Question: My neighbour's bamboo is encroaching into my garden. It is like an army marching into battle, going across the garden at a fast rate. The irony is that my neighbour has all but got rid of his, realising what a nuisance it is, but he has used chemicals and I garden organically. How can I halt its progress?
Answer: To keep bamboo in its place in the gardens at Wisley, the canes are simply thinned and prevented from spreading by cutting them if they stray from the clump. Use a sharp spade to sever the rhizomes that are extending beyond their allocated space from the parent plant and then a garden fork to remove them.
It is possible to install a root barrier vertically in the soil, as deeply as 1.2m, but at least 60cm (2ft) deep and above the soil. It should protrude at least 7.5cm (3 inches) above soil level as bamboo rhizomes are quite capable of arching over a low barrier: (www.green-tech.co.uk).
If you need to clear the clump completely, digging the whole thing out is the only, hard, but very organic option. The roots are not deep but they are densely packed and it is easy to leave pieces left in the ground which will regrow. Digging out these smaller pieces is comparatively easy but eradicating all evidence of the bamboo may take a couple of years.
Send your questions for the RHS to: email@example.com.
Only a few questions per month can be answered. For further advice on handling problems in your garden, visit www.rhs.org.uk/advice/index.asp.