Foil the Flop
One of the best things about writing this blog is the fantastic ideas and interesting comments you send. I received one last week that got me thinking. The question was "how to prune" native plants as they look great during summer but, now in fall, they are looking messy.
Perennials are such a natural place to start with native plants. Most have flowers that immediately attract bees and butterflies. They are readily available, easy to plant, and less costly than shrubs and trees.
A bed of perennial flowers looks tidy in spring as foliage emerges and fairly neat during summer as stems grow and flowers form. Once blooms start to fade and a wet, windy or cold weather day or two arrives, those perennials can start to look tired. This led to the popular practice of "fall clean-up" in the garden.
Yes, you can easily cut your perennial flowers and grasses back to 6" for a tidier look. As you know, though, there is a big movement to leave native perennials up through winter because seed heads on plants like black-eyed susans (Rudbeckia) and coneflowers (Echinacea purpurea) provide valuable seeds for birds in colder months and beneficial insects over winter in the stems of perennials. Visually, leaving perennials standing also can add interest to your garden in winter. What if you want to be a forward thinking gardener but not have messy looking beds? Here are a couple of ideas. Some we can do now; others are for for spring.
Partial Perennial Pruning
One way to approach this is to cut back the portion of your perennials that are flopping over bed edges and leave the others till spring. I tried this out along our parking pad above. I trimmed back parts of agastache (Anise hyssop), amsonia (Amsonia tabernaemontana), asters (Symphyotrichum novae-angliae), bee balm (Monarda) and black eyed susans that were falling out of the bed to about 6" and left the rest of the plants as is. I also placed the cuttings on the ground in the middle of the planting where you can't see them so seed heads and stems will still be available to insects and birds during winter. Definitely tidier, though not perfect.
Use Short Plants at Edges
This same bed is bordered in the front with amsonia planted as 2" plugs last year. This year, each plant is about 4" wide and a foot tall but already I can see this was a poor choice for the front edge -- too tall. I'm going to move those and replace them with these low, mounding coral bells (Heuchera). Another good choice would be a low growing ground cover such as carex (Carex platyphylla) on the right. It will look neater and help keep taller plants away from the edge.
Add Perennials with Strong Structure
Certain perennials keep their shape for four seasons. These are often described as perennials with structure. Baptisia (Baptisia australis), liatris (Liatris spicata), shorter asters, Indian pink (Spigelia marilandica), and turtlehead (Chelone glabra) all stand tall no matter the season if planted in the optimum light conditions. Adding even a few of these to a planting can give it more order, for lack of a better description.
The Chelsea Chop
If you don't know this term, it comes to us from English gardeners and refers to cutting back late summer flowering perennials by a third or more in late May, the time of the Chelsea Flower Show. The goal is to shorten the ultimate height of late blooming flowers to reduce flopping. I have tried this with asters, cutleaf coneflower (Rudbeckia laciniata), ironweed (Vernonia noveboracensis), joe pye weed (Eutrochium purpureum), and goldenrod (Solidago). Here is a longer list of plants from Longwood Gardens that respond well to this technique. If you have perennials that bloom in August and September, you may want to experiment by cutting them back by at least a third in late May or June to see if you like the results in fall.
A recent National Geographic article on the future of our environment in 2050 predicted natural meadows and woodlands would replace our lawns. Our messy perennial beds could be the gardens of the future. Not there yet? Chelsea chop!