Be A Better Gardener: To Deadhead or Not?

by Thomas Christopher

One thing I’ve always valued about gardening is the strength of its traditions. This has given the craft a continuity that can be very valuable. So many of our gardening tools, for example, reflect the insights and experiences of centuries of gardeners. I remember seeing a photograph of a pruning knife in a book about ancient Roman agricultural tools that was almost identical to the one I carry in my pocket when I am working in my own little orchard. This tool, an evolution of untold generations of experimentation, simply cannot be improved when applied to the task for which it has evolved.

Still, tradition should be regarded with a critical eye lest it perpetuates errors or harmful practices. For instance, the European-trained gardeners at the New York Botanical Garden who trained me when I was a student there in the mid-1970s viewed gardening in the context of an Old World experience. When they were planting out flower seedlings or bulbs, they never kneeled or stooped but rather bent over almost double. This was a practice they enforced among us students as well. When I complained that my back hurt my mentors shrugged and pointed out that I worked faster in this hunchbacked fashion. The world they had come from was one of abundant cheap labor, and if a gardener’s back gave out, he was easily replaced.

What I really came to hate, though, was the emphasis on repetitive, mindless tasks. Deadheading was prominent among these. For those who don’t recognize that word, deadheading is the practice of pinching off from a plant the flowers as they age and wilt. I could understand why such treatment was essential in maintaining a display of annual flowers. An annual is genetically programmed to complete its life cycle in a single growing season, and after it bears seed, the plant falls into a terminal decline. Deadheading annual flowers, by frustrating seed maturation, keeps the plants in bloom much longer.

When I was told, however, that I should deadhead a mature azalea or a field of daffodils, that justification didn’t apply. These plants have a genetically prescribed season of bloom, and when that ends, they stop flowering whether they have set seed or not. When I raised this point, the older gardeners told me that bearing seeds wasted energy that the plant could otherwise devote to growth or save and use to enhance the following year’s flowering.

As the years passed, I grew more suspicious when I couldn’t find any studies that compared the bloom of daffodils or azaleas that were deadheaded to those that were not. I began to suspect that this chore was another survival from the era of cheap labor.

Recently, my suspicions have finally been confirmed by an email from a hero of mine, Dr. Linda Chalker-Scott. Having received a PhD in woody plant physiology with a minor in biochemistry and botany, she’s an associate professor in the Department of Horticulture and Landscape Architecture at Washington State University and an Extension Specialist in Urban Horticulture. She is fa founding member of an online posse known as “The Garden Professors,” a half-dozen scientifically educated university horticulture professors and extension agents who since 2009 have been answering questions and exploding myths with insights drawn from scientifically designed research projects and refereed papers. That may sound dry, but The Garden Professors maintain a sense of humor and a non-hectoring tone even when they are popping your favorite gardening bubble.

I’d done several online searches for any studies concerning the efficacy of deadheading perennials and woody plants and came up dry when I finally directed an inquiry to Dr. Chalker-Scott. Her reply, drawing upon her education in woody plant physiology, was succinct. 

“By the time you are deadheading plants, the seeds have already set. You would have to remove each flower immediately after pollination to conserve those resources. It’s not very practical. Furthermore, removing living parts of the plant will temporarily increase water loss and potentially create portals for pests and disease. Hope that is helpful!”

Indeed it is. My horticultural mentors are mostly gone now, so they won’t be outraged by my late-in-life declaration of freedom. Apprentices of the world, no matter how old, unite!

Be-a-Better-Gardener is a community service of Berkshire Botanical Garden, located in Stockbridge, Mass. Its mission, to provide knowledge of gardening and the environment through a diverse range of classes and programs, informs and inspires thousands of students and visitors each year. Thomas Christopher is a volunteer at Berkshire Botanical Garden and is the author or co-author of more than a dozen books, including Nature into Art and The Gardens of Wave Hill (Timber Press, 2019). He is the 2021 Garden Club of America's National Medalist for Literature, a distinction reserved to recognize those who have left a profound and lasting impact on issues that are most important to the GCA. Christopher’s companion broadcast to this column, Growing Greener, streams on WESUFM.org, Pacifica Radio and NPR and is available at berkshirebotanical.org/growinggreener.