In the Northeast, most of our gardens are designed with a permanent living structure of trees and shrubs, combined with herbaceous perennials that die down to the ground each winter. The garden designer’s job is to combine these plants in a way that works with the environment and is pleasing to the eye. There are hundreds and thousands of perennials to choose from, and many ways to approach the design process. The simplest way is to choose a variety of plants that work well in the given location and flower at different times of the year. Place the tallest plants at the back, and the shortest plants at the front, and you can’t really go wrong -just remember to leave enough room for the plants to grow into their mature size.
I have always found it easiest to start a garden plan with the largest plants and fill in around them. One of my all-time favorite “Back of the Border” plants is Persicaria polymorpha, giant fleece flower. This hardy perennial performs best in moist, fertile soil in sun to part shade. It bursts from the ground in late spring, quickly reaching 4-5′ tall and wide. The massive white, Astilbe-like plumes cover the top of the plant starting in late May. I find that the overall look of the plant is a bit wild, and weedy – but it looks amazing at a distance. The deer may take a nibble, especially early season, but they seem to leave it alone once it reaches its full size. The only drawback in my book is that it does get a bit tired-looking by summer’s end, but don’t we all? Deadheading, and a light pruning after the flowers fade can help a bit.
I was introduced to this plant by a colleague, years ago, and had been hoping to find a spot for it in the garden at the nursery ever since. A few spaces opened up and I got my chance! We planted only three plants in each group at 3′ apart. Now that they are fully mature, I can see that they would have filled the space just as well if planted on a 5′ center.
I think the most successful combination has been with Amsonia ‘String Theory’ and Myrica gale ‘Lowboy’. The Myrica gale serves as a year-round presence at the gate, with its small, grey-green leaves contrasting well with the large leaves of the Persicaria. The airy, fine texture of the Amsonia looks great for the whole growing season, with the added bonus of flowering alongside the Persicaria in early-June.
All in all, I think this plant is a winner! If you have the room, why not give this tough-as-nails perennial a try?