Chelsea Chop: Control Height & Extend Bloom Time
Do you have any taller flowers that either get too tall to visually fit in or are prone to flopping later in the summer? If so, you might want to consider using the Chelsea Chop pruning technique to control their height and encourage a lower/bushier form. The name comes from the Chelsea flower show in London, which takes place in late May and is the approximate time gardeners do this there. In North Carolina, where it is warmer than London, I usually start to consider this around the beginning of May.
The technique involves cutting off the top 1/3 to 1/2 of each plant to shorten it…although I will often take off as much as 2/3 for really tall plants like Joe Pye Weed. Besides immediately reducing it’s height, this has a number of effects on the plant. First, it forces the plant to use up some of the energy stored in it’s roots to produce new growth, which ultimately results in a shorter plant than if otherwise left unpruned. Second, it results in a bushier form. When it’s stems are cut, the plant puts out new stems at each of the remaining leaf axils (where the leaves come out from the stem) and sprouts new stems from the base of the plant. Each stem that is cut thereby results in several new stems and a form that is wider than before pruning. Third, since it has more stems and fewer leaves per stem, it’s flowers will be smaller but larger in quantity. Lastly, forcing the plant the plant to regrow it’s foliage delays it’s bloom time by several weeks. For perennials that have a short bloom time relative to annuals (a few weeks vs a whole season) , this can be used to extend the overall bloom time for the plant by pruning only part of the plant (i.e. part of the plant blooms at the normal time, part blooms later).
What flowers can you apply this to? Generally, I find it works best for taller summer/early fall blooming perennials…Joe Pye Weed (Eutrochium spp.), Coneflowers (Echinacea spp.), Phlox (Phlox spp.), Goldenrod (Solidago spp.), Black-Eyed Susans (Rudbeckia spp.) etc. If you are in doubt or are trying it with something else beyond the above, a simple google search should give you plenty of information on whether it works for the plant in question.
