Semiarundinaria - Noble Bamboo: Planting and Growing

Botany and description

The genus Semiarundinaria (family Poaceae) comprises 7 species of bamboos, the most well-known and cultivated being Semiarundinaria fastuosa, Semiarundinaria yashadake and Semiarundinaria makinoi. These bamboos, called Medium Bamboos or Noble Bamboos, are native to China and Japan. According to botanists, the Semiarundinaria genus is believed to be a hybrid with one parent from the Phyllostachys genus, from which it inherited its upright, almost columnar habit.

Semiarundinarias are medium-sized bamboos (no more than 10 m tall) with moderate to slow growth. They are considered running bamboos, especially in warm climates. In cooler climates, noble bamboos tend to be far less invasive.

Noble bamboos have a distinctly vertical and compact columnar habit, forming narrow columns 2 m to 3 m wide. The culms are shiny, very straight and cylindrical canes, of a beautiful medium green, streaked with purplish-brown, 4 to 6 cm in diameter (2 cm diameter for Semiarundinaria yashadake and Semiarundinaria makinoi). These canes develop beautiful purple hues as they age, especially in sunlight, turning orange in autumn. The culms reach up to 10 m depending on the species and bear short shoots along their entire length.

Each shoot carries large, lanceolate green leaves, glossy, about ten centimetres long. The foliage is evergreen (down to -15°C), dense and flexible. The culm sheaths, pearly and shiny, are semi-evergreen, remaining attached to the canes for 3 months before falling. These sheaths also provide a beautiful colour contrast between themselves, the purple canes and the green leaves.

Semiarundinaria fastuosa, culm and silhouette on the right (© Leonora Enking)

As with all bamboos, the flowers, pseudo-spikelets, are insignificant and hidden by the foliage. They appear intermittently in fine, arching panicles. Generally, flowering is very rare. The development of an inflorescence leads to the death of the plant, with the culms withering and dying after flowering.

Semiarundinarias are typically used, due to their compact columnar habit and dense evergreen foliage, to create a magnificent green screen, conceal a view or form a windbreak. Allow a planting distance of 1 m to 1.50 m between each bamboo. Noble Bamboo can also be planted in the garden as a standalone clump, alongside other bamboos or large trees with Asian inspiration (Japanese Maple, Cornus kousa…).

Please note: Semiarundinaria fastuosa has been awarded the Award of Garden Merit by the Royal Horticultural Society (RHS) for its exceptional ornamental qualities.

The best varieties

Semiarundinaria fastuosa - Medium-sized Bamboo

Semiarundinaria fastuosa is a remarkable bamboo with exceptional qualities, ideal for tall hedges, privacy screens and windbreaks due to its dimensions. Slightly running and extremely hardy, it is beautifully decorative with its compact columnar habit, colourful culms and dense foliage.

• Height at maturity 7 m

See the product sheet

Semiarundinaria fastuosa var. viridis

The 'Viridis' variety differs from Semiarundinaria fastuosa (type species) by being slightly smaller in size with somewhat darker green foliage.

• Height at maturity 6 m

See the product sheet

Semiarundinaria yashadake f. kimmei

Semiarundinaria yashadake 'Kimmei', sometimes called red bamboo, is a cultivated variety prized for its graceful habit as well as the fantastic colouring of its culms which range from bright yellow to dark red through coppery tones, depending on season, exposure and age.

• Height at maturity 4,50 m

See the product sheet

Semiarundinaria makinoi

Semiarundinaria makinoi, dense, bushy, evergreen and tolerating pruning perfectly, is an ideal bamboo for creating medium hedges, mazes, windbreak or privacy screens that remain fully green throughout the year.

• Height at maturity 3,50 m

See the product sheet

How to plant Semiarundinaria?

Where to plant?

Semiarundinarias are quite hardy and can be grown throughout France and Belgium. However, avoid planting them in areas exposed to cold, dry winds.

Medium-sized bamboos thrive in partial shade, but tolerate full sun well.

Generally, bamboos—and Semiarundinarias are no exception—prefer neutral or acidic soil, not overly chalky, rather rich, moist, and well-drained. They appreciate slightly damp soil in summer but cannot tolerate waterlogged roots in winter: overly heavy, compacted soil that becomes waterlogged in winter would lead to fatal rotting.

Warning! Semiarundinarias are running bamboos, especially in mild climates (much less so in cooler climates). You can control the spread of their running rhizomes by installing a root barrier around the planting area from the outset, made of polypropylene and planted vertically in the ground around the young plant.

→ To learn more, read our guide: How to install a root barrier?

When to plant?

The ideal time to plant Semiarundinarias is late summer to autumn, from late August to October, after the peak heat. Planting can also be done between March and April (after the last frosts) in regions north of the Loire or between September and November in regions to the south.

How to plant?

Semiarundinarias can be grown either in the ground or in pots.

In the ground

• In a wide and deep hole, install the root barrier to control the spread of running varieties. This barrier should protrude 5 cm above the soil;
• Place the bamboo rootball in the centre of the hole;
• Backfill with the excavated garden soil, adding good planting compost and manure;
• Water thoroughly with 10 litres at planting time: this helps eliminate air pockets between the roots and soil while ensuring the roots are well hydrated. Bamboos need plenty of water to establish: water very regularly in the first year after planting, especially in summer when the soil is very dry;
• Apply a thick mulch (wood chips, pine bark, miscanthus…) around the base to retain moisture. Over time, fallen dry leaves will form a natural mulch at the base.

Please note: for a hedge or screen, space Semiarundinacea plants one metre apart.

In pots

Medium-sized bamboos adapt well to container growing, provided watering is not neglected.

• Choose a sufficiently large pot, at least 50 cm deep, with drainage holes;
• Add a drainage layer at the bottom: gravel or clay pebbles;
• The substrate should be a rich mix (half planting compost or rose compost and half garden soil) with good drainage;
• Place them in a spot with non-scorching sun or partial shade, sheltered from cold draughts;
• Potted bamboos must never dry out: monitor watering closely, ensuring it is very regular, especially during prolonged dry spells. You can spread mulch on the surface to keep the substrate cool.

Semiarundinaria ‘Yamadori’ (© Leonora Enking)

Pruning and maintenance

Watering

Bamboo requires plenty of water to establish and grow. Water generously when planting and then very regularly for the first two years of cultivation, especially in summer and when the soil is very dry. Don’t forget to apply mulch to keep the soil cool. Over time, bamboos “mulch themselves” thanks to their dry leaves, which decompose very slowly. After two years of cultivation, semiarundinarias tolerate drought well.

Potted specimens require even more careful monitoring of watering: do not let the soil dry out too much between waterings. Each semiarundinaria plant can drink up to 5 litres per day during hot weather.

Maintenance

Bamboos thrive in rich soil. Each spring, an application of compost at the base of the canes will be beneficial. For bamboos grown in pots or containers, a special bamboo fertiliser, rich in nitrogen, can be applied twice a year.

If the leaves of bambusas start to yellow, this may indicate excess lime in the soil. In this case, applying a little ericaceous compost on the surface or a pine needle mulch should solve the problem.

Pruning

Every year, cut back dry culms to the base (the dry canes can be used as stakes or for making decorative fencing), the least vigorous and most troublesome ones. All these pruned canes will not regrow, but this maintenance pruning will allow the plant to develop entirely new foliage that is denser. The appearance of the bamboo will be greatly improved.

Propagation of medium-sized bamboo

Medium-sized bamboos are best propagated in spring (March-April), by dividing clumps that are at least three years old. This operation should be carried out when the soil is sufficiently moist, which makes the process easier.

Dividing clumps:

• Using a sharp spade, remove a good-sized clump with at least 3 to 5 culms from the outer edge of the main clump;
• Shorten the culms by one-third of their length, always retaining some foliage, otherwise the clumps will not recover;
• Plant the clump in a prepared hole enriched with good compost;
• Backfill the hole with the excavated soil, firm down and mulch;
• Water thoroughly to eliminate any “air pockets” between the soil and the rootstocks, then keep the soil moist, but never waterlogged;
• Spray the foliage regularly with non-calcareous water in dry or windy weather, either in the evening or morning. This will prevent the leaves from drying out and ensure successful establishment.

Please note: once divided, larger bamboos revert to their juvenile stage. The new culms that emerge will then be smaller in size and girth. It may take several years before they regain the dimensions of the parent plant.

Semiarundinaria Yashadake ‘Kimmei’ (© Leonora Enking)

Pests and Diseases

Bamboos are resistant to most diseases and parasites. However, they can become vulnerable when weakened by excess water or a lack of nutrients.

When the weather is hot and humid, bamboos grown in pots are sometimes prone to attacks by mealybugs which feed on the sap and leave farinose or cottony white clusters on the plant. The leaves turn yellow and fall off, which can lead to the death of the plant in severe infestations. Spraying a mixture of vegetable oil (rapeseed or olive oil), 90° alcohol and black soap can suffocate them.

Red spider mites can also cause yellowing and drying of potted bamboo leaves, which eventually fall off. In this case, there are various eco-friendly solutions presented in the advice sheet Red Spider Mite: Identification and Treatment.

→ Want to learn more about bamboo diseases and parasites? Read our advice sheet Bamboo Diseases and Parasites

How to pair Noble Bamboo?

The Noble Bamboo, with its density, evergreen foliage and wind resistance, is ideal for creating compact hedges.

However, medium-sized Bamboo can also be planted in the garden as a standalone clump. To echo its Asian origins, you can pair it with plants from the same continent that thrive in similar growing conditions.

For trees, consider a beautiful Cornus kousa ‘Satomi’, a classic among flowering dogwoods, with its stunning pink bracts in spring. To contrast with the bamboo’s foliage in shape and colour, the Cercidiphyllum japonicum ‘Glowball’ or Katsura tree is a magnificent deciduous tree, prized for its heart-shaped leaves with changing hues and the caramel scent its leaves emit when they fall in autumn (or when hit by a late spring frost…).

More exotic but still from the same region, the Chinese Windmill Palm (Trachycarpus fortunei), a very hardy palm, will add striking architectural interest. Using Japanese Forest Grass (Hakonechloa macra ‘Aureola’) as ground cover will subtly echo the bamboo foliage.

Alternatively, don’t hesitate to play with graphic contrasts between the bamboo’s upright canes and lanceolate leaves by pairing it with plants that are wider than tall, with softer curves and broader leaves… Colour harmony is also key: subtle echoes of the Semiarundinaria’s purple canes through flowers or foliage in similar tones will remain pleasing to the eye. And finally, don’t feel constrained by a strictly “Japanese-style” garden. Let loose! No one’s forcing you to plant bamboo alongside other Asian plants. Be creative while respecting the basic needs of your chosen plants, bamboo or otherwise.

Semiarundinaria yashadake ‘Kimmei’, Cornus kousa ‘Satomi’, Hakonechloa macra ‘Aureola’ and Trachycarpus fortunei