The Chelsea Chop: my results

I’ve been meaning to try the “Chelsea Chop” for some time but never quite got around to it until this year.

The Chelsea Chop involves cutting down certain herbaceous perennials by a third to a half in late spring (round about Chelsea Flower Show time, hence the name) in order to improve their habit, and delay or  stagger flowering. It’s particularly recommended for taller specimens that are prone to flopping (phlox, for example) and for late summer flowering plants in general.

I thought it could do no harm, so I tried it on the following:



lysimachia (punctata and ephemerum)

aster frikartii Monch

In a way, it was a difficult year to assess the effect because summer was so late in happening that lots of flowering plants came into bloom much later than normal anyway, but of the species I tried the most notable success was probably the nepeta.

I love nepeta. but usually by early July it is an unruly mess flopping all over the place and generally getting in the way. This year, having hacked it back by half at the end of May, it has grown into a much tidier mound without losing a significant amount of flower power, so I will definitely be giving it a spring haircut from now on!

The lysimachia I treated a little differently, pruning down only half the stems in each clump to see if flowering would go on for longer, but I don’t think it made much difference to be honest.

The aster I chopped to try and produce a less straggly plant, but it doesn’t seem to have worked at all and I’ve still had to put in some canes and string for support.

Most interesting to me was the phlox since that is the example very often given as the perfect subject for Chelsea Chopping.

I tried it on a clump of “Prospero”, pruning half the stems down to half their original height and leaving the other half for comparison. Contrary to my expectation, the stems that were left alone seemed to grow stronger than the chopped ones and had much bigger and better flowers on them. They also flowered at almost the same time, so there wasn’t even the advantage of extending the flowering period.

All in all, rather mixed, though as I say, the lateness of the seasons this year may have played a bigger part than I realise – I might give it a whirl next year just to see if I get the same results.


Posted on September 6, 2013, in Techniques and tagged , , , , . Bookmark the permalink. Leave a comment.

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