June 11, 2026 In Newsletter Articles, Newsletters

The ‘Chelsea Chop’ for Northern Gardens

by Linda Dietrick, Master Gardener

In 2015, I was lucky enough to visit the garden of the well-known Irish garden writer Helen Dillon near Dublin. It was September, and I was amazed to see everything still in lush bloom, including masses of delphiniums. “How do you do it?” I asked.

She smiled and shrugged as if it were no big secret and replied, “Chelsea chop.” That was the first I’d ever heard of it.

Photographer credit: Linda Dietrick Caption: Helen Dillon’s garden near Dublin, September 2015 Helen Dillon’s garden near Dublin, September 2015. Photo: Linda Dietrick

As I learned later, the Chelsea chop is a popular technique that can be used on many herbacious perennials to increase bloom and encourage a more compact shape. It gets its name from when it’s usually performed, the last week in May, when the Royal Horticultural Society’s Chelsea Flower Show takes place.

Using shears or secateurs, the gardener literally chops about one-third off the top of the plant. This delays flowering by 4–6 weeks, but it promotes side branching, shorter internodes, and many more flowers on all the new growing tips that result. Sometimes only half of the plant is chopped, so that some flowers come at the usual time, while others follow later. With tall perennials that tend to flop over, the technique produces shorter, stockier stems that are less likely to need staking.

Of course, our Manitoba spring is about a month behind that of Ireland and England, so the right time for us to do the chop is around Father’s Day. “Father’s Day chop” sounds rather violent, though, so it’s probably best to keep calling it the Chelsea chop.

What perennials can you chop?

The following perennials can benefit from the technique: yarrow (Achillea millefolium), giant hyssop (Agastache foeniculum), delphiniums, purple coneflowers (Echinacea species), Joe Pye weed (Eutrochium maculatum), perennial sunflowers (Helianthus spp.), false sunflower (Heliopsis helianthoides), sedum or stonecrop (Hylotelephium spp.), beebalm (Monarda didyma), wild bergamot (Monarda fistulosa), catmints (Nepeta spp.), garden phlox (Phlox paniculata), black-eyed susan (Rudbeckia hirta), tall cutleaf coneflower (Rudbeckia laciniata), salvias, goldenrods (Solidago and Oligoneuron spp.), asters (Symphyotrichum and Doellingeria spp.), and Culver’s root (Veronicastrum virginicum).

Tall cutleaf coneflower ‘Golden Glow’ can be Chelsea-chopped for sturdiness and more profuse flowering. Photo: Linda Dietrick.Photo: Linda Dietrick

Be warned, however: the Chelsea chop shouldn’t be used on perennials that only produce flowers once each season. If you cut them back, they won’t bloom this year at all. Non-choppable perennials include columbines (Aquilegia spp.), foxgloves (Digitalis spp.), pinks (Dianthus spp.), daylilies (Hemerocallis), peonies, and bulbous plants like lilies. If in doubt, you can check by googling “Can X be Chelsea chopped?”

Gardeners who grow plants as habitat for bees may be concerned about interfering with their natural life cycles. For stem-nesting bees, however, the Chelsea chop can be a good thing. When you create a cut at the top of a stem, you are simply mimicking a browsing animal. And the opening makes it accessible to bees who might later use the dry stems as homes for their larvae.

What NOT to chop

In Manitoba, this includes some leafcutter and carpenter bees. Bee experts advise leaving between 20 and 60 cm of sturdy dry perennial stems standing year round for such bees, who may use them more than once. Just let the fresh new foliage grow up to hide the dead stems. Meanwhile, if you encourage more flowers, that means more pollen and nectar for bees and other pollinators.

I have had good luck using the Chelsea chop on tall yellow cutleaf coneflower (Rudbeckia laciniata), both the straight species and the double cultivar ‘Golden Glow’. Though shade-tolerant, this plant has a tendency to stretch and fall over in shade, so the technique lets me skip staking while enjoying more blooms.

In Tim Evans’ garden, flat-top asters are made more compact and floriferous with the Chelsea chop. Photo: Tim Evans.

Every year, Master Gardener Tim Evans Chelsea-chops the white flat-top asters (Doellingeria umbellata) surrounding a classical statue in one of his flower beds. He actually waits until buds have formed and then cuts the plants down with a hedge trimmer to his desired height. The bloom is delayed by only a week or so, he says, but with the cut-back “they can quadruple in number of flowers.” Tim says he’d also like to use the technique on a patch of New England asters.

Why not try it yourself?