Do the Chelsea chop and encourage better flowering from your perennials while reducing the need for staking.
This handy technique is so called because it’s always carried out at roughly the time of the RHS Chelsea Flower Show each year – towards the end of May. Cutting back certain perennials at this time of year encourages them to produce denser, sturdier growth in the summer with many more flowers.
It works best on late-flowering perennials, including sedum, phlox, heleniums, echinacea, anthemis and solidago. Never try Chelsea chopping plants which only flower once, such as iris or peonies, or plants with tall spires as the process shortens their height and you won’t get the effect you want.
Choose a dull day, preferably after rain so that the plants are as plump and full of moisture as possible (if the weather is dry, put the job off for a while). Using shears or secateurs, cut the whole plant back hard, reducing the height by at least a third and as much as a half. This may seem dramatic, but it does the plant a lot of good. It encourages growth that is short and sturdy rather than tall and leggy, so plants need less staking. And best of all it encourages the main stems to branch, producing lots more flowering stems and a better display.
Flowering will be delayed by a week or two, so a modification of the technique which is also less drastic is to cut back just half the stems, leaving the rest long. This means the longer stems flower at the usual time, and the ‘chopped’ stems a few weeks later, staggering flowering and extending your display, too. Finish off by watering your plants well, then just sit back and look forward to double the flower power this summer.