Sunday, May 30, 2010

It's June! Get Ready for Fall!

Get ready for fall?  The fast pace of springtime in the garden has just slowed down a bit. Maybe you have even found a few moments to sit and enjoy the rewards of your hard labor and I’m telling you to get ready for fall.  Lest you think I sniffed one too many viburnum carlesii let me explain...I am talking about the pinching of late summer and fall blooming perennials to control height and/or bloom time.

Almost every gardener has heard of pinching back fall-blooming garden mums (chrysanthemum) until July 4th.  But did you know the same basic concept works for other late summer and fall bloomers as well.  Some of the more common perennials that can be pinched back include achillea millefolium (common yarrow), aconitum napellus (monkshood), andenophora liliifolia (lilyleaf ladybells), alcea rosea (hollyhock), aster, boltonia, Echinacea purpurea (purple coneflower), eupatorium (joe-pye weed), helenium (sneezeweed), helianthus (willow-leaved sunflower), heliopsis, hibiscus moscheutos (rose mallow), lobelia cardinalis (cardinal flower), lychnis (rose campion), monarda didyma (beebalm), pervskia atriplicifolia (Russian sage), phlox paniculata (garden phlox), rudbeckia (blackeyed susan), sedum ‘Autumn Joy’, tanacetum parthenium (feverfew), veronicastrum virginicum (culver’s root).  There are many more late-blooming perennials that benefit from shearing.

June is the best time for cutting these perennials back. Shearing off one half to two thirds of the growth will result in a bushier plant, with reduced height and often more flowers, although smaller in size. Pinching back is useful to reduce the need for staking (as seen in the picture on the left) and usually will result in delay of bloom by one or two weeks.  Layering, or shearing back only some of the plants, will result in staggered blooms.  Pinching too late in the season can cause some of the fall bloomers to flower so late that the frost gets the blooms before they have a chance to open. To be safe, pinch no later than July 4th. 

But before you head out with your pruning shears, know your perennial.  I highly recommend two garden books that need to be in every perennial gardener's library:  The Well Tended Perennial Garden by Tracy DiSabato-Aust and The Perennial Care Manual by Nancy J. Ondra.


  1. I forgot to mention I have been pinching my butterfly bushes as well to not only contain the size, but to encourage more bloom.

  2. Thanks for the tips Kathy. I've done this to some of my perennials but you've expanded my thinking in where else I can go with this.