Time for the Chelsea chop

Summer and autumn-flowering plants can benefit from being cut back now. This may seem crazy, since their stems are so young, but there are sound reasons for the treatment.

Known as the Chelsea chop, the technique applies to certain summer and autumnblooming perennials. Plants which respond to the chop include tall phlox, perennial asters, border chrysanthemums and tall sedums.

You can treat suitable plants in three different ways. The simplest is to cut back all stems by a third or even half their length. That will make the plants produce sideshoots

which will carry more flower, usually for longer than on plants left untouched.

The second alternative, if you grow your plants in groups, is to chop some but leave others untouched. That results in a longer flowering period. Plants which have been ‘ chopped’ will grow less tall, so cut the front plants back but leave those behind untouched.

The final, though fiddly, method is to remove some of the stems from each plant. The untouched stems will then flower first, followed by the side- shoots which grew from the shortened stems.

The chop is not suitable for early summer plants such as oriental poppies, herbaceous peonies or aquilegias. Those are best left untouched.