Persian Shield (Strobilanthes, pronounced stroe-buh-LAN-theez) is a heat-tolerant, tender perennial treated as an annual in zones 8b and colder. It has lavender flowers, but is grown for its foliage: deep green overlaid with bright purple and a metallic sheen. The foliage is beautiful in its own right, but when combined with other plants, especially pink or purple flowers, it makes them sing. It is ideal in a larger container. Provide rich, well-drained soil with plentiful moisture. When too dry, the leaves will droop. If a wilted plant is watered immediately, it will perk back up but too many repeats will result in leaf drop. Constantly wet soil will cause root rot.
Persian Shield will grow into a loose shrub up to 36 inches tall and 24 inches wide. It is much more attractive when the stem ends are pinched regularly to make a shorter, bushier plant. New growth is more colorful than older leaves. The plant looks best in partial shade. Too much sun will make leaves crisp around the edges; too little light makes them look faded.
Persian Shield is easy to propagate from stem cuttings or layering. It will survive in my home as a houseplant or in my greenhouse through the winter, but reduced light results in a spindly plant. I overwinter one specimen, then use it as a mother plant for several cuttings in spring. Rooted cuttings grow rapidly. Plants are occasionally attacked by spider mites.
A 14-inch container planted with a single Strobilanthes plant. The newest growth is distinctly more colorful than the older leaves.
A favorite combination: Persian Shield paired with purple Angelonia and red/purple bat-faced Cuphea. Next year I will select a glazed container rather than this terra cotta, to reduce evaporation and the need for daily watering. This photo shows the solid purple reverse side of the Persian Shield leaves.