may reduce the brilliance of its colorful foliage.

Q: Should I mist my Persian shield?

A: If you’re growing in a dry area or indoors, you can mist entire plants daily with distilled water.

Q: What plants go well with Persian shield?

A: So many! Pick plants that enjoy partial shade and moist soil. Try combinations of purple and yellow flowers to offset the leaves of this plant.

Q: Can I cut back Persian shield?

A: Yes! Cut it back to keep it smaller or help the plant develop a bushier growth pattern.

Q: How do I overwinter my Persian shield?

A: Keep it in a sunny area, either indoors for potted plants or outdoors in zones with cooler climates. It can be a root hardy perennial in zones 8 and 9.

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