ASK DIARMUID

QIhave a lovely lilac which is trimmed vigorously after flowering each year. I’m not sure what species it is but it flowers May/ June each year and it has long pinnacles of very scented blossom. However, I don’t think it is pruned correctly as it is very bushy and dense with fewer blossoms than in past years. Can you advise me? Rosemary Lowe

AYouare correct to prune your lilac straight after flowering in June. Lilacs flower on last year’s growth so a later autumn or winter pruning would remove potential flowers for the following spring.

There could be environmental reasons why it didn’t flower so well, ranging from periods of drought to excessive moisture.

Vigorous pruning can encourage lots of leafy growth at the expense of flowers so I recommend a very light pruning next year after flowering and I think you will then see better results.