The joy of late-season colour
Some perennials can be persuaded to bloom again
With these lazy summer days beginning to turn crisp at sundown, we might think that the time for flowers in our gardens is coming to an end. It’s true that the fresh growth and reliable blooms of June’s flowers are long gone, but you’ll be happy to know that the tail end of summer can provide us with just as much colour if we plan and put in a little work.
The trick to late summer and early fall flowering is threefold:
1Choose plants that, with a little help from you, will be encouraged into a second flush of growth and hopefully another bloom cycle.
There are a number of perennials that can be persuaded to bloom again later in the season if they are sheared back. For example, plants like spiderwort (Tradescantia), cranesbill (Geranium), catmint (Nepeta), lungwort (Pulmonaria) can all be sheared back quite severely (to four to six inches) and if they are fed, watered regularly and we have a generous autumn, they will not only re-sprout with fresh foliage but also likely bloom again. This type of shearing is best done in midsummer (early to mid-July) and not done at all if the plants are stressed as it may end up having the opposite effect and kill them. (By the way, when I say ‘feed,’ rather than using a synthetic fertilizer, I mean top-dress or generously sprinkle with compost, water with compost ‘tea’ (suspend a giant tea bag of manure, using cheesecloth, in your rain barrel) or use a natural fish or seaweed-based fertilizer.)
Other perennials don’t necessarily take kindly to shearing but rather respond to deadheading (cutting off their spent blossoms individually). This can be more of an arduous task and it pays to know which perennials to concentrate on before you commit to this kind of love and attention: shasta daisy (although if you just want fresh basal foliage, go ahead and shear), black-eyed Susan, coneflower, clary or meadow sage, veronica, fever-few, bellflower, bee balm, border phlox, delphinium, lance-leaf coreopsis and blanket flower are some that will react to having their flowers removed by producing more later on. If you have the time and inclination, you can deadhead stem by stem or, if you’re impatient, take the shears to each clump and slice off the spent tops in one motion.
There are some other plant varieties that will produce a second bloom later in the season without you doing a thing. Look for reblooming varieties of day lily, of which there are many besides the ubiquitous ‘Stella d’Oro’ (for example, Hemerocallis ‘Happy Returns’ and ‘Rosy Returns’) and bearded iris (for example, Iris x germanica ‘Again and Again’, or look for those with ‘Autumn’ in their name, signifying late-season rebloom), as well as lilac (Syringa x ‘Boomerang’) and the ‘Sonic Bloom’ series of weigela.
2Consider perennial plants that will bloom freely for a long period of time, well into the fall, with no real help from you.
There are some plants that just bloom their hearts out almost all season long and they belong in almost every garden. Some of these true workhorses are: yellow fumitory (Corydalis lutea) and fern-leaf bleeding heart (Dicentra formosa) for shaded gardens and thread-leaf coreopsis (Coreopsis verticillata, especially ‘Moonbeam’), ‘Rozanne’ cranesbill (Geranium x ‘Rozanne’), Russian sage (Perovskia atriplicifolia), gaura (Gaura lindheimeri) and yarrow (Achillea millefolium) for full sun.
Others are long late-season bloomers, like snakeroot (Cimicifuga/Actaea) and Japanese anemone (Anemone japonica i.e. ‘September Charm’; careful, this one can be a runner) for areas in part sun, and then border sedum (Sedum spectabile), asters (i.e. Aster x frikartii ‘Monch’), Joe-Pye weed (Eupatorium) and the elegant but understated meadow rue (Thalictrum rochebruneanum) for beds getting sun for most of the day.
3Incorporate annuals into your garden beds for late-season colour.
In truth, the most colourful gardens in the late summer are those with annual plants because they are in their flowering glory at this time. I am not suggesting you plunk down annuals in your perennial beds without giving some thought first to how they will relate to what you already have there. There are several annuals that have the appearance of perennials and these are the ones that will blend in seamlessly. Try the taller flossflowers (Ageratum houstonianum ‘Blue Horizon’), celosia (especially ‘Cramer’s Amazon’), godetia (or clarkia), coleus, coreopsis (especially C. tinctoria ‘Mahogany’), cosmos, dill, marigold (especially M. ‘Villandry’), hummingbird sage (Salvia subrotunda) or Salvia patens, zinnia (especially Z. peruviana ‘Red’) and others.
The one caveat: It’s likely you’ll have to grow these annuals from seed yourself, since many nurseries still haven’t moved beyond the standard fare.