Ask Monty

QWhen is the best time to repot cacti and what is the best compost to use? T Dale, N Yorks

ACacti need repotting when the roots are showing through the bottom of the pot. The best time for this is in spring. Desert cacti need lime-free compost with plenty of grit or sand. I use a coir-based compost.

QI have taken over a boundary hedge of hawthorn and holly which is being smothered by ivy. How can I get rid of the ivy and allow the hedge to recover? Philip Whitehead, Bucks

AIvy obscures light so that its host cannot photosynthesise. However, if the ivy is cleared, hosts can recover quickly. Cut the ivy at the base and pull out the top growth from the hedge. This is good warming work on a winter’s day!

QI bought a snowdrop tree and the instructions said the flowers would bloom first on the bare branches. This did not happen and the tree went into leaf. Now the branches are bare again. Can I expect flowers? Molly Van Cleemput, Northampton

AHalesia carolina produces white blooms that hang from the branches in spring, usually just before the foliage appears. It likes neutral to acidic soil in light shade and must not be allowed to dry out, although it needs good drainage. It can take a few years to start flowering, so I suggest patience. Write to Monty Don at Weekend, Daily Mail, 2 Derry Street, London W8 5TT or email monty.don@dailymail.co.uk. Please include your full name and address. We regret Monty can’t reply to letters personally.