Gardening Perennials Pruning

Forced Perennials: Off With Their Heads!

Question: I have trouble keeping my echinaceas alive. I buy them in full bloom in the spring and they seem to do all right, blooming much of the summer, but the next spring, they just don’t come back. Yet I think I plant them under good conditions—full sun, good soil, good drainage — , fertilize regularly and water as needed. And I live in zone 5, which should be fine. What am I doing wrong?

E. F.

Answer: You’re buying the wrong ones. When spring plant shopping, always prefer echinaceas that are young and healthy, but with only green foliage, not flowers. If you buy echinaceas in spring in full bloom, they’ve been greenhouse-forced: pushed into bloom before their time. This results in weakened, short-lived plants.

Echinaceas or purple coneflowers (Echinacea cvs) normally bloom from mid to late summer into fall. If they’re in bloom in May, they’ve been grown in heated greenhouses under special conditions to push then into early bloom. This is called forcing. It certainly stimulates sales (who doesn’t want to see what colors their garden plants are going to be at purchase time rather than having to wait a few months?), but it weakens the plant. 

While it is blooming, the plant puts on little to no root growth, investing its energy in blooming and preparing for seed production. Thus, it never has time to settle in and get ready for winter. 

Cut flowers and buds from off-season perennials before you plant them. Photo:, montage:

The next time you buy an echinacea in bloom in spring (or indeed any other late-blooming perennial in flower off-season), cut off all the flowers as soon as you get home. Plant it and care for it as you would any other perennial. With its flowers removed, it will move into “settling-in mode” and start to grow deep, solid roots, giving you a tougher plant much more likely to survive. 

In fact, if it tries to flower a second time at the end of the summer, cut those flowers off too. No blooms the first year will give you a well-established tough plant that should bloom for years to come. 

This same technique—removing the first-year blooms of forced perennials—should in fact by applied to all sorts of perennials purchased in full bloom in the spring, but that really shouldn’t be in bloom at that season: rudbeckias, gaillardias, garden phlox, etc. 

Don’t let any perennial bloom before its time, not if you want it to behave as a perennial.

Larry Hodgson is one of Canada’s best-known garden communicators. He has notably been editor-in-chief of HousePlant Magazine, Fleurs, Plantes et Jardins, À Fleur de Pot and Houseplant Forum magazines and is currently the garden correspondent for Le Soleil and radio garden commentator for CKIA-FM Radio. He has written for many garden publications in both the United States and Canada, including Canadian Gardening, Harrowsmith, Horticulture, Fine Gardening and Organic Gardening. He also speaks frequently to horticultural groups throughout Canada and the U.S. His book credits include The Garden Lover’s Guide to Canada, Complete Guide to Houseplants, Making the Most of Shade, Perennials for Every Purpose, Annuals for Every Purpose, and Houseplants for Dummies, as well as nearly 60 other titles in English and French. He is a past president of the Garden Writers Association (now Garden Communicators International) and the winner of the prestigious 2006 Garden Media Promoter Award offered by the Perennial Plant Association. He resides in Quebec City, Quebec, Canada.

3 comments on “Forced Perennials: Off With Their Heads!

  1. One of the more unpleasant jobs on the farm was breaking the flowers off of the daphne to promote fluffier foliar growth.

  2. Do you recommend that for ornamental shrubs as well? For example roses, gardenias?

    • It’s best to remove flowers from any plant that has been forced before you plant it out, including shrubs. I’m sure there are exceptions, but I honestly can’t think of any!

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