Using shrubs is one way to take up room in a garden, but it is also possible to have tall perennials serve the same function. I have several tall perennials in my garden that I realize are not well placed, partly because they are overcrowding each other. I will be reorganizing them in the fall. In the meantime I want to suggest some tall, dare I say statuesque, perennials that can make quite a statement in a flower border.
Right now Filipendula rubra, queen of the prairie, is producing delicate pink astilbe-like flowers on which can reach six to eight feet. The deeply cut bright green leaves are as fragrant as the flowers. It is easy to grow and tolerant of wet sites and clay soil. Even though it can become very tall it does not need staking making it ideal for back of the garden border. It likes the sun, but can tolerate some shade. Tall plants like this make a really dramatic clump.
If you have a shady spot Actaea racemosa, formerly known as Cimicifuga, and always also known as black cohosh, can reach a height of six feet. If the site is particularly fertile and damp, the one to two foot white spires rising from the dark foliage can reach a height of eight feet. Depending on the site and weather, it can begin blooming in July, August or September. It stays in bloom for at least three weeks. This stunning plant also serves as a host plant and nectar source for the Spring Azure butterfly (Celastrina ladon). I had this growing in my Heath garden and it was a real attention grabber glowing as it did in the shade of an ancient apple tree. Cimicifuga seems to enjoy the sun just as much blooming as it does on the Bridge of Flowers.
Another tall native plant is Culver’s root, Veronicastrum virginicum which will reach a height of seven feet including the nine inch spikes of small white flowers. It needs damp to wet soil and will bloom in July and August. To extend the bloom season, cut back the spent flower. You can even cut it back to the basal leaves and possibly get a second flush. Like the queen of the prairie, Culver’s root, is a good choice for a rain garden. It also attracts butterflies.
Joe Pye weed, Eutrochium purpureum, is known to many people as a roadside weed, but there are different species in the Eutrochium genus. That explains why one Joe Pye weed in my garden looks nothing like the roadside variety, and the second Joe Pye weed looks nothing like either one because it has variegated foliage. What they all have in common is their size, up to six or seven feet, and mauve dome-like flowers that appeal to many butterflies and bees. There is a dwarf Baby Joe that will not grow taller than three feet and has blooms in a deeper shade of purple. Joe Pye weed is another plant that will thrive in a rain garden.
Boltonia is another wonderful plant that can reach a height of six feet and will need little or no staking. Having said that I have to say that the boltonia on the Bridge of Flowers is very happy to be able to lean on the wire fence behind it. From August through September Boltonia is covered with tiny white daisy like flowers. Once in a while those white petals will have a pink or mauve tint. For a slightly more sturdy and compact plant Boltonia asteroides var. latisquama‘Snowbank’ (3-4’ tall) might be a good choice if you are not necessarily looking for a statuesque beauty, but are looking for lush autumnal blom.
I have two very tall perennials in my garden. Right now my giant meadow rue (Thalictrum rochebrunianum) with its cloud of tiny lavender blossoms is about eight feet tall. This is an unusual height; six feet is more common. It is a hardier plant than you might imagine looking at the delicacy of its flowers and its foliage which looks very similar to the foliage of the spring columbine. I planted it a couple of feet into the garden bed, but this spring the few stems I had last year sent out about a million babies. I pulled out a lot of those babies, but it was hard to get rid of them all, even when I tried. Right now the meadow rue and the variegated Joe Pye weed look like passionate kissin’ cousins right at the edge of the bed. They will bloom into September.
The other equally tall perennial is Hemerocallis ‘Altissima.’ It has not yet reached its full height, but this daylily will be at least six feet tall. Like all daylilies, it has increased each year and in the fall I will have to divide it.
I have certainly not named every tall perennial available for the backyard garden. I visited a friend some years ago who used perennial sunflowers (Helianthus) to create a hedge on one side of his corner garden. Another friend lined a walkway with a profusion of lacy white fleece flowers (Persicaria polymorpha) reaching six feet tall. Delphiniums can be tall, from four to six feet, but there are smaller varieties as well. They come in a range of blues, and white as well.
A striking tall annual flower is the deep red Love-lies-bleeding, Amaranth, that can reach five feet and is useful in fresh or dried flower arrangements.
Tall or small, there is always great variety for the flower garden.
Between the Rows July 21, 2018
I really like this post–for many reasons, but especially because you showed and described Black Cohosh and Culver’s Root in the same post. Many people seem to get them mixed up. I have two large patches of Black Cohosh (we also call it Bugbane) in my garden, and the pollinators love it! Culver’s Root is awesome, too, as are the other plants you mention. It is great to have a few very tall perennials to add visual interest and structure to the back of a garden bed.
Beth – thank you for filling in about the ways plant names can be confused. I was in a friend’s garden yesterday admiring what I thought was a culver’s root, or a regular veronica, but she said neither. Now I am searching for this plant which does have a very interesting foliage structure. Keep watching.