Although bamboos are attractive and often sought-after garden plants, some species spread rapidly by means of rhizomes and can become invasive. Digging out rampant clumps can be difficult, but there are other control options.
Why is it a problem?
Bamboo is mainly a problem in borders.
Some bamboos are strong-growing and spread rapidly by means of rhizomes and so may become invasive. Digging out invasive clumps can be extremely difficult, especially on heavier soils.
Invasive bamboos include: Arundinaria, Bashania, Chimonobambusa, Clavinodum, Hibanobambusa, Indocalamus, Phyllostachys, Pleioblastus, Pseudosasa, Sasa, Sasaella, Sasamorpha, Semiarundinaria, Sinobambusa, Yushania.
Control
Cultural/Organic Methods
If any shoots extend beyond their limits, you can sever the connecting rhizomes with a sharp mattock or similar tool, then remove the unwanted shoots using a strong garden fork. The fringes of larger clumps can even be rotovated.
Growth can also be contained with a physical barrier - either solid or fabric. Suitable solid materials include paving slabs, corrugated iron sheets and pre-cast concrete drain sections. Fabric materials include specialist root barrier fabrics and industrial linoleum (not domestic lino) available from builders' merchants. Fabric ends should be overlapped by at least 30cm (1ft) and bonded with an appropriate mastic. Butyl pond liners are not suitable. The barrier should be at least 60cm (2ft) deep, and ideally 1.2m (4ft). It should protrude at least 7.5cm (3in) above soil level as bamboo rhizomes are capable of arching over a low barrier.
Chemical Controls
Sodium chlorate
In the spring this soil- and foliage- acting weedkiller can be applied with a watering can and dribble bar to young shoots after having the old canes cut back in late winter. However, surrounding garden plants and lawns could be harmed if their roots extend into the treated area or if the site is sloping, as sodium chlorate is fairly soluble and can leach through the soil following heavy rain.
Glyphosate
A glyphosate-based weedkiller can be applied to the foliage when the bamboo is in active growth in mid-summer. There is no risk to underlying roots of garden plants, but foliage of surrounding plants can be damaged by spray drift. In order to kill only part of a bamboo clump or where individual shoots of bamboo grow through other garden plants trace back the rhizome and sever at the point of origin. Protect surrounding plants with bin liners or polythene then spot treat the bamboo. Once the weedkiller is dry the protective polythene can be removed.
Where the use of sprays on tall clumps of bamboo poses a serious risk to nearby garden plants, try cutting down the canes to soil level in late winter. Then apply the weedkiller with a watering can and dribble bar, or low pressure sprayer, to the young growth in late spring or early summer when new growth is well advanced. Repeat the treatment as necessary until there is no further regrowth.
If you just wish to kill a section of a plant, sever the roots and rhizomes from the part of the clump you want to keep and then apply weedkilller to the other part.