China doll

Identification and origin

Radermachera sinica belongs to the family Bignoniaceae. It is native to southern and eastern Asia: southern China, Taiwan, Assam and the eastern Himalaya, Myanmar, and Vietnam, where it grows in subtropical mountain areas. It was long known as Stereospermum sinicum. The genus name honors J. C. M. Radermacher, a Dutch naturalist who lived on Java, and the epithet sinica means “Chinese.”

In the wild it is an evergreen tree that can reach 98.5 ft; grown outdoors in frost-free climates it usually stays around 24.5–29.5 ft. In a container it forms a bushy shrub that rarely exceeds 4–6 ft tall and 3.5–5 ft wide, and it takes five to ten years to reach its mature size.

What makes it recognizable is its twice-compound (bipinnate) leaves, up to 2.5 ft long, divided into many very glossy leaflets, dark green to mid-green and about 2 in long. The overall effect is bushy and airy. In its native habitat it blooms in spring and summer, with panicles of fragrant, trumpet-shaped white or yellow flowers with crinkled petals, about 3 in long, followed by slender, inconspicuous capsules. Indoors it very rarely flowers: it is grown for its foliage. Dwarf varieties exist, suited to indoor or patio use.

Light

Give it plenty of light, but filtered. The ideal spot is near an east-, west-, or south-facing window, behind a sheer curtain that softens the sun for several hours a day. Avoid full direct sun through the glass, which overheats the foliage.

Too little light produces long, weak stems and paler leaves. If new shoots stretch out, move the plant closer to the window, once and for all, because it reacts badly to repeated moves.

Watering

This is the trickiest part. The plant is very sensitive to both underwatering and overwatering, and in either case it responds by dropping leaves. The goal is a potting mix that stays lightly and evenly moist, never soggy, and is not allowed to dry out completely.

Before watering, push a finger into the mix: when the top 1–1 in feels dry, water thoroughly until water runs out of the drainage holes, then empty the saucer. Never leave the pot standing in water: suffocated roots rot. A clay pot or a small pot dries out faster, so check those more often.

The leaves tell you what is going on. Leaves that turn black point toward too much water, while dry, crispy leaves point toward too little. After overwatering, wait until the surface of the mix is thoroughly dry before watering again.

The plant tolerates the dry air of heated homes, but it appreciates regular misting of the foliage.

Potting mix

Use a soil-based potting mix, or a peat-free multipurpose mix with added sand or horticultural grit for drainage. In the ground it likes rich, loamy, evenly moist, well-drained soil with a neutral pH. The pot must have drainage holes.

Fertilize only during active growth, in spring and summer, with a houseplant fertilizer. Stop in fall and winter, and wait for new growth to appear before feeding a plant that has just been bought, moved, or repotted. Nitrogen deficiency shows as a uniform pale green to yellow color that appears first on the oldest leaves.

Temperature

It is comfortable at about 70–75 °F during the day and 61–64 °F at night. In winter it should not drop below 50–59 °F; it is best to stay toward the top of that range, because it likes a warm environment. It cannot tolerate frost.

In summer you can move it to a sheltered patio or porch, in partial shade and out of the wind, as long as you bring it back indoors before the first fall frost. That change of surroundings alone can cause leaf drop. In the ground it is grown in USDA zones 10 to 12, in full sun to partial shade, in a spot protected from strong winds.

Repotting

Repot during the active growing period, in spring or summer, rather than in fall or winter when the plant is resting. Choose a pot in proportion to the size of the plant, with drainage holes. Repotting is stressful: combined with a move or overwatering, it can send the plant into real shock and heavy leaf loss. So avoid repotting a plant that has just arrived in your home: let it settle into its new spot for at least a month first. Afterward, water moderately and do not fertilize until growth resumes.

Pruning

Pruning keeps the plant compact and stops it from becoming bare at the base. On a young plant, pinch out the shoot tips to encourage branching. On an older plant, shorten stems that have grown too long to keep it within the space available.

Propagation

Propagate it from stem cuttings in summer, using semi-ripe material. Take a shoot tip 3–6 in long with at least two nodes, remove the leaves from the lower half, and dip the base in a little rooting hormone, without overdoing it, because too much slows root development. Insert it in a light mix of vermiculite, perlite, or peat, never in garden soil or compost. Keep it in bright, indirect light; a rooting mix held at about 75–81 °F gives the best results.

Air layering suits thicker stems: wound the stem, wrap the cut in moist moss, cover it with plastic wrap, and once roots have formed, cut below the new root ball and pot it up right away.

Seeds are sown in a loose potting mix, barely covered, and kept moist.

Common problems

• Leaf drop: a move, repotting, a change in light or temperature, but also overwatering or underwatering.
• Blackened leaves: too much water, or a pot without drainage holes.
• Dry, crispy leaves: not enough water.
• Sparse plant, stretched stems: insufficient light or no pinching.
• Old leaves uniformly pale or yellow: nitrogen deficiency.
• Root rot: a mix that is constantly too wet.
• Pests: aphids, mealybugs, scale insects, and spider mites. Check the foliage and young shoots regularly.

A single symptom can have several causes: always check how moist the root ball is, the light, and any recent changes before acting. A plant that has lost many leaves can take a long time to fill out again, and sometimes never fully regains its former density.

Toxicity

No toxicity reported. The plant does not appear among the plants listed as toxic to dogs and cats, and it is not known to be poisonous to people. If someone feels unwell after swallowing part of it, contact a veterinarian or a poison control center.