Bamboos are valuable ornamental plants with attractive, lush evergreen foliage that can be used to add a tropical effect, style, movement and panache to any garden. Easy to grow and fully hardy, they come in almost 10,000 varieties ranging from huge tropicals to tiny dwarfs, and have become increasingly popular and fashionable over recent years for a variety of settings. With a few hundred varieties being suitable for the British climate, they are ideal for using as focal points, adding structure, height and movement to your borders or implementing as a windbreak, hedge or screen.
Bamboo as a centre-piece
Bamboo as a privacy screen
Bamboo used for ascent
As part of the grass family, bamboo plants are native to South East Asia, sub-Sahara Africa, the mid-Atlantic United States and parts of South America, where they are of notable economic and cultural significance acting as a food source, building material and versatile raw material for the indigenous populations. Bamboos have hollow stems which emerge from the ground at their full diameter and grow to their full height in a single growing season of three to four months. During this time, new canes grow vertically without branching; only when most of the mature height is reached do branches extend from the nodes and leaves start to appear. During the following year, the pulpy wall of each cane, or culm, slowly hardens and by the third year the culms are considered fully mature.
Choosing a Bamboo (Clump forming vs. Running Varieties)
It is important to choose a bamboo that is suitable for what you want it to do and appropriate for your situation and size of garden. Bamboos can be divided into clump-forming and running varieties, with both having specific uses and benefits. Running bamboos spread by rhzomes (horizontal underground stems) which help the plant to colonise new areas and may spread aggressively if not contained. Planting instructions and recommended garden care must be followed to ensure running bamboos do not pop up in parts of your garden where they are unwelcome. They are probably not the right choice for small gardens, unless you are reasonably experienced at the necessary containment techniques!
Running bamboos spread via underground rhizomes
Clump forming bamboo spreads much more slowly
Clump-forming bamboos spread slowly because, like ornamental grasses, the growth pattern of the rhizomes is to simply expand the root mass gradually. They work well as big specimen plants in lawns or as mixed border plantings, as well as being easier to keep in containers than running bamboo.
Bamboo Varieties in Focus
Fargesia Bamboo (Clump forming) – smaller, clump-forming bamboos with an upright habit, smaller leaves and thinner stems. Native to woodland areas at high altitudes across Asia, they are shade tolerant and extremely hardy. Growing from 1.5 to 4 metres tall, they also relish full sun and are suitable for growing in containers.
Phyllostachys Bamboo (Running) – tall-growing bamboos which are hardy and unfussy, happy in either full sun or dappled shade. Great as a tropical specimen border plant, their thick highly ornate canes also make them perfect for screening/hedging and cutting to stake and support other plants. With an ultimate height between 3 and 6 metres, Phyllostachys varieties include the popular black bamboo and golden bamboo.
Pleioblastus (Running) – a dwarf but spreading bamboo with slender canes bearing several leafy branches at each node. Most have a carpet-forming growth habit, perfect for using as a ground cover plant, in a Japanese themed garden or even for bonsai.
Sasa (Running) – strong, spreading root system that is useful for stabilising banks and slopes or cut back annually and used as a groundcover plant. The variegated Sasa Veitchii has a particularly tropical appearance and tolerates being pruned or trimmed back hard each year.
Use of Bamboo
Small bamboos make ideal container plants grown in a large pot in a loam-based potting compost. It should be borne in mind, particularly for running varieties, that this restriction on their growing environment will necessitate feeding and watering, potentially regularly during the summer depending on the level of precipitation. Running varieties may be grown in larger containers but also need to be divided and repotted at least every couple of years to prevent them from breaking out of their enforced surroundings. We recommend the polished ebony stems and sun-loving habit of Phyllostachys Nigra (RHS AGM) or the arching clumps and leafy canes of Fargesia Murieliae for container growing, especially on a terrace where the rustling and swaying becomes more mesmerising.
Most bamboos, especially running varieties, make a superb windbreak, hedge or screen, to block out your noisy neighbours, hide an unsightly building or simply provide some privacy. Rhizomes can be channelled in a specified direction by sinking concrete slabs or high density polythene either side of the plant. The best one to choose depends on the desired height of hedge, foliage and culm colour you’re looking for. Fargesia planted close together form a dense hedge (Fargesia Nitida is particularly effective), whilst Sasa creates a screen with large, tropical looking leaves and Phyllostachys is best for taller screening.
Fargesia are very well-behaved clump-formers growing to a small or medium height, making them ideal for the smaller garden or creating a medium height privacy screen, whilst spreading varieties with their mass of foliage and character can add a tropical, jungle feel to large gardens if left to meander slightly via their underground rhizomes. Taller varieties can also be used as specimen plants in the middle of a lawn or border to create an ornamental focal point
Containment of Running Bamboos
Keeping running varieties under control and attractive is relatively easy if planting instructions are followed carefully and routine maintenance is undertaken. However, bad experiences of some gardeners with running bamboos does merit a word of caution – they can become invasive, unsightly and spread beyond their bounds if left unrestricted and unchecked. A physical constraining barrier and/or root pruning will keep your running bamboo looking beautiful and restrict it to its designated space
Planting your running bamboo inside a properly installed physical constraining barrier will prevent it from spreading through beds and borders. When planting, dig a trench of at least 60cm (2 foot), but ideally 120cm (4 foot) and line the sides with root barrier fabric, high density polythene (HDPE), industrial linoleum available from builders merchants, or solid materials such as paving slabs, corrugated iron sheets or pre-cast concrete drain sections. The barrier should stick out at least 7.5cm (3 inches) above soil level (best disguised with decorative mulch or stone) to prevent the bamboo stems arching over the top. Avoid loose soil or air pockets next to the barrier by tightly compacting the soil once your bamboo has been planted, otherwise it may go deeper than you want and potentially under the barrier.
Checking for unwelcome, spreading rhizomes and root pruning if required is the next option. Root pruning should be done bi-annually in spring and autumn for running bamboos. Root pruning involves working around the bamboo with a sharp spade, driving it into the ground and removing any rhizomes outside of the area where you’d like the bamboo to grow. As rhizomes are usually very small-rooted and prefer to grow in loose topsoil 5-15cm (2-5 inches) beneath the surface, this should be a straightforward exercise. Small segments of rhizomes can rejuvenate, so be thorough. To make root pruning easier, maintain a shallow trench with a depth and width of 25-30cm (8-12 inches) around the bamboo, or at least along the edge where it is adjacent to a lawn or path. Check for creeping rhizomes a couple of times in the late summer and early autumn to see if any of them have tried to cross the trench; if so, remove them. If a trench is impractical for the planting environment, it can be filled with a loose media, such as sand, which is easy to dig into for root cutting
Planting within physical barriers and root-pruning is not normally necessary for clump-forming bamboos, although lifting and dividing every other year is encouraged (covered further on in this article).
Bamboos are suitable for planting all year round, although if you have a particularly cold, exposed garden planting outdoors sufficiently early to allow the bamboo to become established and harden off prior to their first winter is recommended. Bamboos are not fussy, tolerating most soil types, but generally grow best in a moderately acidic, well-drained, loamy soil in a sheltered spot. If your soil is very heavy, add extra organic material when planting and mulch more heavily. Dig the planting hole 1.5 to 2 times the width and depth of the bamboo root mass and work compost or manure into the soil surrounding the hole. Leave a generous layer of compost at the bottom of the hole so that the rootball sits slightly lower than the original depth, with 2-3cm (1 inch) of soil covering the original surface. By building in compost and organic matter you will give your new plant an initial nutrient boost, whilst also improving the drainage around the roots.
Firm the ground back down well with your boot once backfilling is complete, being careful not to damage the young rhizomes, water thoroughly, then mulch with more compost, grass, hay, leafmould or manure. Protect smaller bamboos from overexposure to the hot sun, particularly if planting shade lovers such as Fargesia in the height of a hot summer. If container growing your bamboo, use a loam-based potting compost and incorporate slow release fertiliser and water retaining gel. Bamboos over 4.5 metres (15 feet) tall planted in an exposed location may need to be staked or guyed for the first couple of years until the root mass becomes well anchored. This will prevent strong winds from uprooting them, or damaging new shoots and culms.
Watering, Feeding and Pruning
Bamboos require frequent and liberal watering when first planted to become established, providing the water is allowed to drain away and the bamboo does not get wet feet. Clump-forming varieties also respond well to feeding, although for more vigorous running specimens this is not normally needed. If you do choose to feed your bamboo, use general purpose plant food or a high nitrogen grass or lawn fertiliser. Apply once in early spring and again in the summer to match the two main growth seasons of bamboo.
Dead, damaged, weak, unattractive and spindly canes should be cut right back to the ground with loppers or secateurs in spring. Fallen leaves, grass cuttings and other debris is best removed from the base of the clumps at the same time. Make your secateur cuts just above a node, so as not to leave a stub that will die back and look unsightly. You may also wish to remove some of the foliage from the lower part of the canes to show your bamboo plants off at their best, preferably using secateurs to cut as close to the main cane as possible or, alternatively, using a swift, snapping motion wearing gloves.
Bamboo in containers require more care because it makes them more susceptible to environmental stress. They are more sensitive to heat and cold, strong winds tip them over, and the restricted root space allows them to dehydrate quickly. They should be watered regularly – every other day in the height of the summer, ensuring that the pot drains well – and protected from frost and ice in the winter.
Dividing your Bamboo Clumps
The best time to lift and divide clumps is mid-spring, before the main growing season. In order to hydrate the plant and reduce the risk of transplant shock, water your bamboo thoroughly the night before you plan to divide. Gently loosen the soil around the clump with a fork, being careful not to damage any of the rhizomes below ground, then gently life them out of the ground. Shake excess soil from the root ball, rinse with water to reveal the bamboo root system and inspect the rhizomes for natural points of division.
Depending on the amount of crowding in the ground or pot, the size of the pot and the number of divisions desired, split the rhizomes into two, three or four sections using a saw, axe or mattock. Any old, rotten or otherwise damaged roots should be discarded to discourage fungal infection and encourage healthy growth. One of the divided sections is best planted back in the original garden location or container, whilst others can be used elsewhere in the garden (following the planting instructions above). When starting from a new planting or small plant division, you can expect to see new shoots grow only slightly taller than the previous year canes. If you prefer to dispose of the extra rhizome sections, allow them to dry out and die before discarding in the compost pile, otherwise they may set root in the nutrient-rich environment of your compost heap!