Ask Monty

QI have a large calla lily that needs to be moved. When is the best time to do this? Mrs E Woods, Merseyside

ACalla lilies should be moved and divided every five years or so. Do this in autumn or, if yours is to be wintered under cover, in spring before planting out. Dig it up and break off rhizomes, each with a shoot. After a couple of days, replant them in welldug, enriched soil or in a pot of peatfree compost with added garden compost or soil improver.

QI’ve had eucomis in a pot for eight years. I add bone meal and Growmore in spring, then tomato feed in summer. Why was there only one bloom this year? Moon Courquin, Middlesex

AIt needs to be repotted in fresh compost next spring as soon as it starts to regrow, and I suggest doing so every two or three years in future. For now, keep it dry but frost-free all winter. After repotting, water regularly until the autumn, but cut back on the feed.

QEvery plum in our crop this year has a small maggot inside living close to the stone. What are they? Stephen Greenwood, Herts

AThe caterpillar of the plum moth,

Grapholita funebrana, is pink with a brown head and may leave excrement near the plum stone. To control them, put out pheromone traps in May. These attract male moths, which stick to the traps before they have a chance to breed. 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.