Contact John Negus by email address below
Email: amateurgardening@futurenet.com
How and when do I prune my mahonia?
Q I have an old mahonia that needs pruning. How and when should I do this?
Peter Levick (via email)
A Mahonias are best pruned in spring after flowering so now is the right time to do it. They tolerate hard pruning, so if you were thinking of something drastic your plant should take it well, though I would advise caution if this is the first time drastic pruning has been undertaken.
The advice given by the RHS is that ‘old plants usually respond slowly, but satisfactorily, when cut back to a low framework 12-24in (30-60cm) from ground level’, so this is quite feasible. However, if you can spread the process over two years it might take away any risk of the plant struggling to recover.
Aim to prune away no more than one-third to one-half of the plant in the first year. This could be taking some of the older stems back to 12-24in (30-60cm) above ground level, leaving the remaining stems unpruned, or it could be taking height off right across the plant. Or it could be a mixture – perhaps taking one or two stems right back, some back to a point where younger growth has developed lower down, and some taking the tops out of the stems.
The advice I was given as
