Cutting back perennials to control height

Fri. May. 31, 2019

Click below to listen to my 2 min. Garden Bite radio show:  Cutting back perennials to control height

The city I live in was set to do some reclamation on my streets. I live on a corner and they planned on doing both of them. So the engineer told me that I’d have to take out my butterfly garden plants if I wanted to keep them while they did the work and they’d put soil back for me to replant but their height was too tall.

the ironweed isn’t blooming yet in this photo… it gets taller yet!
Butterfly garden Sept. 2018 – all native plants. The asters are blooming

I was set to remove the plants and put them in my own make-shift nursery, then the project was postponed to next year. Okay, but now I know some of my plants are too tall, plus, as a recent article in Northern Gardener magazine noted, some don’t like the flopover that can happen with tall native plants.

There’s a solution! Staking is one, but it depends on what you use to stake them with!

Curved linking stakes

Another option to lower your late-summer, fall blooming plants is to cut them back.

Lynn Steiner, the author of the article, says when plants are 12 to 18 inches tall, you can prune them to 6 to 10 inches tall. About a third to half their size.

the butterfly garden – this could take some pruning.

While it seems a little risky, it’s not, the plants bounce back bushier, just like I talked about with herbs yesterday. Choose some plants for pruning and hold back on others so you get a mixed height! Often those that are cut back will bloom heavier too! Perennials for cutting back include:

  • Agastache – Anise hyssop
  • Boltonia
  • Turtlehead
  • Purple Coneflower
  • Joe-pye weed
  • Sneezeweed
  • Heliopsis
  • Lobelia – cardinal flower
  • Monarda
  • Phlox – sweet william
  • Garden phlox
  • Obedient plant
  • Black-eyed susans
  • Goldenrod
  • Aster
  • Spiderwort
  • Vervain
  • Ironweed

NOTE: There are some plants you should not prune back, blanket flowers, gentian, false indigos and liatris. I have liatris in my butterfly garden.

I do love this really cool metal piece I bought from a local artist. I could also cut them back and keep them lower but I like to let them go.

A local artist created this piece. I bent it to capture my blackeyed susans when then start to flop over.