The Persian shield makes a dramatic addition to the garden

Strobilanthes dyerianus. Picture courtesy Ali Eminov See their flickr pageStrobilanthes dyerianus. Picture courtesy Ali Eminov See their flickr pageThe colourful leaves of the perennial Persian shield provide vibrant contrast for shady gardens in subtropical regions, and in frosty regions they are planted as summer annuals or grown as indoor pot plants. Read more below on how to care for them.

Persian Shield has been grown both indoors and outdoors since Victorian times for its ornamental foliage, and it is easy to see how it was given the common name “Persian shield”, as it is flashy, with a purplish iridescence and silvery metallic sheen, and the bold green stripes along the veins of the leaves gives them the appearance of little battle shields. Each leaf can reach 10 to 18cm long and 7.5cm wide. Its common name is misleading, as it is not native to Persia, a historic region of southwestern Asia, which is now modern Iran, but rather to Myanmar (formerly called Burma).

This soft stemmed exotic shrub is primarily grown for its uniquely coloured leaves, but in warm climates it will produce pale blue flower spikes anytime from December to May.  However, budding is erratic and the factors that trigger reproduction are not understood. If grown in subtropical regions it can reach 1.5m tall with a spread of 2.5m, but in colder regions it will develop into a small shrub a little over 1m in height, with a spread of 80cm. 

In the Garden & Home:

Coleus may be the go-to foliage plant for some gardeners, but the stunning, quilted leaves of the Persian shield work equally well, making it a ‘go-to’ plant for shady spots in subtropical and tropical gardens worldwide. In frost free regions the Persian shield is treated as a short-lived evergreen perennial and it will develop into a lovely small shrub. In cold winter regions it is often planted out as a summer annual and used to add tropical flair to garden beds and pots.   

The Persian shield makes a stunning focal point as it stands out in any planting, and is particularly striking when paired with soft grey-greens, or yellow-greens ‘chartreuse’. Try planting it with coleus like the one with lime green leaves, and purple veins and margins.

For for a dramatic tropical effect, mix Persian shield with caladiums, elephant ears, or cannas. It also pairs nicely with silver shade-loving plants like dead nettle (Lamium).

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In cold winter climates potted plants can be brought indoors and grow as houseplants through the winter, and moved back outdoors in the spring. In fact, the Persian shield is a very popular houseplant in colder regions of the world.

Strobilanthes dyerianus. Picture courtesy SCFiasco See their flickr pageStrobilanthes dyerianus. Picture courtesy SCFiasco See their flickr pageCultivation:

Persian shield loves humid climates and does well in coastal gardens if it is sheltered from strong winds. In these warm, frost free regions it is grown as a short lived evergreen perennial. It is not very frost hardy, but in climates that are not too cold, it can be grown in protected spots away from cold winds, and where there is a tree canopy overhead. In areas with mild frost the plant may die back to the ground, but will often regrow the following season. In very cold and frosty regions this plant is grown as a summer annual, or as a potted patio plant which is brought indoors to overwinter.

In the cooler mist belt regions of South Africa the Persian shield can be grown in lots of sunshine, but in hotter summer regions it thrives in semi-shade to shade, and needs protection from the hot midday sun. It is a thirsty plant, and will quickly droop if it doesn't receive adequate water, but it typically bounces back quickly after a drink. The less water the Persian shield plant gets the more shade it will need. Mulching the roots will help to conserve moisture.

It adapts to most fertile and well drained garden soils, but thrives in the neutral range of soil pH, to slightly acidic soil. Try to keep the pH between 5.5 and 7.5. If grown in rich soil with plenty of moisture the Persian shield should only need light feeding at the start of the season and again about midway through the summer.

Pruning:

Since Persian shield is grown for its foliage and the flowers are not particularly showy, many gardeners like to pinch them off to encourage more leaf growth.  If left to grow on its own the plant can get tall, leggy, and floppy, so gardeners lightly pinch out some of the growing tips in spring  to create a fuller plant. Pruning is not required if you are growing it as a summer annual.

Propagation:

Taking cuttings is the best way to keep these lovely plants in your garden for long periods, by replacing them every few years with newly struck plants. Being soft stemmed, the Persian shield will propagate fairly easily from softwood cuttings taken in spring and early summer.

You can also start Persian shield from seed, but they require somewhat warm conditions between 13 and 18°C to germinate.

Indoors:

If kept indoors the Persian shield requires bright, indirect light to keep its colour. Make sure it has humid conditions, as dry air will cause the leaves to dry and drop. Placing a humidifier nearby, or placing the pot on top of moist pebbles in a drip tray, as well as misting the plant down daily is recommended, but be sure to use soft water, as chlorine will damage the leaves. Grouping it together with other tropical plants with the same growing requirements will create a tiny microclimate and benefit all the plants.

A good potting soil should suffice for potted plants, and they can be fed occasionally with a liquid fertiliser during summer. Pinch back the growing tips if the plant is becoming a bit big and leggy, and re-pot young plants annually until they reach their maximum size, then repot every other year. Root-prune older plants when re-potting, to control their size, and take cuttings every couple of years, as the mother plant can become very leggy and unattractive and should be discarded at this stage and replaced with the new cuttings.

Problems, Pests & Diseases:

Persian shield is generally pest and disease free, and is not usually susceptible to fungal disease or other problems with the foliage, except for water stress and spotting.

Red spider mites, aphids and whiteflies can become pests, especially when the plants are drought-stressed, or are grown in enclosed glasshouses or under roofs outdoors.

Indoors plants may become infested with spider mites, aphids or mealybugs.

Warning:

Generally speaking, members of the Acanthaceae family are non-toxic. Anecdotal evidence suggests that the sap of Persian Shield may be irritating to the skin.