Coneflowers on steroids - Ask Extension
Hi, I have planted a bunch of coneflowers over the years, including those pictured here. Normally coneflowers grow to a foot or two-like the ones in t...
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Coneflowers on steroids #874704
Asked June 25, 2024, 8:12 PM EDT
Hi, I have planted a bunch of coneflowers over the years, including those pictured here. Normally coneflowers grow to a foot or two-like the ones in the foreground of the first attachment. But a bunch of these coneflowers have gotten way too big-like 7 feet tall-as shown in the background of the first attachment and in the second attachment. Did I perhaps plant a different variety? Is this what happens when I fail to cut them down in the winter? If I want 1-3-foot coneflowers, should I cut back the 7-footers now? If so, how low should I cut them? Thanks!
Montgomery County Maryland
Expert Response
The reason for the difference in growth is that this is a different species from the Echinacea in front of it. Several species of Echinacea and Rudbeckia have "coneflower" as part of their common name. Rudbeckia are often referred to as Black-eyed Susans, but some go by a coneflower name instead. Based on its stature and foliage shape, the tall plant pictured is Cutleaf Coneflower (Rudbeckia laciniata), a native perennial closely related to the more familiar Black-eyed Susan types commonly grown. It is native, and normally this size. The linked page provides some images of their blooms. If you bought the plant without a botanical name associated with it, or if it was mislabeled by the nursery, then that may explain the mix-up.
While you can probably cut back Cutleaf Coneflower mildly (nothing too drastic, maybe a third of the height at the most) to shorten it and delay bloom a little, it can't really be done this late in the growing season without more dramatically impacting flowering. That pruning technique, sometimes called the "Chelsea Chop" in relation to the timing of London's Chelsea Flower Show, is usually performed in late May, though not all types of perennials benefit from or respond well to it. Otherwise, plan on Cutleaf Coneflower reaching this height and relocate it to a more suitable part of the garden, if you are able. (It not, maybe you can trade it for another plant with a fellow gardener.)
Miri
While you can probably cut back Cutleaf Coneflower mildly (nothing too drastic, maybe a third of the height at the most) to shorten it and delay bloom a little, it can't really be done this late in the growing season without more dramatically impacting flowering. That pruning technique, sometimes called the "Chelsea Chop" in relation to the timing of London's Chelsea Flower Show, is usually performed in late May, though not all types of perennials benefit from or respond well to it. Otherwise, plan on Cutleaf Coneflower reaching this height and relocate it to a more suitable part of the garden, if you are able. (It not, maybe you can trade it for another plant with a fellow gardener.)
Miri
Miri,
Thank you so much - this is really helpful. You are correct that the tall coneflowers are cutleaf. I'd like to transplant them right away because they are taking over our front walk but do I need to wait for cooler weather to transplant?
Thanks again!
Patrick
You're welcome.
Although the plant will probably survive the move now, it will likely wilt a lot and might lose flower buds due to the stress. It would likely recover enough, though, to re-establish well and flower normally next year, if not even later this summer. Otherwise, yes, ideally wait until a window of cooler weather, once the heat wave abates for a day or two at least.
Miri
Although the plant will probably survive the move now, it will likely wilt a lot and might lose flower buds due to the stress. It would likely recover enough, though, to re-establish well and flower normally next year, if not even later this summer. Otherwise, yes, ideally wait until a window of cooler weather, once the heat wave abates for a day or two at least.
Miri
