To prevent flopping, start pruning your perennials now

by Susan Harris
One of the best-selling garden books of all time introduced us to the notion of pruning perennials. The book is The Well-Tended Perennial Garden by Tracy diSabato-Aust, published in 1998.  Among many other bits of great advice, the author advises boldly hacking back perennials early in the season – now – in order to create shorter, fuller plants that won’t flop over when they reach their full size.

In my garden, the tall perennials get their first haircut in early May, and it’s generally recommended that even the latest-blooming perennials have their last haircut by the end of June.  I play it safe and do it as early as possible, as long as the stems are at least a foot tall.  I simply cut off the top half of each stem.

 

Asters and Sedum 'Autumn Joy' with Grasses in September

Here are the plants I’ve hacked back to good effect in the past and will continue to prune that way:

  • Asters of all types because boy, can they flop!  Especially when they’re in a bit too much shade.
  • Tall Sedums, like ‘Autumn Joy’.  Ditto the problem of shade causing flopping.
  • Garden phlox.
  • Goldenrod.
  • Monarda.
  • Echinacea purpurea (Purple coneflower).

Monarda and Garden Phlox in late July

2 Responses to To prevent flopping, start pruning your perennials now

  1. becky says:

    Good advice; I usually forget to do it til it’s too late (esp my asters!)

    Have a question re phlox? My tall phlox suddenly wilts at times and withers away, sometimes it regenerates itself. Two plants side by side-one is healthy, other comes and goes. ANy ideas? Poss something eating/chewing on the roots? Out of a total of 6 phlox only 1 is affected.

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