Down the Garden Path: Is deadheading scary or beautiful?

Deadheading. Few gardening terms sound so off-putting, especially to novice gardeners. Nonetheless, deadheading can be an important task.

Dead or alive

First, a bit of background. A plant’s primary purpose can be said to be reproduction. The life cycle of most plants runs from seed (or rooted plug/corm/bulb) to leaf growth to flower to pollination and back to seed. The plant may be grown to become food for animals or people, or just to provide beauty for humans’ surroundings, but it needs to create more of itself in order to continue to do these things. How do we as gardeners encourage our plants to continue? We try to plant them in the right place, giving them the conditions in which to thrive: soil type, amount of light, and water. Beyond this, deadheading can contribute the most to the continuation of our plants.

Fooling flowers

Deadheading means the removal of finished flowers (essentially beheading dead flowers), preventing them from setting seed in order to reproduce. As a result, if the plant “figures out” that there’s no seed coming, it makes more flowers in an effort to get those seeds. One benefit, then, of deadheading is to prevent the setting of seed, resulting in control of self-seeding plants so new plants are not popping up everywhere.

I grow nodding pink onion (Allium cernuum) in my garden, and as soon as the flowers are finished, I trim them off, keeping these plants from taking over. However, if you have an area in which you want a plant to spread, let the seeds develop, and let nature take its course. I have annual larkspur (Consolida ajacis) as a filler in a perennial bed. I shake the dried seed pods over the places where I want the new plants next spring.

The most common use for deadheading is to keep plants in continuous bloom. This applies primarily to the annuals with which we fill our summer gardens. It’s easy just to snap off the marigold’s seedpod just below the swollen portion that holds the seeds. For others, cut back the flower stem just above a leaf node; this can encourage branching.

Many perennials only bloom once, so deadheading is mostly done to clean up unsightly dead flowers. Iris stalks should be cut back to their base. Finally, deadheading can double the number of lilac flowers. After they have finished, carefully trim off the developing seed head. If you do it right, there will be twice as many lilac trusses next spring!

Important exception

A note about native plants, however. Many native plants, like coneflowers, should keep their spent flowerheads. They will generally not rebloom, so deadheading will not have any benefit. Additionally, the seeds that are made will provide necessary food for winter birds such as goldfinches. Leaving the dried flowers will provide winter interest as well as overwintering homes for pollinators.

For more information, check out the University of Illinois Extension website at extension.illinois.edu. Also, check out the University of Illinois Extension Horticulture YouTube Channel for videos on other horticulture topics.

Sandy Lentz is a certified Master Gardener volunteer with University of Illinois Extension in DuPage, Kane, and Kendall counties.

Have a question for the Master Gardeners? Residents can contact the Kendall County Master Gardener volunteers on Monday, Wednesday, and Friday from 9 a.m. to 12:30 p.m. by calling 630-553-5823, stopping in at 7775B IL Route 47, Yorkville, or emailing uiemg-kendall@illinois.edu . For helpful hints on what to include in your email, please visit go.illinois.edu/HelpDeskMGdkk.