Mr. Culp might notice a tall, fall-blooming aster or Joe Pye weed (Eutrochium purpureum) that flopped, reminding him that Sedum Autumn Joy or tall garden phlox (Phlox paniculata) had splayed open at their earlier bloom times, too. His note to self on pruning them: “Chelsea Chop.”
Plants so designated will be cut back by a third to a half late next May or early in June. (The technique’s name was coined because its timing coincides with the Royal Horticultural Society’s Chelsea Flower Show, in England.) This will delay bloom time slightly, but promote shorter, sturdier stems.
Also noted: Which plants really worked? “Plant more of those; you work with what worked,” he said. It’s an obvious takeaway, he acknowledged, but one that we often fail to act on if it isn’t duly recorded, and corresponding plant orders placed.
But most of what he looks for is subtler, requiring a practiced eye — opportunities to enrich the fall garden, for example, by building it around a dominant leaf color borrowed from the changing canopy trees. Adding Amsonia to the perennial layer, with its late-season yellow foliage, could provide a link to the changing color of the Princeton Sentry Ginkgo trees above, an all-male cultivar selected for its narrow, conical crowns and lack of nasty-smelling fruit.
Source : https://www.nytimes.com/2021/10/20/realestate/take-a-walk-in-the-garden-before-its-too-late.html225