Cutting back herbaceous perennials in late May – around the time of the Chelsea Flower Show – is a useful trick to improve plants’ flowering performance and longevity. Various perennials benefit from the Chelsea Chop including geraniums, phlox, Sedums (confusingly now called Hylotelephium) and Penstemons. One can cut back by up to half the entire plant, or just cut the front of the clump – I opt for the latter this year, especially as the cold weather earlier this year seems to have delayed everything by a week or two.
Yesterday I cut back various pink-flowering geraniums but couldn’t bear to cut back my blue ones which were alive with bees. I think this variety is Geranium ‘Johnson’s Blue’ – I am pretty sure it isn’t the multi award-winning Geranium Rozanne which is a really fabulous plant, flowering vigorously from May until autumn. Rozanne grows to 60cm tall and has a 5cm blue flower with white centre, and was shortlisted for the Chelsea Plant of the Centenary for the decade 1992-2002, and was the winner of the public vote.
Above: Time to cut back the Buxus...
Now is also the time for cutting back Box (Buxus sempervirens) – in fact the commonly accepted dictum is to clip Buxus on Derby Day (the first weekend of June) although it is acceptable to clip any time during June. The reason for this is to make sure the last frosts have passed, but clipping also strengthens the plant and can protect it from box blight.