Saskatchewan Perennial Society
Chrysanthemums (Chrysanthemum x morifolium) (also known simply as ‘mums’) bring colour to the autumn border, are great cut flowers and are attractive to butterflies. But they require special attention to overwinter and are not easy perennials to grow in prairie gardens. Cultivated in China for over 2,500 years, they were brought to North America in 1798. The genus name is from the Greek words chrysan and themum, meaning golden flower.
They have a short, fibrous root system which forms a dense, woody crown from which emerge many stems. Flowers may be single and daisy-like but are more commonly double. Varieties developed for northern gardens begin to flower in August, triggered by shortening days
Plant them in full sun in well-drained but evenly moist soil rich in organic matter. A summer mulch helps to maintain even moisture and suppress weeds. Use a balanced fertilizer such as 20-20-20 or organic fertilizers such as alfalfa pellets, blood meal or bone meal to promote vigorous growth. Pinch the plants in early summer to encourage branching and more abundant flowering.
After the first severe killing frost in fall, cover them with 15 to 20 cm (6-8 in.) of organic mulch such as shredded leaves or clean straw to prevent soil heaving and drying due to freeze-thaw cycles and to protect the crowns from winter’s cold. Remove the heavy mulch as soon as spring temperatures rise above freezing and snow recedes. Divide every second year to keep the crowns vigorous and improve their chances of winter survival. Plants can be divided as soon as the soil warms in the spring or from cuttings taken in early spring.
The Chrysanthemum Conundrum
Experienced prairie gardeners report very limited success in overwintering mums in the garden as they seldom survive without significant interventions in zone 2 and 3. It might be easier to simply treat them as annuals.
Hugh Skinner grew and propagated the Morden series of mums for years in his nursery near Roblin, Manitoba. He started plants in the greenhouse in late winter from stock plants overwintered for one year in the garden. These plants had been grown with excellent drainage and shelterbelt protection. With the exception of ‘Morden Garnet,’ which died, the Morden mums generally survived only their first winter outdoors. The following fall, the large clumps would be dug, potted, and stored in a root cellar until brought into growth in the greenhouse to produce cuttings in late winter.
Plants left in the garden generally did not survive a second winter. The “secret,” beyond planting them in a protected, well-drained site, was to divide or start new plants every second year. The experience of a veteran gardener in Saskatoon has paralleled that of Hugh in Manitoba.
‘Baby Tears’ – compact plant (30 cm / 12 in. x 40 cm / 15 in.), white pompom flowers tinged pink.
‘Holly’ – golden yellow, pompom flowers on compact plants (40 cm / 15 in.).
‘Prairie Lavender’ – shell pink with yellow centres (60 cm / 24 in.).
• The Firecracker series, from Jeffries Nurseries, breed by Rick Durand, are about 50 cm (20 in.) in height.
‘Dream Weaver’ – soft mauve-pink
‘Firestorm’ – mauve-pink to scarlet-red with yellow centres
‘Power Surge’ – double red
‘Showbiz’ – pink-mauve, pompom
‘Stardust’ – dusty mauve, quill-like petals with yellow centers
‘Suncatcher’ – bright yellow, double
‘Tiger Tail’ – bright orange-yellow
• The Morden Series, Agriculture Canada Morden Research Station, 1960s -1970s are 40 to 50 cm (15-18 in.) in height and spread.
‘Morden Cameo’ – double, creamy white (40 cm / 15 in.).
‘Morden Canary’ – bright yellow (45 cm / 18 in.).
‘Morden Delight’ – double, bronze-red (45 cm / 18 in.).
‘Morden Fiesta’- bright purple, compact (40 cm / 15 in.).
‘Morden Gaiety’ – bright orange (40 cm / 15 in.).
Korean chrysanthemums (C. x rubellum hybrids) are reliable and generally easier to grow in northern gardens than those described above. The single flowers surround yellow disc florets.
‘Clara Curtis’ – deep pink, single flowers with yellow centres (60 to 75 cm / 24-30 in.), has survived for many years in Hugh’s Manitoba garden and in Saskatoon gardens with minimal attention.
‘Mary Stoker’ is of similar stature with yellow flowers overlaid with light pink.
C. weyrichii, an alpine species native to Japan and Sakhalin Island, has large, single, white or pink flowers (25 to 40 cm / 10-15 in.). The most available variety, ‘White Bomb’, is being used by Canadian breeders to develop hardy mums in a variety of colours and forms.
Sara Williams is the author and coauthor of many books including Creating the Prairie Xeriscape, Gardening Naturally with Hugh Skinner and, with Bob Bors, the recently published Growing Fruit in Northern Gardens. She continues to give workshops on a wide range of gardening topics throughout the prairies. This column is provided courtesy of the Saskatchewan Perennial Society (SPS; firstname.lastname@example.org ). Check our website (www.saskperennial.ca) or Facebook page (www.facebook.com/saskperennial) for a list of upcoming gardening events