How to grow hardy chrysanthemums

Val Bourne / 24 September 2012

Hardy chrysanthemums flower in October and November, and few flowers look as cheerful in autumn light. Find out how to grow them for autumn colour.



Hardy chrysanthemums flower in October and November so they make good additions to the border or the cutting garden for few flowers last as long in water, or look as cheerful in autumn light.

However, many of the varieties sold in garden centres have been raised under glass, so are not truly hardy, so always buy from a specialist nursery raising hardy stock.

Forget large, showy blooms: most ‘hardies’ bear sprays of delicate flowers that fit into a border well.

Most are easy and resilient and they were planted widely in the past as cut flowers, often surviving as unnamed varieties in older gardens. They are making a comeback in recent years and are extremely useful for late colour.

When to plant

Plant in October without fear, unless you have heavy clay. If so, keep your pots in a dry position, fleece in winter and plant in spring.

Where to plant

Chrysanthemums all require a sunny position that remains warm and sunny in autumn.

They also require space, as they are slow to start into growth, so could easily be smothered by earlier flowering plants like nepetas and hardy geraniums.

For this reason, I grow mine among similarly late-flowering plants including colchicums and nerines, which look especially good with pink and magentas chrysanthemums.

When to divide

Some varieties of chrysanthemums endure for many years without division. Others may need dividing as they are losing vigour, or you may need more plants. If so, divide in May as new growth has got going. Replant the strongest pieces straight back into soil enriched with blood, fish and bone spacing them just over a foot apart. Or put up your divisions and plant out in early September.

When to take cuttings

Chrysanthemum cuttings can also be taken in may. Select strong shoots about two or three inches in length (5 - 7 cm) and insert them into gritty compost. Place in shade and warmth. Pinch out as the cuttings race away.

When to thin

Some do run about, but others are clump forming. Hardy chrsyanthemums are best thinned in late May, but only if the clumps look congested.

Cut out some of the weaker stems and water well if the weather has been dry, for these plants are used to a damp, warm Asian summer so they need moisture to grow well.

Caring for Chrysanthemums

I don’t generally stake as hardy chrysanthemums have strong woody stems, but I am careful not to feed them with quick-fix nitrogen feeds as I prefer wiry growth. Adding extra nitrogen will make them lusher and then staking may be required. Use blood, fish and bone or Growmore every spring, as a slow-release feed.

Wildlife

The single varieties sustain late-flying bees and butterflies with their honey-tansy scent.

Pests

Slugs can be a problem in spring, just as the young shoots emerge. Read our guide to controlling slugs and snails.

Grow with…

Hardy chrysanthemums are best at the front of the border as they do not get swamped. They can either follow asters, or be placed in front of other autumn flowering plants. The oranges and warm shades blend well with asters, or they can be used in front of grasses.

Varieties

Colours range from pale and milky, to truly vibrant. Both shine as long as they can pick up the late sunshine so opt for a warm south, or south-west facing position. Good doers that endure from year to year include ‘Vagabond Prince’ (a semi-double pink), the true ‘Anastasia’ (rich purple-to-magenta buttons), ‘Mrs Jessie Cooper’ (a crisp single magenta-pink ) and ‘Golden Greenheart’ - a semi-double green-centred soft bronze.

‘Clara Curtis’
A graceful single-pink heritage variety which always looks terrific with hardy nerines (N. bowdenii) in a sunny border in September. 75 cm/30 in.

‘Julia Peterson’
A cluster of small buttons in deep purple-pink between September and November. 60 cm/2ft. Bred and named by Clive Hester in Gloucestershire and very pretty.

‘Emperor of China’
One of the loveliest, with double silver-pink flowers set off by foliage which reddens in autumn. Petals quilled and taller than most, flowering in November. Can be up to 120 cm/4ft - more typically a foot shorter.

‘Nantyderry Sunshine’
Clusters of small bright-yellow flowers from October - a rambling habit and a short plant 40 cm/16 in.

‘Chelsea Physic Garden’
Very late, so needs a warm position to produce its fully petalled dusky, orange-red flowers with bronze overtones. Extremely hardy though. Up to 90 cm/3ft.

‘Rose Madder’
Very resilient, brownish-pink single which flowers in October. 90 cm/36 in.

‘Rosetta’
Double-pink flowers with green eyes surrounded by a darker pink halo. This is earlier than others and can begin flowering in August. 90 cm/3ft.

‘Paul Boissier’
Green-eyed rich russet-orange. Bred by Perry in 1945 and a great survivor. 90cm/3ft.

‘Burnt Orange’
Very special and the only hardy with spoon-shaped petals in orange and red. These are set off by jagged, grey foliage, so this needs good drainage and full sun. 90 cm/3ft.

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