How to Prune Mucronate Penstemon


Mucronate penstemon is a variety of Penstemon pachyphyllus that is native to Utah, Colorado and Wyoming. This perennial plant can add to a natural-looking landscape design with its attractive, five-foot tall flower spikes during the summer months. It is sometimes called "thickleaf beardtongue," but it is slightly different from another penstemon with the same common name and is not as widespread as its relative plant. You can keep this plant looking tidy and help it to produce a profusion of lovely flower spikes in summer by keeping it pruned twice each year, in spring and fall.

Pruning Mucronate Penstemon

Step 1

Prune your Mucronate penstemon in spring after your final spring frost (usually April or May) by cutting off old flower spikes where they connect to the plant's main stem. Wait until you see new growth starting before you prune. You might be able to salvage some seeds from the flower spikes if you shake them over newspaper. If you want more plants to naturalize in your garden, scatter any seeds you find in the area where you want them to grow.

Step 2

Cut off last year's foliage to its base with your clippers, taking care that you do not damage the plant's main stem. If you don't see any new growth, prune old foliage only halfway to its base.

Step 3

Prune your Mucronate penstemon again in fall by reducing the plant to about one third its size. Cut all stems and branches down one third of the way to the plant's main stalk. It's important not to prune it more than one third because the plant needs some foliage in the winter to protect it from freezing temperatures.

Step 4

Weed out any unwanted plants in this penstemon's environment after you perform its fall pruning to reduce competition for water and soil nutrients.

Step 5

Control grasshoppers if they are damaging your plant by hand picking or applying a pesticide.

Things You'll Need

  • Garden clippers
  • Loppers


  • USDA
  • Sagebud
  • Pruning penstemons
Keywords: Mucronate penstemon, Penstemon pachyphyllus, native plants

About this Author

Barbara Fahs lives on Hawaii island, where she has created Hi'iaka's Healing Herb Garden. Fahs wrote "Super Simple Guide to Creating Hawaiian Gardens" and has been a professional writer since 1984. She contributes to "Big Island Weekly," "Ke Ola" magazine and various websites. She earned her Bachelor of Arts at University of California, Santa Barbara and her Master of Arts from San Jose State University.