GOLDEN VALLEY, Minn. — The Chelsea chop isn’t a common term used here in the states but it’s all the rage in the UK. It’s a gardening tactic of cutting back perennials in order to control their size and extend the bloom season.
The name Chelsea chop comes from the famous Chelsea Flower Show, which happens every year in the UK and coincides with the right timing to cut back perennials.
There are two main reasons to do the Chelsea chop.
Control size or height: If you have a perennial, like catmint or sedum for example that tends to crowd out its neighbors, cutting it back by about 1/3 now will create a tidier and bushier plant later in the season. This ironweed gets really tall. So again, by cutting it back by 1/3 I can restrict its growth just a bit so it better fits this spot.
Delay or extend flowering: When you give a perennial the Chelsea chop, flowers typically come a couple weeks later in the season than they normally would. So with this phlox, if I cut back 1/3 on some of the plants, but not others, I will end up with an extended bloom season… some that bloom at their regular time, and another round just as those first flowers start to fade.
There are two ways to do this. You can either cut a whole plant back by 1/3, or just cut half the stems back by 1/3. If you do this second method, be sure to deadhead the first flush of flowers to signal to the plant that it’s still time to put energy into the second round of blooms.
Summer and autumn-flowering perennials are typically ideal candidates for the Chelsea chop. Asters, penstemon, rudbeckia, shasta daisy are just a few examples.
One other thing to keep in mind, the Chelsea chop usually results in more flowers, but smaller flowers than a non-chopped plant.
Give it a try!