Composer Sandy Wilson must have had late-season daylilies in mind when he penned these lines:
It’s never too late to have a fling
For autumn is just as nice as spring,
And it’s never too late to fall in love.
—The Boy Friend, Act III (1954)
The first late-blooming daylily I fell in love with was red-and-yellow ‘Challenger’, bred in 1949 by pioneer daylily hybridizer A.B. Stout. But the world of daylilies has changed dramatically in recent years—there are now more than 55,000 registered cultivars, all of them bred from just a dozen or so wild species. This mind-boggling statistic demonstrates the gardening public’s admiration for a plant that can be both demure and dramatic, while possessing a cast-iron constitution.
Daylilies (Hemerocallis spp.) are native to China, Korea and Japan, where they grow at the edges of forests and in damp meadowlands. Individual flowers only last one day (hence the common name), but as multiple buds are produced on each flower scape, plants may remain in bloom for weeks at a time. As well, daylilies are among the most disease- and pest-resistant perennials to be found in the herbaceous border.
Writing in Flowers and Their Histories in 1956, plant historian Alice M. Coates declared, “One reason for the deserved popularity of these new daylilies is their hardiness and adaptability; they will grow under almost any conditions, in sand or clay, from Canada to California.”
Daylilies are divided into various groups based on factors such as behaviour of foliage during winter and floral characteristics (see Talking the talk.) They are also classified according to when they flower:
Early (early summer), Middle (midsummer), Late (late summer) and Very Late (early autumn). It’s this last category that in recent years has caused the most excitement. The push is on to develop new cultivars that will bloom right up until the first frosts, an advance that has increased the late-season garden’s colour palette far beyond anyone’s wildest expectations.
Like any plant, newly installed specimens will appreciate extra organic matter, such as compost, leaf mould or well-rotted manure, and sufficient irrigation to establish a strong root system. To reach their full potential, daylilies also require plenty of sunlight; an eastern to southeastern exposure is best, to protect flowers from the scorching rays of the afternoon sun.
Being robust customers, established clumps of daylilies need to be divided after several years’ growth or they will crowd out neighbouring plants. Dig up either the entire root ball, or just a section of it when plants are dormant, and divide the thick, fleshy roots with a sharp spade. Replant divisions at their original depth and water in well.
Diploid vs. tetraploid
Most of the older daylily cultivars are diploids, meaning they have 22 chromosomes. In the early 1960s, plant breeders discovered that treating daylilies with colchicine (a compound extracted from the autumn crocus, Colchicum) could double the number of chromosomes in plants to 44. Daylilies with 44 chromosomes are known as tetraploids; these tend to exhibit more vibrant colours, sturdier petals and sepals, and larger flowers.