Best time to prune lavender or risk ‘replacing the plant altogether’

Lavender is loved for its richly fragrant flowers and aromatic foliage. It is an easy-to-grow shrub that thrives in a sunny spot, in free-draining soil or a container. 

Many varieties are hardy and flower from late spring to summer, with evergreen foliage that is usually silver-grey or green-grey depending on the time of year. 

When it comes to pruning lavender, the Royal Horticultural Society recommends a “trim in the late summer, just after flowering has finished”.

Sean Harkin, team leader of the Herbaceous Ornamental area at RHS Garden Wisley said “it’s really important to keep on top” of lavender by “pruning it or trimming it annually to keep it in shape”. 

Gardeners should “remove any spent flower stalks and about 2.5cm or one inch of leaf growth”. 

Sean added: “It’s really important because we can’t prune into old wood. If we don’t cut it back annually, the plants will get big, leggy and misshapen, and rather than cut them back we’d have to replace them altogether.”

The first step is to “cut off all the old flower stalks”. Sean used shears but secateurs work just as well. 

Once all the flowers are removed, “it’s then a case of going over the whole plant trimming it back into fresh, this year’s growth”. 

When pruning back, gardener’s should “be careful not to go too far into old wood, and to leave some fresh growth on the plant”. The plant should look “compact” and it will be “ready to flower next year”. 

For gardeners looking to add lavender to their outside space, there are a plethora of varieties that grow well in UK gardens. 

Angustifolia, which is more commonly known as “blue ice” is a great choice as it is well-scented and pale purple in colour.