Late Blooming Perennials 1 - Edmonton Horticultural Society

by Maggie Easton
Photos below by Maggie Easton (taken in her garden)

Many of us have early blooming perennials in our gardens. Most of us visit the greenhouses and nurseries in spring and are attracted by the lovely blooms of the spring and early summer perennials. However, by mid-August our perennial borders may be looking a bit tired.  Most of the late blooming perennials don’t look great in pots. Many are also sold in larger pots so that their cost becomes a factor. Don’t be discouraged by all this. It is possible to keep our gardens looking their best with some fabulous perennials in bloom from mid-August right up until the first hard frost. Let’s look at some of these plants in more detail.

Joe Pye Weed

Joe Pye Weeding - Edmonton Horticultural SocietyThe first one I want to mention, and one of my personal favourites, is Eupatorium maculatum, also known as Joe Pye weed. It is a North American native, which may be why this gorgeous plant has been labelled a ‘weed’.  Joe Pye is a large plant; it grows up to 7 ft. tall and 3 ft. across.  Grow it in a sunny spot, or part shade if that is the best you can do.  It likes consistently moist soil. The flowers are borne in large panicles of light to deep purple.  Bees and butterflies (and other pollinators) are attracted to this plant. It is stunning when in full bloom and the flowers last a long time. Grow this beauty at the back of the border, with shorter plants in front. It is not the greatest looking before it blooms and the flowers are at the top of stems, so tall enough to tower over almost everything else.

Coneflower - Edmonton Horticultural SocietyConeflower

The second perennial I like that blooms late in the season is Echinacea purpurea. This plant is commonly known as coneflower, because the flowers are daisy-like, with sharply reflexed petals and a conical centre. The species has pink flowers, but cultivars are available in white, orange and yellow. Deadhead for more abundant blooms. Coneflower can grow up to 5 ft. tall if it is happy, but usually it stays a more manageable 3-4 ft.  Grow it in full sun and avoid areas where water pools in spring or during rainstorms as it dislikes wet feet. The pink or white cultivars are great companions for Joe Pye, since the colours blend well and the flower shapes are a nice contrast.

Blanket Flower - Edmonton Horticultural SocietyBlanket Flower

On a smaller scale, and with a very long bloom time, is Gaillardia grandiflora, or blanket flower.  It is native to the prairies and thus does very well here. It starts to bloom in mid-July, and like the Energizer bunny, keeps going and going and going, right to frost. There is no need to deadhead, since the seed heads are attractive and you want a bit of self-seeding.  Blanket flower is short-lived, so it helps to have seedlings coming along. I haven’t noticed that self-seeding is a problem in that I only seem to get enough seedlings to keep the show going from year to year. The flowers are daisy-like, with yellow ray flowers that are red at the base. They vary in height depending on the cultivar, anywhere from 1-3 ft. tall.  They make excellent cut flowers.

Garden Phlox - Edmonton Horticultural SocietyGarden Phlox

Another showy perennial for the back of the border in late summer is Phlox paniculata, or garden phlox. Phlox enjoys a sunny spot in moist, well-drained soil. It grows up to 4 ft. tall, and as wide. This plant benefits from dead heading to prolong flowering. The flowers are borne is large corymbs (clusters) and come in white, pink, violet and red.


Heather - Edmonton Horticultural SocietyHeather

A plant that many people think can’t be grown here is heather, Calluna vulgaris to be precise.  Technically, it is a low growing shrub but I think of it as more of a perennial. In our climate, it rarely gets taller than about 8 ins, and you may want to plant several close together to get a good show. There are many varieties available, and some do not bloom until September or October, which is a little late for us. Look for varieties that bloom July and August. The flowers are bell shaped, very small, but numerous. They come in shades of white, pink and red. The foliage often has bright red or yellow on the new growth in spring. Plant them in sun where there is reliable snow cover in winter. An excellent source of these delightful plants is the Heather Farm, a mail-order vendor in BC.  Their website is

False Sunflower - Edmonton Horticultural SocietyFalse Sunflower

Who doesn’t love sunflowers?  There are perennial sunflowers as well as the annual ones with the huge flowers and seeds that are attractive to birds and people alike. The perennial, often called false sunflower is Heliopsis helianthoides. This is another sun lover for the back of the border. It grows to 6 ft. tall and about 2 ft. across.  It bears numerous yellow daisy-like flowers that are about 2 ins. across. The ray petals are yellow, and the disc flowers are brown. They make excellent cut flowers.  Be warned, however, H. helianthoides self-seeds prolifically.  The seedlings aren’t hard to pull out once they reach about 3 ins. in height and they can be numerous.

Turtlehead - Edmonton Horticultural SocietyTurtlehead 

Chelone glabra, or turtlehead, is a perennial that blooms late summer to early fall with weather-resistant flowers. It tolerates more shade than many late bloomers. The flowers are two-lipped with a beard. They come in shades of pink or white. Turtlehead can get up to 3 ft. tall, but 2 ft. is more common.


Pearly Everlasting - Edmonton Horticultural SocietyPearly Everlasting

A late bloomer for the middle or front of the border is Anaphalis margaritacea, or pearly everlasting. This plant carries small corymbs of flowers. Individual flowers are tiny, yellow and surrounded by white bracts. The bracts are what is most noticeable — you have to really look for the tiny yellow flowers. The bracts last a long time, hence the common name of pearly everlasting. This plant gets to be about 2 ft. tall and wide. It makes good cut flowers and is easy to divide if you want more clumps.

Goldenrod - Edmonton Horticultural SocietyGoldenrod

Goldenrod has a bad rap. It is blamed for causing hayfever and is also said to be invasive.  Actually, goldenrod (Solidago) is not what causes hayfever. Ragweed is the culprit and it blooms at the same time as goldenrod. The pollen from goldenrod is too heavy to waft about on the air and be breathed in by allergy sufferers.  As for its invasive tendencies, there is some truth in that. Some species are very invasive, but there are also many clump-formers, which are well-behaved in the garden. Some of the newer hybrids have larger, longer-lasting flowers than the species and deserve a place in the perennial border. Goldenrod has yellow flowers borne in one-sided spikes on stiff stems. Look for named cultivars and check the label for growth habit to ensure your plant won’t turn into garden thugs.

There are many other perennials, and a few shrubs that bloom in late summer or fall.  Among these are Ligularia dentata for shade, Rudbeckia, late-blooming Hemerocallis (daylilies), repeat-blooming roses, Anemone tomentosa (Japanese anemone) and various cultivars of Hydrangea paniculata, better known as PeeGee hydrangea or Pinky Winky hydrangea.  Various grasses also provide interest and colour in fall and well into winter.