Lavender plants can bloom for more than 20 years if they are pruned once a year, according to multi-award-winning garden writer Val Bourne at Hopes Grove Nurseries. Leaving the plants unpruned shortens their lifespan to about five years.
Why pruning matters
Bourne said, “If you leave it untended, you’ll only get five years because the plant will lose vigour.” In contrast, annual pruning helps lavender “live for over twenty years and possibly even longer”.
Unpruned lavender can become straggly and leggy, sprawling open to reveal bare branches with few flowers. Once this stage is reached, the plants are difficult to rejuvenate because they rarely respond to very hard pruning.
When to prune
English lavenders “need to cut back in late summer”, before cold weather arrives. This encourages “a dome of new foliage to develop” by early autumn, which protects the plant in cold weather.
Bourne cautioned, “In severe winters, this dome of foliage may get shabby, so you may need another trim in late spring. Wait until the fear of cold weather has passed. April’s normally the best time if you need to tidy it up again.”
Pruning in October
If lavender has not been pruned by October, experts at British Garden Centres advise a light tidy-up as soon as possible. They instructed, “Remove all the old flower stems and trim back about 2cm of the current year’s green growth to keep the plant compact and mounded, but don’t cut into the old, bare wood.”
Gardeners need to “finish pruning by early to mid-October at the latest so the plant has time to harden off before the first frosts”. If frost is close, “it’s better to wait and do a light tidy in late February or March instead”.
Experts at Gardeners Dream recommend avoiding pruning in October altogether. They said, “If you cut back your lavender now, the freshly cut stems will be vulnerable to frost, which could kill your plant altogether. Your lavender can wait until springtime to be pruned to keep it well protected in the cold weather.”
How to prune
Using clean, sharp secateurs or hand shears, trim the whole plant back by 2.5 to 5cm. Lavender thrives when pruned fairly hard, but never cut back into old wood, as most plants will not regrow from it. Once lavender has become heavily woody, it rarely returns to its original compact shape, so always leave some healthy green growth for the plant to regenerate from.
