What is Deadheading?
Deadheading is the simple act of removing spent (dying) flower heads from annuals, biennials, perennials, and flowering shrubs. This process tricks the plant into continuing to produce flowers instead of beginning to produce seeds as part of the normal plant lifecycle.
Reasons for Deadheading
For aesthetics
In most cases, dead flowers are not attractive. Plants with dead flowers can detract from an otherwise beautiful landscape.
To promote the health of the plant
Forming seeds can dominate the plant's growth activity at the expense of its roots and lead to its early death. Annuals, especially, have one goal in life--to flower and then to produce seeds. When that goal is accomplished, the plant has no reason to continue living. Therefore, it is very important to constantly deadhead most annuals to keep them in bloom.
To extend or repeat bloom time
Perennials and biennials can often be coaxed into flowering for a longer period of time if they are not allowed to go to seed.
To prevent self-sowing of seeds
Plants that are aggressive seed producers can be kept in check by deadheading to prevent them from forming seeds.
Considerations for Deadheading
Some plants form interesting seed heads and are best left alone. A shrub that develops berries for birds or for flower arranging, a perennial such as Sedum 'Autumn Joy' that provides winter interest, or any plant that has seeds that can be used for drying (such as Nigella) need not be deadheaded.
While it is true that deadheading consumes a great deal of time (it continues from early spring until a killing frost), the labor is less intensive if it is done regularly.
Generally, how far down to cut can be determined by examining the growth habit of the plant. If new flower buds are present, the cut is made to the top-most one. If the flower is not on a bare stalk, the cut is made to a leaf. If it is on a bare stalk, the cut is made to the basal rosette (the grouping of leaves at the base of the plant). If, as is the case with daylilies, after each individual flower has been removed, there is nothing left but a stick, that stick is then cut down to the base.
Some plants present special problems. Those that form masses of flowers (like Coreopsis) can be sheared. Plants that have flower spikes that bloom from the bottom up are best treated by deadheading when about 70% of the spike is going to seed.
Keep in mind that if biennials are deadheaded, seed will not be produced and the plant will not appear the following year.
Following is a general listing of plants that can be deadheaded, with guidelines for deadheading specific plants:
Annuals to Deadhead
- Alyssum: Clip back long stems
- Cleome: Pinch off seed capsules if you don't want reseeding
- Cockscomb
- Coleus: Many gardeners pinch out flower stalks as soon as they appear
- Cosmos: Pinch back hard to keep them looking attractive
- Geranium
- Lobelia: Prune back long stems mid summer
- Marigold
- Nasturtium
- Nicotiana: Do occasionally; it keeps them looking attractive
- Pansy: Clip long stems in mid-summer
- Periwinkle: Only cut long stems
- Petunia: Pinch out flowers, long stems in mid summer
- Pinks or Dianthus
- Salvia
- Snapdragon
- Verbena
- Zinnia
Perennials to Deadhead
- Bleeding Heart: encourages longer bloom
- Bulbs: allow leaves to die naturally- do not remove
- Campanula: for rebloom
- Columbine: prevents reseeding
- Coralbells: for rebloom
- Coreopsis: for rebloom; appearance
- Dames Rocket: for rebloom
- Daylily: for appearance
- Delphinium: for rebloom
- Fernleaf Yarrow: for rebloom; prevent reseeding
- Flax: for rebloom
- Hosta: for appearance
- Lupine: for rebloom; appearance
- Marguerite Daisy: for rebloom
- Peony: for appearance
- Phlox: for rebloom; prevent reseeding
- Salvia: for rebloom and appearance; can bring back whole plant
- Shasta Daisy: for rebloom
- Veronica: for rebloom
Plants That Self-Deadhead
- Fibrous Begonia
- Impatiens
- Moss Rose (portulaca)
Perennials To Leave Through The Winter
- Aster
- Astilbe
- Common Yarrow
- Coneflower
- Liatris
- Oriental Poppy
- Rudbeckia: (will reseed profusely)
- Sedum
