Perennial favourites

It’s perennials season, not only in our gardens but at local garden centres, where fresh shipments are arriving weekly.

While annuals bring vivid colour to containers and brighten borders, perennials are garden essentials.

Each year, Craig Gillespie, horticulture supervisor of the outdoor gardens at Assiniboine Park Conservancy, orders 300 to 400 perennials to add to the English Garden.

“I’m always looking for something different,” he says.

This year he was thrilled to find Dictamnus albus, commonly known as the gas plant. “I purchased both the pink and white varieties.”

Gillespie is still searching for great burnet (Sanguisorba officinalis), which has deep red bottle-brush flowers, and Knautia macedonica (Macedonian scabious), which has deep crimson pincushion-like flowers.

The thrill of the hunt in finding plant varieties we long for is familiar to all gardeners. Need some inspiration for choosing beautiful perennials that are dependable performers? I asked Gillespie to share the names of some of his favourites.

“Callie’s Memory peony is fantastic,” says Gillespie. “It’s just a gorgeous peony.”

Prized for its unique colour combinations, this impossibly beautiful Itoh peony blooms with peach, pink and yellow flowers with variable dark pink striping. Itoh peonies, also known as intersectional peonies, are a cross between a tree peony and an herbaceous peony. They combine the best characteristics of both and typically do not require any staking.

Callie’s Memory was introduced in 1999 by Roger F. Anderson, a renowned peony hybridizer, and was named for his beloved dog. Callie’s Memory has large semi-double to double flowers.

Callie’s Memory peonies are planted together in a large grouping in one area of the English Garden. They were in full bloom last week. You may still be able to catch the finale of their spectacular show.

Back row standouts

Backdrops, of course, set the stage in any garden design to enhance the visual impact of flowering displays. Behind the sweep of Callie’s Memory peonies in the English Garden stands the mighty giant fleece flower (Persicaria polymorpha) which is currently in full, majestic bloom. Featuring large plumes of creamy white flowers and dark green, lance-shaped leaves, giant fleece can grow to 1.8 metres or more, which is contrary to the smaller size (90 to 120 cm) suggested by some nursery catalogues or plant tags.

“I am over 1.8 m. tall and the giant fleece flower plants in the English Garden tower over me,” says Gillespie. “If you have space, it is definitely a plant to have.”

Placement is an important consideration, he says.

“Giant fleece flower performs best in full sun but is tolerant of dappled light. The heavier the shade, the weaker the growth will be.”

Hardy to Zone 3, giant fleece flower blooms for several weeks. It is tolerant of wet sites.

Gillespie is fond of daylilies for their easy care and colourful flowers. He likes to plant a single cultivar in masses of 25 for impact.

“For the home gardener, planting a single specimen or in groups of three can provide impact, but the English Garden is so big that a lone specimen does not work unless it is a tree or something huge.”

This year, Gillespie has added a mass planting of Hemerocallis Pansy Face Charmer in the English Garden. A reblooming daylily, Pansy Face Charmer has flowers that can reach 14 cm across. The bright yellow green throat pattern with a dark maroon ruffled edge is reminiscent of a giant pansy, says Gillespie. He started Pansy Face Charmer daylilies as bare root perennials in the greenhouse at Assiniboine Park.

One of Gillespie’s favourite perennials is Phlox paniculata, which will begin blooming around mid-July.

“Last year we planted Phlox paniculata Jeana, a tall (60 to 120 cm) garden phlox which was the 2024 Perennial Plant of the Year. It did very well as a first-year plant and this year the plants have come back nice and bushy, so it should provide a much stronger show. But that said, phlox probably must be one of the absolute favourites of deer, which nip off the buds at the first opportunity.”

Fencing protects some areas of the English Garden from deer browsing, says Gillespie, and so far, there has been minimal deer activity. Gillespie would prefer to not use an organic deer repellent because of its strong odor. “Phlox has a sweet fragrance and you kind of lose that if you spray the plants.”

Jeana phlox has tiered layers of lavender pink blooms on sturdy stems. In extensive plant trials, Jeana demonstrated exceptional powdery mildew resistance. This unique variety offers an impressive floral display that extends from mid-July to early September.

A fine pair

Astrantia major, commonly known as great masterwort, draws high praise from Gillespie. A garden ornamental that has umbel-like clusters of tiny flowers on wiry leafless stems above a thick basal skirt of deeply lobed palmate leaves with toothed edges, astrantia is an upright clump-forming perennial with a moderate height of 60 cm. It spreads slowly by underground stolons and will self-seed in optimum conditions. If this is not desired, remove the flowers after blooming.

“Astrantia works well in sunny locations, dappled shade or full shade,” says Gillespie.

A member of the carrot family, astrantia is a trouble-free perennial which blooms for several weeks starting in early summer. In the English Garden, astrantia has been paired with astilbe beneath a rosy bloom crabapple where it receives dappled light.

Astilbe has a greater presence in the English Garden today than has been seen in past years, says Gillespie.

“Astilbe looks fabulous in a mass planting. We planted numerous astilbes last year in the English Garden. Now that there are varieties with dark burgundy foliage — Dark Side of the Moon, for example — it’s possible to create a different look.”

Varieties to look for include Colour Flash Astilbe, which boasts colour-changing foliage that starts out bright green in spring, maturing to a rich green with hues of burgundy and purple in summer and red in fall. Chocolate Shogun Astilbe has chocolate bronze foliage and pale pink flower plumes.

“Even when astilbe is not in bloom, the fern like foliage provides great texture,” says Gillespie.

What makes astrantia and astilbe such a workable combination in the garden? Both share similar traits such as deeply cut, toothed leaves and a preference for moist soil. The frothy, colourful plumes of astilbe provide a striking contrast to the domed umbels of astrantia.

“We are constantly adding more and more perennials to the English Garden and not relying on quite so many annual flowers,” says Gillespie. “I know that perennials seem expensive at first, but they do pay for themselves in the long run, especially perennials that can be divided once they mature.”

For inspiration, plan to experience the ever-evolving perennial display at the English Garden in Assiniboine Park throughout the growing season.

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