Bamboos thrive in moist, but well-drained soil in a sheltered spot. They tolerate most soil types, but some, such as Shibatea, require acid soil or ericaceous potting compost. Bamboo will grow in poor soils, but not in constant wet, boggy or extremely dry conditions.
Plant in spring so that energy stored in the bamboo's rhizomes is used to produce strong, new canes in summer. These rhizomes then produce roots before the plant becomes dormant from autumn to spring.
Before planting, dig in well-rotted garden compost or manure to raise the organic content of the soil. This will also improve its ability to hold moisture.
There are bamboos for nearly every garden and here are some popular choices:
- For a shady spot: Chimonobambusa
- For direct sun: Phyllostachys
- For an exposed site: Bashania, Pseudosasa, or Sasaella (and consider erecting a temporary netting windbreak during plant establishment)
- For any garden: Pseudosasa and Indocalamus are completely unfussy
Types of bamboo
Bamboos are either classed as running or clump-forming bamboos.
Running bamboos, also known as invasive bamboos, produce long rhizomes (underground stems), which grow away from the main plant and will spread rampantly if not contained.
The following are running bamboos: Arundinaria, Bashania, Chimonobambusa, Clavinodum, Hibanobambusa, Indocalamus, Phyllostachys, Pleioblastus, Pseudosasa, Sasa, Sasaella, Sasamorpha, Semiarundinaria, Sinobambusa and Yushania.
Clump-forming bamboos grow in tight clumps and are less invasive and include: Bambusa, Chusquea, Dendrocalamus, Drepanostachyum, Fargesia, Himalayacalamus, Schizostachyum, Shibataea and Thamnocalamus.
Plant in spring so that the food reserves in the rhizome are used to produce a good flush of fresh canes in summer.
- Dig the soil over and add organic such as well-rotted manure or garden compost to condition the soil and improve its water-holding capacity
- The planting hole should be dug so that the rootball sits slightly low, with 2-3cm (1in) of soil covering the original surface
- When filling in around the rootball and firming with the soil and compost mix, take care not to damage the young rhizomes
- Water and mulch after planting
Watering and Feeding
- Water regularly during dry periods
- Bamboos require a high level of nitrogen in spring and a balanced fertiliser through the rest of the growing season until late August
- Allow bamboo leaves around the plants. This foliage contains silica which helps provide strength and stability
Planting inside a physical barrier
New bamboo plants or divisions can be contained within a physical barrier to prevent them spreading through beds and borders.
- Dig a trench at least 60cm (2ft) deep, but ideally 120cm (4ft) deep
- Line the sides of the trench with either solid materials (such as paving slabs, corrugated iron sheets or pre-cast concrete drain sections) or with fabric (such as root barrier fabric obtainable from Green Tech Ltd or industrial linoleum (2mm (1/8in) thick), available from builders merchants). Butyl pond liner is not suitable, as the bamboos’ underground stems can penetrate this
- Fabric ends should be overlapped by at least 30cm (1ft) and bonded with appropriate mastic
- The barrier should protrude at least 7.5cm (3in) above soil level, to prevent the bamboo stems arching over the top. The protruding edge can be disguised with decorative mulch or stones
- The planting hole should be dug so that the rootball sits slightly lower than the original depth, with 2-3cm (1in) of soil covering the original surface
- Firm well when backfilling, taking care not to damage the young rhizomes
- Water well and mulch after planting
Smaller bamboos make ideal container plants grown in a large pot (at least 45cm (18in) across and deep) in loam based potting compost such as John Innes No 3.
When planting, incorporate controlled release fertiliser pellets and water retaining gel in the compost. During summer, water frequently and feed with a liquid feed regularly. Reduce watering and stop feeding in winter. Ensure that bamboo plants in containers do not try out in winter, however, since the foliage is prone to wind scorch.
In very cold weather, insulate containers with bubble wrap or move them to frost-free conditions.
Routine bamboo maintenance
With a little effort it is easy to keep bamboos looking good and prevent them from becoming a nuisance in the garden.
- In spring, remove any weak, dead, damaged or spindly canes, cutting them to ground level with secateurs or loppers
- At the same time remove any debris at the base of clumps
- To show off plants to their best, remove some of the foliage from the bottom of the canes. Either snap the side branches off with a swift downward motion (wearing gloves) or cut them back with secateurs, pruning as close to the main cane as possible to leave a smooth finish
- Irrigate in dry spells, as bamboo prefers moist but well drained conditions
Contrary to popular myth, bamboos do not always die after flowering, although the chances of full recovery are not good. They flower infrequently and it can be dramatic, with browning of the foliage and development of tall, feathery, grass-like flowers. Flowering can weaken a clump, but the following steps may result in recovery:
- If you see the odd flowering shoot, cut it out promptly to discourage more from forming
- If the whole clump starts flowering, allow it to do so undeterred, even if the clump looks terrible. Continue to feed and water. The following spring, cut back the clump to ground level and feed with a high nitrogen fertiliser such as a spring lawn feed to encourage new green growth from the base
Divide in mid-spring, splitting clumps apart with a mattock or axe, or lifting smaller clumps and cutting them in half with a saw.
Rhizome cuttings can be taken in early spring;
- Choose one, at most two year old canes and cut the soil away from around the plant
- Cut the rhizomes from the main plant
- Reduce the canes to at least 30cm (12in)in length
- Place the cutting horizontally in a deep tray of gritty compost and cover lightly
- Water the cuttings and place the tray in a plastic bag in a warm position such as a warm shed or house
- Plant out in the following spring when the risk of frost is passed
Bamboos can be propagated from seed, although, because supply is irregular, it is a less common method of propagation. Sow seed fresh as soon as it is ripe. Viable seeds feel solid like grain - papery ones are not viable.
- Use a multi-purpose compost with 50 per cent vermiculite added to provide good drainage
- Many species germinate within a week or two in a minimum temperature of 10°C (50°F)
- To reduce the risk of damping off, keep seedlings growing through winter in the house, or alternatively in cooler, but dryer conditions