Deadhead Now! (Or Don’t)
Kristin Schleiter is the NYBG’s Associate Vice President of Outdoor Gardens and Senior Curator. She oversees the wonderful gardening team that keeps our flowering gardens looking top notch, curates the herbaceous gardens and collections, and manages the curator of woody plants. She lives and gardens in Fairfield, CT.
Deadheading or removing spent flowers is an important task in the late summer garden. Simply follow the stem under a spent flower down to the larger stem it branches off from and clip it off. Deadheading has several benefits, the most obvious being that it can make your garden look neater. Removing the spent flowers can also push side buds to break, yielding a thicker and lusher plant. Removing the spent flowers and thus the potential seed from the plant can make many plants continue to bloom in an effort to create seed and to propagate themselves. Of course, the extra benefit of removing seed is that you are also removing all the work you would have to do weeding out unwanted seedlings!
Some perennials that can be very heavy seeders are garden phlox (Phlox paniculata), hosta, columbine, many of the different decorative onions (Allium) and black-eyed Susan (there are lots of different Rudbeckia and most are heavy seeders if the conditions are right). Sometimes, as with the Rudbeckia, there is a trade off. You can remove the seeds to be sure of less work or you can leave them and enjoy the goldfinches that will sit on the seed heads and have a lovely lunch. Many seedheads can also look lovely into the winter, providing architecture in your garden long after the blossoms have faded. Of course, letting plants seed on their own can be a wonderful way to increase the size of your garden without spending any money!
Some annuals that seed around are pansies, flowering tobaccos, Verbena bonariensis, and cleome. I always enjoy free plants and these guys have a knack for seeding themselves into incredibly charming places. Just keep an eye out for seedlings and edit them if they are in the way or crowding other plants.
Gardening is an art and deciding whether to deadhead or leave seedheads in place definitely helps to set the style of your garden. There is no wrong or right—just what you prefer.