Jooni

An exemplary photo of a Nandina bonsai

Nandina

1 Species

Species

Nandina domestica

Nandina, also called heavenly or sacred bamboo (Nandina domestica), is an evergreen shrub from China and Japan that, despite its name, is not a bamboo at all but a member of the barberry family. A Nandina bonsai is prized for its year-round colour: pinkish-red new growth, delicate compound leaves that turn red to purple in autumn and winter, white early-summer flowers and clusters of glossy red berries.

It is one of the easier flowering shrubs for beginners. It is an outdoor plant that needs cool winters to colour well and does poorly kept indoors. It grows as a clump of mostly unbranched canes rather than as a classic tree, so it is usually styled as a multi-trunk or clump. All parts, especially the berries, are toxic to pets and birds.

At a glance Nandina domestica

Difficulty
Beginner
Placement
Outdoors
Light
Sun to partial shade
Watering
Moderate
Min. temperature
-5°C (23°F)
Foliage
Evergreen

Fertilizing

Feed every two weeks from spring to early autumn with a balanced bonsai fertilizer, or monthly with slow-release organic pellets. Stop feeding in late autumn and winter, when growth comes to a halt.

A slightly acidic fertilizer helps if your water is hard, because nandina develops yellow leaves in alkaline soil. Avoid heavy nitrogen feeding in late summer, which keeps the leaves green instead of colouring.

Placement

Keep your Nandina bonsai outdoors all year in full sun or partial shade; full sun gives the strongest red colour. In very hot climates, give it some shade in the afternoon.

The shrub is frost-hardy, but protect the roots of the potted plant once temperatures fall below about -5°C (23°F), for example in an unheated greenhouse, shed or cold frame. Cool winters are what turn the foliage red, so do not bring it into a warm room. In mild climates it can stay outside without protection.

Pruning

Nandina canes branch very little, so pruning is mainly about cutting tall canes back to encourage new shoots lower down and from the base.

  • Cut back overly tall canes in late winter or early spring, before new growth starts; new shoots usually appear within about six weeks.
  • Remove old, weak or dead canes at the base to keep the clump balanced.
  • Remove spent flower stalks if you don't want berries, or leave them if you do.

Young canes can be wired, but they are stiff, so bend them gently. Clump and twin-trunk styles suit its natural growth best.

Repotting

Repot every 2 years in early spring, just before new growth starts. Use a well-draining, slightly acidic bonsai mix, such as akadama with pumice and a little organic matter.

Prune the roots moderately and remove very old, woody roots. After repotting, keep the plant in a sheltered, semi-shaded spot for a few weeks while new roots grow.

Watering

Keep the soil evenly moist but never waterlogged. Check daily and water thoroughly when the top layer feels dry, until water drains from the bottom of the pot.

In summer it may need water every day; in winter, water less as growth slows, but never let the root ball dry out. Use rainwater if your tap water is very hard.

Seasonal care

  • Spring: Cut back tall canes and, every second year, repot in early spring before the pinkish new leaves emerge. Resume feeding every two weeks once new shoots appear.
  • Summer: Upright clusters of small white flowers open in early summer and, if left in place, develop into berries. Give full sun, with some afternoon shade in very hot climates, and check the soil daily.
  • Autumn: Cool nights and full sun turn the foliage red while the berries colour up. Stop feeding in late autumn and reduce watering as temperatures drop.
  • Winter: The foliage stays red to purple and the berries often last all winter, but they are toxic to pets and birds, so keep them out of reach. Do not feed, water less and protect the roots below about -5°C (23°F).

Common problems

Nandina is a tough shrub, and most problems come down to soil, water or a few common pests:

  • Yellow leaves with green veins (chlorosis): Usually caused by alkaline soil or hard water limiting iron uptake. Repot into a slightly acidic, well-draining mix, water with rainwater and give an iron supplement if needed.
  • Root rot: Drooping, yellowing foliage and a soggy root ball result from waterlogging. Let the surface dry between waterings and make sure the pot drains freely.
  • Scale insects, aphids and mealybugs: Sticky leaves, small bumps on the canes or white cottony clusters point to sap-sucking pests. Wipe them off, rinse the foliage and treat with insecticidal soap or horticultural oil.
  • Poor red colour: Too much shade, a winter spot that is too warm or late nitrogen feeding keeps the leaves green. Move the plant into full sun, let it experience cool nights and stop nitrogen-rich feeding by late summer.
  • Mottled or distorted leaves: Mosaic patterns, curling or stunted growth can signal a viral infection such as cucumber mosaic virus. There is no cure, so remove badly affected canes, control the aphids that spread it and keep your tools clean.