I’m not sure the exact history of the term “deadheading“, but it is an often discussed topic in the garden center so we thought we’d expand on it a little and offer a few pointers. Deadheading means removing spent blooms. The is done by gardeners for a few reasons. One is to clean up older dried flowers, mostly for aesthetics. Some plants just look better when their old dried up flowers are removed.
To take this topic a little deeper and beyond just aesthetics – the other reason to dead head has to do with the birds and the bees – literally! If you think about it, the goal of most plants is to reproduce. To do this, many of them produce a beautiful flower to attract pollinators. After pollinated typically a seed is formed inside the fruit. It is thought of the a plant uses a certain amount of energy to make the fruit. Removing the “spent” or old flowers will cause the plant to put more energy into photosynthesizing or making energy that will be sent top the roots to make the plant stronger in the future. Some plants that continue to flower freely and the general thought here is if you deadhead the plant, you can trick it into continuing to produces flowers – which is not the ultimate goal of the plant, but humans like to see flowers. Pollinators like them as well!
So those are some of the benefits of deadheading. There are a few other things to consider. Some people subscribe to the idea if you leave the seeds on your perennials, certain birds and wildlife will appreciate eating them later in the season. So there maybe be some ecological benefits of leaving seeds on many plants. The value of the seeds vary from plant to plant. More on that below. The other reason some people prefer not to deadhead certain plants – mostly perennials and shrubs is because of aesthetics. Some people like the look of certain plants that have attractive fruit or seeds. This is a topic that can be debated in some plants, but not others. For example most people love the look of fruit Viburnums, Winterberry, etc. Other plants have great looking dried flowers such as hydrangeas, etc. Then there are plants like Sedum, Coneflower, Black-Eyed-Susan or Yarrow that look good for a certain time, but look old and dried out after a while. This is what is debated. Some like that look and others don’t. When in doubt, leave perennial seeds for the birds.
The other reason to remove seeds is to avoid re-seeding. This again is debatable. I have some native Swamp Milkweed in my garden that i did not plant. I leave a small patch of it for butterflies, but I remove the seed pods before they fly all over the yard. I do the same thing for Black Eyed Susan (Rudbeckia), Asters and False Indigo (Baptisia), but I let my Coneflowers (Echinacea) seed freely in my garden. Those are examples of choices I make. I leave my Yarrow, Sedums, Golderods (Solidago) and many others
In addition to deadheading, another technique is in season pruning of perennials. This is often done to prevent or minimize perennials from flopping over and looking empty in the middle. Plants flop after the flowers open because there is more surface area for rain water to land on and water is heavy. Common plants that flop include – Catmint, Salvia, tall Sedums, Montauk Daisies, etc. Typically Salvias and Catmint can be deadheaded while flowering by removing spent blooms. This removes some of the weight and reduces flopping and it helps the plant bloom again since they are continuous bloomers. If this is too tedious to trim only spent blooms and leaving the new buds and flowers, then just trim back the whole plant with electric or hand shears. Because both plants sporadically flower all summer, a hard cut back will remove some flower buds. Just removing the spent blooms is ideal, but time consuming. The hard shearing will delay flowering but create a second “flush”, where the plants bloom more prolifically at one time vs a flower here and there. However, the second flush is never as prolific and colorful as the first one, but still typically worth the effort.
Some plants that bloom later in the summer or fall such as tall Sedums and Montauk Daisies usually benefit from to light trimming before the 4th of July. Simply trimming the plant back by hand or with shears will encourage more and shorter branches, instead of long tall branches that flop when the flowers open. Because they bloom so late a trim will not hurt or delay the plant significantly, unless you do this too late.
Plants that flop such as Delphinium and Peonies are only pruned if you are bringing the flowers into the house to put in a vase. You can remove spent blooms on these. With Delphiniums, it will encourage more flowers. With peonies it will not, but it may mean more stored energy and flowers next year. Both of these plants are notorious floppers. Using stakes for delphiniums and nice peony hoops are the most common solutions. Ask us for more tips and tricks on this.
Here is a list of plants that people commonly dead head or trim in season:
Appearance and repeat blooming – Roses, Spirea
Appearance and/or future strengh, usually not necessary – Lilacs, Rhododendron,
For Appearance and repeat blooms – Salvia, Catmint, Penstemon, Delphinium, Veronica, Coral Bells, Shasta Daisy
Just appearance – Daylilies, Hosta, Peony,
Prevent Re-seeding – Baptisia, Rudbeckia, Coneflower, Aster, Milkweed, Columbine
Annuals typically deadheaded:
Geraniums, Dahlias, Zinnias, Marigolds, Daisies, Salvias, Pansies, Snapdragons, Cosmos, Cleome
Many newer varieties of annuals now are self cleaning and do not require deadheading. Some petunias such as Super or Wave are sterile, meaning they keep flowering there is no need to deadhead.
Plants with fruit that feeds the birds –
Shrubs: Viburnum, Red Twig Dogwood, Winterberry, SummerSweet, Bayberry, Beautyberry, Blueberry, Elderberry, Witch hazel, Button Bush, Sumac, Juniper, Spruces
Perennials, avoid deadheading to feed the birds:
Coneflower, Black Eyed Susan, Yarrow, Sedum, Joe Pye Weed, Coreopsis, Aster, Astilbe, Liatris, Goldenrod
Annuals, avoid deadheading to feed the birds – Cosmos, Sunflowers, Zinnias, Marigolds