Hardy chrysanthemums create welcome shades of warmth and brightness
As the days shorten and the first frosts bite, a kaleidoscope of vibrant hues still shimmer in the autumn light. Blooming prolifically long after
other perennials have faded, the flowers of hardy chrysanthemums continue to inject welcome colour into late borders. In lustrous shades of gold, bronze, pink, red, purple, salmon, white and cream, they brighten the dullest day.
With a variety of flower forms, heights and habits, there is one for every sunny spot in the garden. Compact forms are ideal for containers while taller ones thrive in beds and borders. Different varieties flower in early, mid or late autumn, extending the season as late in the year as possible. One variety, chrysanthemum ‘Christmas’, lives up to its name most years.
These useful, colourful and versatile plants are slowly reclaiming their place in British gardens. In the mid 20th century they were one of the most popular flowers but eventually fell out of favour. They suffered from misconceptions that they were tender, and took a lot of care.
Their resurgence is largely thanks to the work of growers such as Dr Andrew Ward and Judy Barker. They are the joint holders of two dispersed National Collections.
“Hardy chrysanthemums are often confused with tender exhibition varieties grown to win prizes for their size and perfection,” says Andrew. Another confusion is with commercially grown cut flowers and the ubiquitous ‘pot mum’. This floriferous, potted variety is treated with a dwarfing hormone to keep it compact. “Both exhibition and florists’ chrysanthemums are frost tender, whereas hardy varieties survive very low temperatures. Ours survived temperatures of -18°C during the winter of 2010,” he says.
“An ideal soil is reasonably well drained, but they thrive on clay that has been improved with sharp sand. Many growing here have stood in water for weeks in bad winters, and survived.”
Originally, he too made the mistake of dismissing all chrysanthemums as tender and demanding. Then 27 years ago, he bought C. ‘Innocence’, a purchase inspired by its colour and the simplicity of the name. “I was amazed by its late flowers, ease of growth and hardiness,” he recalls. Following this discovery, he bought as many new varieties as possible, establishing Norwell Nurseries, Nottinghamshire. Today this houses one of Europe’s largest collections of hardy chrysanthemums with more than 100 cultivars. “I believe that propagating and dispersing our plants as widely as possible is the best way to preserve the many fabulous old varieties that might otherwise be lost,” he says.
The chrysanthemum family comprises a handful of species of herbaceous perennials. Over the centuries, cross-breeding has given rise to scores of hybrids with showy, daisy-like flowers. Both plants and flowers vary greatly in size. They range from Asian miniatures that fit into bonsai bowls to football-sized, Japanese exhibition hybrids.
Chrysanthemums come in different flower forms such as singles, doubles, semi-doubles and pompons. Each flower is made up of petals, or ray florets, that attract pollinating insects to a central disc comprising scores of miniscule disc florets. Each disc floret is, in fact, an individual flower in its own right. It comes complete with anthers to produce pollen, a stigma to receive pollen, and the ability to produce seeds. The dark green, lance-shaped leaves vary between 1¾in (4cm) and 7in (18cm) in length. Aromatic when crushed in the fingers, they are either shallowly or deeply lobed and often feathery in texture. C. ‘Burnt Orange’ has fern-like foliage, while the leaves of ‘Emperor of China’ turn beetroot red in late autumn.
Heights range from 15in (38cm) for smaller pompon varieties to 5½ft (1.6m) for the taller ones. The taller varieties put on a bold show at the middle and back of borders. Among them, ‘Innocence’ remains one of Andrew’s favourite pinks with its soft, misty flowers. ‘Dulwich Pink’ is darker, the flowers becoming paler with age. This is a very good do-er. Others that are vigorous growers include the pretty ‘Vagabond Prince’.
There is a wonderful range of bronze and gold colours, ideal for the later months of the year. These include golden-flowered ‘Kleiner Bernstein’ which can flower in early December. “Gardeners tend to avoid yellow flowers in the height of summer,” says Andrew. “However, by mid autumn, you need
a bit of yellow to go with coppery reds.”
Pompon varieties form compact bushes that never need staking, shrugging off the winds and rains of late autumn. With very small leaves, each neat, domed bush erupts in sprays of flowers little bigger than a one pound coin. These start to open gradually in late summer, lasting well into November. With their short height and multiple flowers, they are ideal for containers or the front of borders.
‘Anastasia’ is a charming variety smothered with soft purple flowers offset by lively green foliage. The flowers open slowly, with magenta buds co-existing alongside dark-centred flowers. Once fully opened, these turn paler towards the centre where a hint of a golden eye is revealed.
Chrysanthemums combine well in beds and borders with other plants. In autumn, there is no shortage of companions, with autumn-flowering colchicum, dahlias, nerines, asters and ornamental grasses.
Even earlier in the year, the emerging foliage sits well among tulips. Then in early summer, the foliage is sufficiently tall to hide the bulbs’ unsightly foliage. By midsummer, allium ‘Forelock’ or clumps of oriental poppies create
“Chrysanthemums do need space to develop into,” says Andrew. “However, the most vigorous varieties cope with the rough and tumble of life amongst cottage garden planting.”
Later in the summer, a good partner is the sea holly, eryngium ‘Miss Wilmott’s Ghost’. “It happily seeds around, popping up between the clumps,” says Andrew.
Developing hybrids and propagation
Andrew has raised his own hybrids, using different parent plants. Many produce unremarkable offspring. One, however, that has been particularly productive is ‘Dr Tom Parr’. This reliably produces compact, disease-resistant, tough plants unlike other hybrids. “These are smaller flowered forms that have an old-fashioned look,” he says. They flower from mid October until late November. His varieties include ‘Old Norwell’, an unusual semi-double hybrid with petals in a rain-washed red. Another is ‘Norwell Firefly’, a single with gently splayed, coral red petals surrounding a boss of golden ray florets.
Andrew propagates either by division or cuttings, in roughly equal measure. “I only use seed when breeding new varieties. Chrysanthemums have been so hybridised that 99 per cent of the seedlings tend to be inferior to the parent plants,” he explains. In spring, mature clumps are dug up, divided, and replanted. “I wait until there are signs of growth, indicating
the soil is warming up. Newly divided plants don’t do so well
in cold soil,” he adds.
Cuttings are taken from mid April until late June, once shoots exceed 2in (5cm) in length. “I plant them in free-draining compost, and stand on a window sill or in a cold frame, always out of direct sunlight,” he says. Cuttings root within three weeks, and the young plants are ready to be planted out. New plants grow surprisingly quickly, placed 24in (60cm) apart in a sheltered, sunny position. Flowering size is reached by autumn.
One added bonus that is often overlooked is fragrance. “Many are strongly and deliciously honey-scented,” says Andrew. “Others have overtones of tansy sharpness. This is not to everyone’s taste, but is quintessentially autumnal, invoking a nostalgic reaction in many.”
Chrysanthemums are an essential source of nectar and pollen for foraging insects late in the season. “In early December last year, our garden attracted comma butterflies, large pied hoverflies and bees. What other hardy plants can reliably provide food so late in the year, bridging the gap before the first winter plants take over?” asks Andrew. “With some gardeners feeling that their garden has come to its end in late August, isn’t it fantastic that you can look forward to late October for the most colourful finale?”
Chrysanthemum flower head forms
Exhibition chrysanthemums come in a range of exotic forms that include reflexed, incurved and anemone-centred. Most hardy border chrysanthemums, however, can be classified in one of four forms — single, double, semi-double and pompon. “Remember that the flowers are unaware of the classification system, and some have traits from more than one form,” explains Andrew. A typical example is ‘Dr Tom Parr’ which is at once pompon, semi-double and double. As the flowers open and mature, they change, with the category also changing. “They may open as doubles, then with time a hint of an eye appears. No longer can they be classified as a definite double.”
Single flower heads have up to five rows of flat petals borne at right angles to the stem. These surround a central yellow disc that is often green-centred. Rich in nectar and pollen, singles
include ‘Rose Madder’.
Double flower heads have many dense layers of petals that conceal the central disc. The petals vary in shape from simply strap-like to spoon-shaped — opening out at the tops to resemble miniature teaspoons. They can also be quill-shaped with slanted tips that resemble a quill. Examples of doubles include ‘Sweetheart Pink’.
Semi-double flower heads have more than five rows of flat petals arranged in varying degrees, clustered around a central yellow disc. Examples include ‘Poesie’.
Pompons are small, fully double, almost spherical flower heads. These are made up from scores of petals with flat rounded tips growing outwards from the crown. The bushes are compact
with scores of small flowers. Varieties include ‘Anastasia’
Caring for hardy chrysanthemums
Only sites that receive five or six hours of sun a day in November are suitable. The sun is low in the sky late in the year, and a sunny midsummer site could be overshadowed
by mid autumn.
These sun-loving perennials struggle on heavy, waterlogged soils. The addition of sharp sand, compost and gypsum-based fertilisers will help.
Planting is done in autumn or spring, a hole twice the size of the root ball being dug to allow for the addition of compost.
Sufficient space needs to be left for new plants to develop into. Chrysanthemums are slower to come into growth than vigorous herbaceous perennials such as catmint and hardy geraniums which could easily swamp them.
Emerging leaves need protection from slugs and snails. Andrew uses an organic, iron phosphate-based deterrent which is both effective and breaks down to a fertiliser.
In April, sprinkling a handful of Growmore round each plant encourages wiry growth. Nitrogen-rich feeds encourage lush growth, but also increase the need for staking.
Clumps are divided in March/April, once every three years. This can be done earlier if a particular variety is losing vigour
In exposed sites, staking before the foliage of taller varieties is knee-high is recommended.
Aphids on the leaves or growing tips are easily removed with
a soft soap solution.
Overcrowding is avoided to ensure a free air flow. Rust is rare because the vast majority of hybrids have stood the test of time, and are disease-resistant.
Dead-heading keeps the plants looking immaculate. However, it is not as essential in the autumn because the cooler weather means flowers die more slowly, with less mess.
Words and photography: Nicola Stocken