- Jardin botanique
Bamboo belongs to the grass family (Poaceae) as do corn, wheat and lawn grass. There are over 1,200 species of bamboo, mainly in Asia. The largest bamboo grow in tropical regions, but several dwarf or medium-sized species grow in temperate regions.
In tropical regions, under optimal conditions, bamboo species grow rapidly and reach an enormous size. For example, the stems (culms) of Dendrocalamus sinicus, a Chinese species, measure 30 cm in diameter and 30 metres in height.
Bamboo can be used for almost anything: scaffolding, furniture, floors, bed linens, clothing, baskets, etc. The young shoots are even edible!
Hardiness: Most bamboo species thrive in a hot humid climate and are unable to withstand temperatures below -10ºC. At our latitude, it is best to overwinter bamboo indoors.
In Québec, few species are truly hardy except for a few dwarf bamboo that shelter under a blanket of snow, the best winter protection. However, since winter conditions are highly variable (rain, intense cold, loss of snow cover), their survival is never assured.
Bamboo cultivation is so recent in our climate that there is little reliable data on their hardiness. Although the underground plant parts are resistant to the cold, being protected, the persistent foliage and stems are likely to freeze. It all depends on the severity of the winter. Generally, stalks must be cut down to the ground every spring.
Cultivation: In the house, adequate light and a high humidity level are required. Put your plant in front of a south- or west-facing window and spritz the foliage regularly.
The ideal planting medium is a mixture of potting soil for indoor plants (50%) amended with coarse sand (25%) and compost (25%). Watering should be well managed because bamboo cannot tolerate waterlogged soils (the pot must have drainage holes) and drought will cause the leaves to curl.
In the active growth period (March to September), fertilize with a balanced fertilizer (20-20-20) or a natural seaweed or fish-emulsion fertilizer. Water thoroughly, making sure to empty the saucer after half an hour. During the summer, place the pots on the deck or bury them in the flowerbed and water the bamboo regularly. You can also remove the bamboo from its pot and plant it right in the garden in rich, well-drained soil.
In the fall, bring your pots indoors before the frost and overwinter the bamboo in a bright but cool room (10-15°C). During the winter, water only often enough to prevent the soil from completely drying out, but spritz the foliage regularly. Stop fertilizing. It is normal for foliage to drop off heavily during the winter, but it will grow back in the spring.
Soil: Bamboo is suited to all soil types, provided they are well drained. When planting, some added compost will be enough to meet their needs. Avoid nitrogen fertilizers, which will make stems weak and brittle.
Types of rhizomes: Some bamboo have creeping rhizomes (narrow, long and deep) that can become invasive. They make excellent ground cover, but it is best to delimit the bed with buried landscape edging. Other species have clumping rhizomes (fleshy and squat). Not invasive, they are well suited for growing in pots, in clumps or as hedging.
Exposure: Full sun or semi-shade.
Watering: Water thoroughly when planting to encourage root establishment. During the summer, keep the soil moist by watering regularly.
Pruning: In the spring, cut away any sections of stems blackened by frost and cut off dead stems at ground level. The rhizomes that have survived will issue new shoots.
Dividing: Like perennials, bamboo clumps can be divided, but you will need a saw because the rhizomes are very woody.
Winter protection: Dwarf bamboo do not generally need any protection other than a good layer of snow. It is wise to apply a layer of mulch if snow is scarce. Tall species must be overwintered indoors. Overwintering outdoors can be attempted by covering them with geotextile fabric, but there is a risk of freezing.
At the Montréal Botanical Garden: Most of the bamboo plants in the Chinese Garden are dug up in the fall, put into large plastic pots and kept in a cold greenhouse (5-7°C) through the winter. Each spring they are replanted outside.
In recent years, we have been testing the hardiness of some species of Phyllostachys and Arundinaria by covering them with a protective tunnel around the end of November. First, some canes are arched and a protective dome is shaped with flexible material (fibreglass lath), then it is all covered with a laminated geotextile fabric, in the hope that snow will be abundant. Despite this, the state of the plants varies depending on the severity of winters and the amount of snow.
Some relatively hardy dwarf bamboo varieties
- Pygmy bamboo (Arundinaria pygmaea). Height: 20-60 cm; Zone 4 with protection; creeping rhizomes.
- Dwarf bamboo (Arundinaria pumila). Height: 20-60 cm; Zone 4; creeping rhizomes.
- ‘Yakuzara’ dwarf bamboo (Sasa ‘Yakuzara’). Height: 1 m; Zone 5 with protection; creeping rhizomes.
Some medium-sized bamboo varieties, semi-hardy with protection (test in your region)
- Black bamboo (Phyllostachys nigra). Height: 1.2 m; Zone 5 with protection; clumping rhizomes.
- Yellow groove bamboo (Phyllostachys aureosulcata). Height: 1.8 m; Zone 5 with protection.
- Golden bamboo (Phyllostachys aurea). Height: 1.8 m; Zone 5 with protection; creeping rhizomes.
- Umbrella bamboo (Fargesia murielae). Height: 1.5 m; Zone 4 with protection; clumping rhizomes.
But be careful! Don’t confuse bamboo with Japanese knotweed (Polygonum cuspidatum, syn. Fallopia japonica), also known as Japanese bamboo or Mexican bamboo. Equipped with powerful roots, this hardy perennial with hollow gnarled stems reaching 2 to 3 m in height bears an uncanny resemblance to bamboo. Its roots produce copious runners and every year the species invades thousands of square metres of Québec land, eliminating everything in its path except fully grown trees. Don’t plant it in your garden and don’t throw the roots and stems in ditches!
To learn more about bamboo, visit our virtual exhibition Bamboo in Daily Life.