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Mr. Smarty Plants - Cutting back perennials in PA

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Monday - July 25, 2011

From: Mohnton, PA
Region: Mid-Atlantic
Topic: Pruning
Title: Cutting back perennials in PA
Answered by: Anne Bossart

QUESTION:

Can you pinch back echinacea in the spring to produce a shorter plant? I have some that get too tall and fall over.

ANSWER:

Yes you can, but not this year.

There are a number of late-summer/fall blooming perennials that can be cut back by half in late spring/early summer.  As a result, they will be shorter and sturdier (less likely to need staking or fall over).  They will also be bushier and more floriferous.

I have had a similar problem in one of my perennial beds and tried it this year on:

Aconitum delphiniifolium (Larkspur-leaf monkshood)

Monarda didyma (Scarlet beebalm)

Phlox paniculata (Fall phlox)

So far, so good ... the monarda is blooming on schedule at a shorter height than usual and the other two seem to be budding.  I am in zone 5 and did it late in May ... you will want to do it a little earlier than that.

Besides these three and your Echinacea purpurea (Eastern purple coneflower), you can also give the same treatment to:

Eupatoriadelphus maculatus (Joe-pye weed)

Physostegia virginiana (Fall obedient plant)

Symphyotrichum oblongifolium (Aromatic aster)

and the tall sedum varieties.

 

From the Image Gallery


Larkspur-leaf monkshood
Aconitum delphiniifolium

Scarlet beebalm
Monarda didyma

Fall phlox
Phlox paniculata

Eastern purple coneflower
Echinacea purpurea

Joe-pye weed
Eupatoriadelphus maculatus

Fall obedient plant
Physostegia virginiana ssp. praemorsa

Aromatic aster
Symphyotrichum oblongifolium

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