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Give your perennials the Chelsea chop27 May 2013
Give your perennials the Chelsea chop this week to double their flower power and help them grow stocky and strong.
This handy technique gets its name from the timing: it's traditionally carried out in the week after the RHS Chelsea Flower Show. It works on any clump-forming perennial, but you'll find it's particularly useful on those which are otherwise a little prone to flopping, like Sedum spectabile, Rudbeckia 'Goldsturm' and Helenium 'Moorheim Beauty'.
Take a sharp pair of secateurs and snip away about half of the top growth, cutting back each stem to a bud. It looks drastic, but the plant responds by sending out twice as many branches – and that means lots more flowers. The new growth also tends to be shorter, so plants are better able to support themselves without the need for staking.
You'll also find the flowers appear later than they usually would, and you can take advantage of this to extend your flowering season by several weeks. Carry out the chop on around half the stems but leave the other half untouched. Flowers appear at the usual time, but just as they're fading the pruned stems burst into bloom, continuing the display well into autumn.