Golden shrimp plant

Identification and origin

Pachystachys lutea belongs to the acanthus family, Acanthaceae, along with nerve plant (Fittonia) and polka dot plant (Hypoestes). It is native to lowland areas of Peru and northern Brazil, and it has naturalized elsewhere in Central America and the Caribbean.

It is an evergreen tropical shrub with soft stems that can reach 2–6 ft in its native habitat. In containers it stays much smaller, usually 12–18 in, and rarely exceeds 3 ft. The opposite, lance-shaped to elliptic, dark green leaves grow up to 6 in long; their deeply set veins give them a corrugated look.

The real eye-catchers are the flower spikes: upright, four-sided cones 3–5 in long, made of overlapping golden-yellow bracts that resemble the scales of a shrimp. The true flowers are white, two-lipped tubes that poke out from the bracts and open one after another from the bottom of the spike to the top. On each spike, the white flowers keep coming for several weeks. In the tropics the plant blooms all year; in temperate climates it blooms mainly in summer unless it gets very bright light. A plant less than 12 in tall can already flower.

Don’t confuse it with shrimp plant (Justicia brandegeeana), a related species with drooping bracts.

Light

To bloom well, golden shrimp plant needs plenty of light. Indoors, set it in front of a very bright or even sunny window in a warm room. Medium light keeps the foliage going, but flowering becomes scarce. Outdoors in summer, it grows in sun or partial shade; in very hot climates, light shade during the hottest hours suits it better.

Few flower spikes and stems that stretch and lose their lower leaves almost always point to a lack of light.

Watering

During growth and bloom, keep the mix evenly moist without overdoing it: water when the surface starts to dry, moistening the whole root ball, then empty the saucer so the pot does not sit in water. In winter, when growth slows, water sparingly and let the mix dry a little more; gradually return to more generous watering in spring as new shoots appear.

Before each watering, feel the mix: the state of the root ball, not the calendar, should guide you. A clay pot dries out faster than a plastic one.

The plant appreciates fairly high humidity. During the heating season, group plants together or set the pot on a tray of moist gravel without letting the bottom touch the water; a humidifier is even more effective. Misting raises humidity for only a few minutes.

Potting mix

Use a fertile, well-drained mix rich in organic matter and on the acidic side. A homemade blend works very well: one part garden loam or potting soil, one part sand, perlite, or vermiculite, and one part peat moss or a peat-free substitute. The pot must have drainage holes.

Golden shrimp plant is a heavy feeder: fertilize regularly during the growing season to keep the foliage deep green and support flowering. It does not tolerate salt well, so avoid overfeeding and flush the mix with plenty of plain water from time to time to wash out accumulated salts.

Temperature

It likes comfortable indoor conditions, ideally around 75 °F during the day and 64 °F at night. Below 61 °F, it starts dropping leaves. Keep it away from cold air currents, especially at night when the heat is turned down.

It can spend summer outdoors in a pot on a patio or balcony. Bring it back inside in late summer or early fall, before nights drop toward 41 °F. In the ground, it is grown year-round only in USDA zones 10 and 11; in zone 9b, a hard freeze kills the top growth, but the plant can regrow from the roots. A plant that survives a light frost is left bare and takes a long time to recover.

Repotting

Repot when the plant becomes top-heavy for its pot, fills it with new shoots, or sends roots out of the drainage holes. Choose a pot only slightly larger, 1–1 in wider: an oversized pot holds too much mix, which stays wet and encourages root rot.

To keep the plant in the same pot, root-prune it instead: tease the roots away from the root ball, trim them back to within 1–1 in of it, and replant with fresh mix.

Pruning

Pruning is the key to a good-looking plant. Left alone, golden shrimp plant gets leggy, bare at the base, and top-heavy. Cut it back hard once a year to keep it a reasonable size and a pleasing shape. During the growing season, pinch out the tips of young stems to make them branch: you will get a bushier plant and more flower spikes. Also cut off faded spikes, which encourages new blooms. Outdoors, low-growing plants at its feet hide the bare lower stems.

Propagation

Cuttings root very easily. In early summer, take 4 in tip cuttings from softwood or semi-hardwood stems. Dip the base in rooting hormone to improve rooting, then insert them in a rooting mix kept lightly moist. Once rooted, pot them up individually: they bloom young, even before reaching 12 in. Stems removed during pruning also make good cuttings.

Common problems

• Leaf drop: temperature below 61 °F, a cold air current, or a root ball left too dry.
• Few or no flower spikes: too little light, too little fertilizer, or stems never pruned or pinched.
• Tall plant, bare at the base: no pruning, or light that is too low.
• Root rot: overwatering, an oversized pot, or a saucer full of water.
• Browning leaf edges: too much fertilizer or salt buildup in the mix.
• Pests: the plant is susceptible to them, especially indoors. Watch for spider mites, mealybugs, scale insects, whiteflies, and aphids. Check the undersides of leaves and the stems regularly.

The same symptom can have several causes, so always compare light, watering, temperature, and root health.

Toxicity

No toxicity has been reported for dogs, cats, or people. As with any plant, an animal that chews the leaves can still have a mild, short-lived upset stomach, with no serious effects expected.