Choose and plant chrysanths this spring for a brilliant display in autumn
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| Chrysanthemum 'Syllabub'
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'Plant young plants in spring – they're perfectly frost-hardy as long as they've been hardened off – and water in well with a liquid feed.'
As our climate changes and the autumn season extends closer to Christmas, allowing later perennials to shine for longer, and as gardeners remember how many lovely chrysanthemums are tough enough to grow easily outside – the realisation dawns: these are great plants! They harmonise well with other perennials and with garden shrubs too. As the autumn leaves of deciduous shrubs colour up, chrysanths are at their best and there seems to be a natural harmony between the russet and gold autumnal foliage and the flowers of spray chrysanthemums.
There are many different forms of chrysanthemums – the National Chrysanthemum Society classifies them into more than 80 different types! Unless you're a serious exhibitor, however, there are only a few general types that you really need to think about: Koreans, hardy sprays, Japanese pompoms, bush chrysanths and those huge, unbelievable ones that are almost as big as footballs (and are easier to grow than you might imagine).
Sprays and disbudded
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| 'Sutton White' bloom: on offer in Gardens Monthly Spring issue
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It's also useful to distinguish between sprays and 'disbudded' chrysanths. Sprays are those that carry a branching head of small or medium-sized flowers; they have the most impact and the longest season in the garden and they blend well with other flowers in the vase. They usually grow this way naturally, but branching can also be encouraged by pinching out the shoot tips.
'Disbudded' chrysanths have much larger flowers which are individually dramatic and for which the size and the form of the individual blooms are important. In fact, the size is usually enhanced by the removal of the buds below the main flower (disbudding) so that more of the plant's resources go toward producing a small number of especially impressive flowers.
Korean chrysanths
Korean forms are the original hardy, tough-as-nails, garden chrysanthemums - derived from what used to be called Chrysanthemum coreanum (now C. zawadskii). Many were originally bred in the 1930s in Bristol (Bristol, Connecticut that is), where the winter temperature can go down to -26ºC (-15ºF). Often 90-120cm (3-4ft) tall, occasionally taller, and branching naturally into attractive sprays, the flowers may be single or come in a range of different double forms from neat pompoms, to blowsier and shaggier doubles - and even 'spider' forms in which the petals are rolled into slender tubes. All are naturally prolific, some will flower as late as December, and they come in just about every colour except blue. The singles are often especially attractive and combine prolific blooms with a natural look that many gardeners appreciate. Rubellums, slightly less hardy and with a tendency to run at the root, are also now usually included among Koreans.
Koreans are enjoying a welcome resurgence as gardeners appreciate their many qualities again. Some can become rather tall and straggly, but a June pinch or thoughtful staking usually solves the problem. Good varieties include 'Clara Curtis' (single pink), 'Emperor of China' (double quilled, deep pink), 'Ruby Mound' (double, red, AGM), 'Sea Urchin' (spider, yellow, AGM), 'Wedding Day' (single, white).
Garden sprays
The hardy garden sprays are the modern descendants of the Korean chrysanthemums and are also partly derived from other modern greenhouse spray varieties. Although less tough than the Koreans – they don't really need to be that tough – these are outdoor varieties, with single, double or anemone-centred flowers, featuring a branching habit, prolific bloom and improved flower form.
The garden sprays usually seen are members of a number of series – similar varieties from the same breeder differing mainly in flower colour. The Pennine Series, bred in Derbyshire and which includes in its ranks an amazing 32 varieties which have received the much-prized Award of Garden Merit (AGM) from the RHS, is especially impressive. Unfortunately, many of the older members of the Pennine Series are no longer available. Good varieties include Pennine Series (32 AGMs), Spartan Series, Trojan Series, Enbee Wedding Series (eight AGMs).
Japanese pompoms
This small group of shorter-growing, double-pompom flowered varieties is derived from a few tiny cuttings that arrived from Japan in a matchbox in the late 1950s. The plants are short, the dainty, button-like, double flowers are prolifically produced, and these chrysanths also feature unusually small, neat and attractive foliage.
The pink 'Mei-kyo' was the original introduction from Japan and a number of other colours have been derived from it over the years. The buttery 'Nantyderry Sunshine', found in a garden in Wales, is especially bright and impressive and probably the pick of the bunch. Good varieties include 'Mei-kyo', 'Bronze Elegance', 'Purleigh White' and yellow 'Nantyderry Sunshine' (AGM).
Large-flowered types
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| 'Sam Oldham' bloom: on offer in Gardens Monthly Spring issue
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Large-flowered chrysanthemums vary enormously. Many of these are intended solely for showing and they are grown in the greenhouse, or in pampered conditions outside, to produce the very best flower forms. This is an art practised by chrysanthemum devotees whose blooms compete in shows where the tiniest failing in quality can make all the difference between success and failure.
The rest of us can afford to be less fussy and enjoy 'incurved' and 'reflexed' flowers for cutting for the house or for the village show. 'Incurved' chrysanths have their petals arched upwards towards the top of the flower – the classic chrysanthemum shape; in 'reflexed' varieties the petals arch outwards and downwards.
There are many excellent varieties, such as those in the Gardens Monthly reader offer (Spring issue, page 25, on sale now) a good starting collection of reflexed and incurved types from chrysanth specialist Woolmans (link below).
Growing as annuals
Bush chrysanths
For the front of the border, or especially as individual specimens in containers, bush chrysanths are ideal. They make rounded mounds of colour 45-75cm (18-30in) high or more, depending on variety, and the intensity of colour is extraordinary. They naturally branch repeatedly to develop their even domed shape so you never need to pinch them out. A great deal of breeding work is going on in this group, with new varieties appearing all the time. The Japanese pompoms can also be pinched to keep them shorter and create a more mounded habit suitable for containers.
Good varieties: Showmaker Series (75cm/30in – for the middle ground in borders and for large containers) 'Belgian Mums' (18-20in/45-50in – for formal gardens and smaller containers).
Greenhouse chrysanthemums
Using the greenhouse opens up the possibility of growing a whole range of additional late varieties. These include prolific, but less robust, spray types - singles, doubles and spiders - as well as exhibition varieties whose large and fully-petalled blooms benefit from protection to remain pristine and undamaged by weather.
Greenhouse chrysanths can be grown in pots or in the soil, but growing in pots helps prevent the build up of soil-borne diseases. The crucial factors are: good soil and good drainage; regular watering and feeding; good ventilation; thoughtful support; pinching to suit the individual variety and pest and disease control. The book Week-by-Week Cultural Guide published by the National Chrysanthemum Society is very useful for beginners to the art of growing top-quality greenhouse chrysanthemums. Start with a collection of trustworthy varieties from a specialist, such as Woolmans.
Sun, soil and drainage
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| 'Eagle' spray from the Pennine Series: on offer in Gardens Monthly Spring issue
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All garden chrysanthemums appreciate three things: sunshine, rich soil and good drainage. Sunshine encourages plenty of flowers and stout growth which is not straggly; rich soil ensures that the plants thrive, the foliage looks good, the flowers develop to their full potential and that plants bulk up well and retain their lower leaves; good drainage is crucial in ensuring they come through the winter well – chrysanthemums hate wet winter soil.
Spring planting
Plant young plants in spring – they're perfectly frost-hardy as long as they've been hardened off – and water in well with a liquid feed. Taller Koreans and sprays will need support from summer onwards. Use brushwood, canes and string or purpose-made steel supports.
June prune
One useful trick to remember is that you can reduce the height of all hardy chrysanths by snipping them back in June. This encourages them to branch out, reduces their height noticeably and hardly postpones flowering; often flowering is not delayed at all. Or you can snip back shoots at the front of the clump to encourage flowers lower down for more of a full-frontal display.
Pest and disease prevention
The most serious chrysanthemum problems are usually encountered when a large number are grown together; troubles tend to be fewer in mixed borders. Aphids are often the only problem, but powdery mildew can be troublesome in hot, dry summers.
The worst chrysanthemum disease, however, is white rust. Most prevalent in cool, damp conditions, it first shows as yellow spots on the upper surface of the leaves while immediately underneath each spot is a brownish pustule which then turns white. White rust can be very destructive and spread quickly so treat it by nipping off and burning leaves at the first sign, and alternate between rust fungicides.
Even if you grow a number of varieties for cutting, it pays to spread them around the garden, rather than grow them together to help prevent the spread of disease. Large-flowered varieties, however, are perhaps best grown together as the staking, disbudding, and specific care they require can be provided more easily.
Plant chrysanthemums with...
Korean, spray and Japanese pompoms planted out in beds and borders associate well with a wide variety of other autumnal plants. Backed by shrubs like
Berberis,
Viburnum, maples and
Amelanchier which colour well in autumn, or the fruits of
Pyracantha and
Cotoneaster, an autumn-themed mixed border – or just a corner, perhaps – can blend chrysanthemums with other perennials. One of the attractions of chrysanthemums is that their colour range is so large that choosing companions whose colours work well with other perennials is not hard.
Good companions include Michaelmas daisies (Aster novi-belgii) as illustrated on page 21, which also come in a vast range of colours. Other aster species – Aster ericoides in particular – with its clouds of tiny flowers, billow around the bolder chrysanthemums. Japanese anemones also make ideal partners, as do late kniphofias, together with other late daisies like boltonias and perennial sunflowers. Sedums are also good
to plant in front, along with liriopes.
* Images of 'Eagle', 'Sam Oldham' and 'Sutton White' from Woolmans.
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