Walking through a garden filled with flowers brings me immense joy. As a professional horticulturist, I also applaud the gardeners as I enjoy the fruits of their labor. My gratitude stems from the knowledge of knowing how much effort goes into not only maintaining the blooming brilliance of a summer garden but the planning.
The first flush of summer blooming flowers lights up the garden creating a magnificent sight and then, unfortunately, they fade. Keeping plants robust and repeatedly flowering means the gardener must not only maintain plant health but remove the spent blossoms, too. This is referred to as deadheading. Cutting off dead flowers keeps many plants in a perpetual state of bloom because it prevents the plant from going to seed.
Think of it this way, every plant wants to produce seeds to perpetuate the species and if the flowers are continually removed from healthy plants, then the plant will continue to produce more flowers.
As I write this, I am thinking of the thousands of hours I have spent removing spent blossoms from the gardens I have designed and tended. I also remember the beautiful gardens they grew to be because of the time spent, almost daily, deadheading.
Modern varieties of ageratum, vinca (Cartharanthus), several types of Petunia and annual geranium (Pelargonium), plus Penta, Begonia, Callibrachoa, Verbena, Lantana spp. and even the Zahara and Profusion series of Zinnia elegans are self-cleaning plants. This means the flowers die and the plant continues to grow and produce more flowers.
Still, there are many annual bedding plants which require deadheading to keep blooming. Marigold (Tagetes), pansy (Viola), sage (Salvia), snapdragons (Antirrhinum), sunflowers (Helianthus), Cosmos, Zinnia spp. plus our native bleeding heart (Dicentra eximia) will continue to bloom until frost with regular deadheading. Some plants are grown for their foliage, like Coleus sp., and their flowers are removed to not detract from the ornamental leaves.
Deadheading spent flowers redirects the energy of a plant to growing roots and shoots and in the case of Coleus, encourages the plant to continue growing colorful leaves.
In addition to annuals, many perennial herbaceous plants will rebloom with deadheading. Flowers atop stalks like yarrow (Achillea), Shasta daisy (Leucanthemum), bee balm (Monarda), butterfly weed (Asclepias), false sunflower (Heliopsis), tickseed (Coreopsis), blanket flower (Gaillardia), pinks (Dianthus) and garden phlox (Phlox paniculata) will continue to bloom after the primary flower has bloomed and been removed. New flowers will emerge from the leaf axils along the stalks if the top flower is cut off just above the first leaf.
When flowers bloom along spikes that emerge from low growing foliage – like a rosette – the plant can still be tricked into reblooming. This is all about timing, because the flower spike must be removed when it is only 70% bloomed out.
I remind myself that losing a few blossoms will reap rewards with even more flowers later so I grit my teeth and make the cut. Herbaceous perennials which benefit from this timing of deadheading are perennial sage (Salvia), spiked speedwell (Veronica), Culver’s root (Veronicastrum), and Penstemon spp. to name a few.
Repeat blooming roses such as hybrid T, hybrid perpetual, floribunda and grandiflora types should have their spent blooms removed regularly for them to continue blooming until frost. Removing the spent flowers on the verge of the petals dropping will also keep Botrytis cinerea at bay. Once infected, this fungal disease will prevent flower buds from opening by causing brown decay.
Another step I take is to keep my rose beds free of rose petals to prevent the fungal spores from thriving on top of the mulch and then splashing up on to the flower buds. To prevent moving a disease from one plant to another unintentionally, I always sterilize my hand pruner between plants. I do this by spraying them with 70% isopropyl rubbing alcohol; just remember to direct the spray away from all plants to prevent damage from the spray drift.
While deadheading can initiate more blooms, there are many instances where it improves the appearance of the plant. I deadhead plants which have finished blooming like peonies (Paeonia), lungwort (Pulmonaria), coralbells (Heuchera), lady’s mantle (Alchemilla) and obedient plant (Physostegia), Iris and Hibiscus spp. for this very reason. I remove the entire flower stalk by pruning it off as low as possible. In all cases, I make all pruning cuts at an angle to facilitate water runoff during a rain event to keep the tip dry and thus prevent disease.
Finally, there are a few plants that if cut back mid-growing season, will grow and rebloom profusely later in the season. In zone 7, I cut back the entire plant of germander (Teucrium), catmint (Nepeta), thyme (Thymus), wandflowers (Gaura) and Geranium spp. (not the showy Pelargonium grown as annuals) to 4” in early July.
I then apply an organic fertilizer per the product’s instructions and within a few weeks, I am enjoying a full flush of flowers once again. After all, I can’t think of anyone who doesn’t enjoy strolling through a garden filled with flowers and deadheading regularly will have your garden blooming until frost.
Happy Gardening!
Peggy
