Late summer swan song

The late August garden puts on a colourful show with favourite perennials such as black-eyed Susan (Rudbeckia), coneflower (Echinacea), and Russian sage (Perovskia) that provide a long-lasting bloom period.

There is also monkshood (Aconitum), with its satiny, purple-hooded flowers and meadow rue (Thalictrum), with airy clouds of tiny, lavender flowers.

The velvety buds of grapeleaf anemone (Anemone tomentosa Robustissima) are just beginning to open now for a mass display of pink-petalled flowers with showy yellow centres.

There is also James Compton bugbane (Actaea simplex) with its creamy white bottlebrush-like flower spikes that wave in the late summer breezes.

This rich plant tapestry is a valuable source of nectar for bees, butterflies and hummingbirds.

And yet, a common refrain (read lament) heard from gardeners at this time of year is that the garden looks tired. It’s understandable, after a season of eccentric weather.

Let inspiration take root and deliver fresh, even surprising, colour that will extend your garden into autumn. It might mean removing an underperforming plant to make more room.

But this is a perfect time for planting, as the warm soil will encourage rapid establishment of root systems. Cooler temperatures allow new plants to adapt readily without heat and water stress.

Asters provide a beautiful finale to the perennial garden. There are several New England asters (Aster novae-angliae) that bloom from August to October. Varieties that are hardy to Zone 3 include Grape Crush, Pink Crush, Purple Beauty, Purple Dome, and Rose Beauty. With compact habits ranging from 60 to 100 cm tall, New England asters are best suited to sunny, well-drained borders.

A dramatic option is the flat-topped white aster (Doellingeria umbellatus) which is native to Manitoba. Masses of white daisy-like flower clusters with a yellow centre disk sit atop tall stems with long, tapered green leaves. It grows 90 to 120 cm tall, but this stately perennial looks even taller in Tim Evans’ St. James garden, where he has planted it in groups in a broad circle around a white statue.

Evans purchased his white aster from Prairie Originals, a native plant nursery in St. Clements.

“I usually chop it down so that it’s nice and level,” Evans says. “When you chop it down, it increases in buds and blooms about a week later. But this year, I thought, I’m not going to bother.”

The display looks spectacular — an airy cloud of white flowers that blooms in August and September and provides lots of nectar for bees. Flat-topped white aster is also a host for Harris Checkerspot butterfly caterpillars.

There are so many different types of stonecrop (Sedum) that one could almost colour their fall garden exclusively with this durable, fall-flowering succulent. Choices range from upright varieties to low-growing or creeping ground covers.

But a perennial favourite year after year for both gardeners and pollinators has been Sedum spectabile Autumn Joy stonecrop. Autumn Joy’s large clusters of dusty rose-coloured flowers on 50 cm tall stems come into their glory in September and bloom into October.

Several new challengers have emerged to test the reign of this fall classic. Top contenders include Rock’N Grow stonecrop series which counts five different varieties, Midnight Velvet, Lemonjade, Coral Jade, Back in Black, and Tiramisu. Slightly more compact than Autumn Joy, the Rock’N Grow series offers a range of colours and heights from 41 to 61 cm.

New Cloudburst Burgundy Stonecrop and Cloudburst Green Flash Stonecrop are compact sedums with a height and spread of just 35 cm. Cloudburst Burgundy has dark burgundy blooms above nearly black succulent foliage. The series has been bred for powdery mildew resistance. New colours will be added to the collection for 2027.

Still, it’s hard to beat Autumn Joy sedum, says Shea Doherty of Our Farm Greenhouses in Portage la Prairie. “Autumn Joy is one that doesn’t mind an early cool spr ing. It’s still my top variety.”

Sedum spectabile Spectacular is an intriguing seed-grown stonecrop introduced by PanAmerican Seed. New for 2027, Sedum Spectacular is a compact variety (30 to 35 cm tall) with bright chartreuse-green rounded foliage and medium-sized light pink late-summer flower clusters.

The shorter, stronger stems have been developed to not easily break or flop open, award-winning variety 30 to 35 cm. In my garden, Spectacular’s chartreuse foliage provides a high-contrast punch against standard green-leaved plants.

By fall, the faded leaves of hosta plants rarely look energetic. But Mukdenia rossii Karasuba, more widely known as Crimson Fans, is just beginning to come into its own. A member of the Saxifragaceae family, don’t assume that this part-shade perennial is not hardy just because it is so underused in Zone 3 gardens.

A compact, mounding perennial with deeply lobed, maple-like leaves, Mukdenia will literally grow on you. Its tidy habit in early years gradually expands up to 60 cm across. In deep shade, the leaves remain green but in a part sun location, the foliage develops fabulous red tints that transition to a striking, orange-tinted red.

I only grow two Mukdenia plants in a mostly neglected area of my garden, but they return faithfully each spring and produce lovely white, short-stemmed flowers. Give this one a try!

I can’t say enough about Chelone Tiny Tortuga turtlehead as an ideal perennial for autumn. This dwarf turtlehead variety grows to 30 to 40 cm tall. Amazingly adaptable to full sun or part shade locations, Tiny Tortuga spreads slowly by underground rhizomes to form a low hedge with dark green foliage.

By late August or the first week of September, short spikes of deep pink, two-lipped, snapdragon-like flowers burst into bloom. The flower show lasts all of September and into early October and attracts bees, butterflies and hummingbirds. I wouldn’t be without this perennial. (Bonus: Tiny Tortuga is not bothered in the least by powdery mildew or insect pests.)

In the market for an ornamental grass other than the ubiquitous Karl Foerster feather reed grass? Check out Chameleon Little Bluestem (Schizachyrium scoparium). This attractive clump-forming grass has a mature height of just 60 cm. The upright, narrow leaves are a kaleidoscope of soft colour — striped green and cream before developing pink to light purple tips as temperatures cool.

Hydrangea shrubs are garden stalwarts with their long-lasting summer-to-fall blooms that this year seem bigger than ever thanks to June’s abundant moisture. I’ve never met a Hydrangea paniculata that I didn’t love but Hydrangea Spring Sizzle — named for its early flowering — makes a gorgeous statement in late summer with white blooms that transition to vibrant, rosy-pink. Seeing is believing.

For scintillating colour in October, you can’t go wrong with Virginia creeper (Parthenocissus quinquefolia). This vigorous climbing vine with its brilliant red, five-leaved foliage is adaptable to full shade although the best fall colour is achieved in a full sun location. It climbs with tendrils and will quickly cover fences, pergolas or arbors.

Virginia creeper is an important food source for birds which love the small dark berries that grow in clusters on bright red stems.

Local garden centres will have even more inspiration in store for your fall garden.

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