Trimming Summer Perennials

Many of your perennial plants would benefit from a little bit of maintenance, especially at this time of year. Deadheading, shearing or cutback of certain perennials in early summer is helpful in refreshing tired foliage and encouraging rebloom of spring and early summer bloomers.

You may notice that many of the plants listed appear on both lists.  Begin the season with deadheading and move to shearing later in the plants development to get your garden bed cleaned up efficiently.


Deadheading is the act of cutting off or trimming individual spent flowers to remove spent blooms that may detract from overall appearance and encourage continuous bloom. While keeping spent flowers that turn into seed heads can be helpful for birds, some plants either do not create seeds that are overly attractive to wildlife or with deadheading, they can continue to bloom through the summer and at the tail end of summer, can go to seed. This task is usually done with pruners or trimmers. It can be a labor-intensive task requiring regular performance (i.e. a weekly task).

Common plants that bloom longer with deadheading:

  • Leucanthemum| Shasta daisy
  • Agastache| anise hyssop
  • Echinacea | coneflower
  • Monarda | beebalm
  • Rudbeckia | black-eyed Susan
  • Coreopsis | tickseed
  • Gaura| bee blossom
  • Heuchera | coral bells
  • Asclepias | milkweed
  • Penstemon | beardtongue
  • Phlox | garden phlox
  • Scabiosa | pincushion flower

Shearing is a different application for woody plants than herbaceous perennials. Focusing on herbaceous perennials in this definition, shearing is the act of cutting back a large mass of the plant material in one fell swoop. This is done to rejuvenate the plant and is most effective for plants that grow new shoots from their base each year.

After the plant is done with its main first flush of blooming for the season and is developing seed heads with the foliage beginning to look tired, grab a fistful of the plant material and cut it back by 1/2, or in some cases, take the foliage stalk and cut all the way to the base. This is especially useful if the plants have already opened up and are sprawling and reflushing from the center which is common in Geraniums, Salvia, Achillea, Nepeta, and Tradescantia.

Common plants that will rebloom with shearing:

  • Nepeta| catmint
  • Salvia | garden sage
  • Leucanthemum | shasta daisy
  • Rudbeckia | black-eyed susan
  • Coreopsis | tickseed
  • Achillea | yarrow
  • Calamintha | calamint
  • Geranium | cranesbill
  • Lavendula | lavender (shearing of flower stems, do not cut to base)
  • Tradescantia | spiderwort
  • Veronica | speedwell
  • Stachys | lamb’s ears
  • Penstemon | beardtongue

Using the two techniques of deadheading and shearing, one can easily refresh tired foliage and provide a longer season of interest for customer enjoyment. It is a great way to maintain a garden for optimal long season of bloom and is a key part in garden maintenance.