The lone voice of horticultural reason

August Blooming Perennials

Come the latter part of August, the mood created by my flower garden always reminds me of the atmosphere at a wedding reception after the bride and groom have left; there’s still bits of frivolity here and there, but it’s clear the main focus of the celebration is missing.

What many gardens have been lacking the past few weeks is fresh, new color. Deadheading-my topic a few weeks ago-certainly helps at this time, as does the use of annuals, but it’s hard to beat the sudden, surprising arrival of a brand-new clump of bloom to the party.

The problem is that over eighty-percent of the perennials we can grow in Minnesota have bloomed and faded by the second half of August, so until the mums, boltonia, fall asters, solidago and sedums fill my beds with fresh new blooms in the next few weeks, I must admit the current stretch in the growing season has my humble half-acre looking a bit dowdy.
Let this be the last year. I resolve to spend a little extra effort next spring procuring and planting some August-blooming specimens, to be certain this is the last time I encounter this problem. For advice, I rang up Mike Heger, proprietor of Ambergate Gardens in Victoria, one of my favorite spots to shop for top-quality, homegrown, distinctive perennials. Here are a few of Mike’s recommendations for mid- to late-August bloomers:

  • Veronicastrum (Culver’s Root)-Not only a late summer bloomer, but tall, dark green and handsome, too. Spires of white or pale lavender flowers atop stems upwards to 6′. Gives a proud, bold, vertical accent to the back of the border right when you need it most. Full sun.
  • Boltonia “Pink Beauty”-Blooms a good three weeks ahead of “Snowbank,” the boltonia I grow; will do fine in part sun but performs better in full. Creates clouds of small, pink, daisy-like flowers atop stout, 4′ stems. Nearly impossible to kill, boltonia is one of my favorite perennials.
  • Perovskia (Russian Sage)-I should have thought of this one. In fact, I grew it a long time ago, before I raised the beds out by the street, back when everything I grew down there flooded out and rotted by the fourth of July. Fine spikes of lavender-blue flowers set off from silvery leaves make it a real showstopper when massed. Can it sneak by with a little less than full sun? We’ll find out.
  • Cassia (Wild Senna)-Here’s one the neighbors don’t have. Will grow 3′ to 6′ with a shrub-like appearance, then produce clusters of lively yellow, pea like flowers near the tops of the stems. Full sun.
  • Patrinia (Patrinia)-A tall yellow for you that blooms from August into September. Presents tiny flowers in profuse clusters and performs well in part sun. It doesn’t like to be disturbed, so plant it where you want it the first time.

Well, there’s the start of my list for next spring. Kick out the ones that require full sun-there are stretches of my yard that haven’t seen full sun since the ’20s-and I still have three to try.

To this list I’ll add a few of the newer, late-blooming varieties of Hemerocallis (daylily). “Chicago Apache” is a tall, ruffled red, “Golden Prize” is a medium, solid gold, and “Green Flutter” is a short show-stopper featuring a canary yellow bloom with green throat. All start blooming in late July and after just a few years of growth should keep your garden party in full swing straight through to September.

Don Engebretson
The Renegade Gardener