The cut chrysanthemum is a familiar flower in supermarkets and florists, and is grown commercially in huge quantities.  It is a traditional garden flower, and while its popular appeal has waxed and waned many times over the decades, it retains a strong following amongst its enthusiasts and exhibitors. Chrysanthemum cutting beds still take pride of place in many allotments.

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The colourful flowers make a welcome late summer and autumn show in borders and beds, and they provide perfect cutting material for bouquets and indoor floral arrangements.

Chrysanthemums have been cultivated, admired and included in various art forms in China for at least 3,000 years, and more than 500 cultivars were known there by 1630. Many of the familiar shapes, colours, and varieties were created in Japan, where the chrysanthemum arrived around 400 AD and quickly became part of popular and religious culture. The flower adorns the Imperial Seal of Japan, there is an award for chivalry called the ‘Order of the Chrysanthemum’, and the monarch sits on the Chrysanthemum Throne.

One of the first records of the plant in Britain was in the Botanical Magazine of 1796, when a specimen brought from Paris to Kew Gardens was featured. The western name, chrysanthemum, comes from the Ancient Greek ‘chrysos’ (gold) and ‘anthemon’ (flower), reflecting that the original species from which most of the modern hybrids and varieties developed were a rich golden yellow colour.

Plant Overview

Common Name Chrysanthemum, mums, chrysanths
Scientific Name Chrysanthemum indicum, C. sinese, C × grandiflorum and many others
Plant Family Asteraceae
Origin Asia and north-eastern Europe
Height Up to 1.5 metres depending on variety
Light Sunny position
Temperature A few types to -15°C, but most are not frost hardy
Hardiness Mostly tender but some hardy and half hardy types
Soil Rich loam, clay or sandy soil; any normal garden soil pH
Fertiliser Nitrogen based fertiliser in June and potash based fertiliser at flowering
Propagation Division, seed, cuttings
Pests Aphids, leaf miners, Chrysanthemum white rust and other infections
Difficulty Easy

Chrysanthemum Varieties

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Chrysanthemum flowers come in various forms, from simple daisy shapes to complex pompons and buttons. Many hybrids and thousands of cultivars have been developed for gardens and cut flower production. Perhaps the most important hybrid is Chrysanthemum x grandiflorum, derived originally from the species Chrysanthemum indicum, but also historically involving a number of other species, some of the earliest of which were probably never properly recorded.

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Nearly 150 types of chrysanthemum have gained the Royal Horticultural Society’s Award of Garden Merit. Garden centres and nurseries sell many of the cultivars, including some widely available varieties and mixtures. Each of the specialist chrysanthemum nurseries also produces its own favourites. While new ones continue to be introduced to the market each year, some of the old favourites have now been around for many decades.

With such a wide variety of flower form and colour available, the National Chrysanthemum Society produced a classification system, and each registered cultivar has been allocated a classification number, which is often given after the name on specialist nursery lists. For example, Chrysanthemum ‘Joyce Frieda’ has the code number 13bY. The number 13 refers to the flowering time and classification group, 1 meaning it is mid-season flowering and 3 categorising it as an incurved bloom. The letter b defines the size of bloom, which is medium for ‘Joyce Freda’, and the second letter (Y) describes the colour, in this case yellow.

Chrysanthemum flowering time is defined as early (September), mid (October) or late (November).

The category of flower type depends on the arrangement of petals on the flower and the shape of the bloom, such as whether the petals are reflexed or incurved, and whether the blooms are single or pompon shaped. The flower size is simply divided into small, medium and large categories.

There are six principal chrysanthemum colour groups, bronze, pink, purple, red, yellow and salmon. Each of these can be further classified as standard, ‘light’ or ‘deep’. There are also other groups called ‘white’, ‘cream’ and ‘other colours’, meaning there are 21 possible colour descriptions overall.

Some of the commonest groups include:

  • 28: The early-flowering outdoor pompons
  • 28b: The semi-pompons, or Japanese pompons
  • 29: The early-flowering outdoor spray chrysanthemums
  • 29d: Single chrysanthemums
  • 29k: The so-called Korean hybrids, which are a cross between Chrysanthemum coreanum and C × grandiflorum ‘Ruth Hatton’

Here are just a few of the popular varieties of chrysanthemum.

Chrysanthemum ‘Max Riley’

‘Max Riley’ is a half-hardy perennial that grows up to 1.2m in height. It has long-stemmed, bright yellow incurved petal flowers up to 11cm in diameter from September. It is well known for being a reliable flowerer in the garden. ‘Bronze Max Riley’, which is a darker yellow, is also widely available.

Chrysanthemum ‘Clapham Delight’

This cultivar has large, pure white flowers with tightly incurved petals. It has a neat form and thick, sturdy stems.  It is one of the best choices for white blooms for exhibition purposes.

Chrysanthemum ‘Music’

This very reliable outdoor chrysanthemum has bright rose-pink flowers from September onwards. The flowers have incurved petals, and they are excellent for cutting and flower arrangements.  It grows up to 1.2m in height.

Chrysanthemum ‘Evesham Vale’  

‘Evesham Vale’ has fully double, rich-red blooms with reflexed, wavy petals and does well in the border or allotment. The flowers are dramatic and long lasting in the vase if cut just as the buds are opening. It flowers from late September through October and November, until the first frosts of winter.

Chrysanthemum ‘Early Yellow’

‘Early Yellow’ is a long-lasting, prolific, perennial variety with daisy-like, canary-yellow, single flowers with a prominent golden centre. It is amongst the earliest chrysanthemums, with flowers from July. It is hardy in the south of the UK and should survive a normal winter outdoors and come again in the following summer. It grows up to 90cm tall.

Chrysanthemum ‘Pompon Yellow’

This cottage garden favourite is compact and half hardy, and it produces an abundance of sprays of almost spherical, fully double, 8cm, yellow pompon flowers. It is relatively easy to grow in the border or patio containers. It will continue flowering from September through to the first frosts. It will grow to a height of 75cm.

Chrysanthemum ‘Spartan Fire’

‘Spartan fire’ has fiery red, reflexed flowers with a flash of gold on the underside of the petals. They are as striking in a vase as they are in the flower border. They are hardy enough to overwinter most years, especially in the warmer parts of the country. The plant will grow up to 90cm tall.

Chrysanthemum ‘Golden Rain’

This is an unusual form of chrysanthemum, with short, incurving inner florets and very long and slender outer ones. These spidery outer florets can reach 15cm in length, and give the golden-yellow flower an elegant and dramatic look on the plant, or in a bouquet or flower arrangement. The flowers appear from November on very tall spikes up to 1.5m in height. It has the Royal Horticultural Society Award of Garden Merit.

Chrysanthemum ‘Mrs Jessie Cooper’

A variety of Chrysanthemum rubellum, this is another Royal Horticultural Society Award of Garden Merit winner. It is a hardy variety with long-lasting, daisy-like, dusky-red, single flowers with a very prominent yellow centre. It flowers from August to November and can reach a height of 80cm.

Chrysanthemum ‘Heather James’

‘Heather James’ is a late variety that grows up to 1.5m. It has medium-sized, reddish bronze flowers with incurved petals.  It blooms through November.

Chrysanthemum Care

The appropriate care for a chrysanthemum depends on whether it is a garden hardy variety or an exhibition type. Garden hardy perennials are capable of wintering in sheltered areas across much of the UK, though some are only fully hardy in the south, or near the coast. Exhibition varieties are less sturdy and need to be overwintered indoors in a cool greenhouse, sometimes with the provision of artificial lighting.  Late chrysanthemums need to be grown under glass to bring them into flower later in the season.

In general, the exhibition types are grown by enthusiasts, and the amateur gardener will stick to the hardy varieties, so this article focuses on growing these early chrysanthemums that can be kept outside all year round in warmer areas. There is still plenty of choice within this selection, from taller varieties that need staking and provide excellent sprays of cut flowers to dwarf cultivars that are great in containers as well as borders.

Newly bought or propagated plants should be hardened off in April in a cold frame or by moving them during the daytime to a sheltered spot near the house. They can be planted out at 40cm centres into the border in mid-May. Dwarf varieties in containers can be planted more closely. The plants should be handled by the root ball rather than the foliage or stem, both of which are easily damaged at this stage.

They will do best in a sheltered and sunny position. Enrich the soil in the winter before planting by digging in plenty of organic matter such as garden compost or well-rotted manure. Add blood, fish and bone to the ground at around 100g per square metre a couple of weeks before planting. Plant into the border so that they are at the same level as they are in the pot.

After planting, water daily and generously for a couple of weeks to avoid stress while the plants establish a good root system.

To encourage flower production in spray cultivars that have large, multiple flower heads, the growing points can be pinched out in late May or early June when they have reached approximately 25cm tall to encourage more branching. This is called ‘stopping’, and is a traditional technique for chrysanthemum growing.

For other types, large single blooms can encouraged at the expense of the number of flowers by removing all side buds and shoots so that only the terminal flower bud on each shoot remains.

The taller chrysanthemums can become top heavy in flower, and the stems are not always sturdy enough to support the flowers, especially if there are heavy autumn showers and gales. Some support is therefore required, either as individual stakes or as netted twine tied around a group.

After flowering, the stems should be cut down to 20cm to leave an overwintering stool. In mild areas where frosts do not get below -5°C, the stools can largely be left to their own devices over winter, though a mulch of bark chips or garden compost will provide some insurance. When there are likely to be more severe frosts, it is wise to take further precautions and provide a deeper mulch with straw or fleece, or better still to lift and store the stools in an unheated greenhouse or a cool conservatory. To do this, lift the stools from the ground and shake the soil from the roots. Remove any green shoots and leaves, and store the stools in a shallow tray on top of a 5cm layer of multi-purpose compost with a further light covering of un-compacted compost on top of them. They should not be watered, though the compost should be kept slightly moist.

Light requirements

They do best in a sunny but sheltered position in the garden.

Watering

Water well at planting and to keep the soil moist but not waterlogged thereafter.

Soil conditions

Any well drained and organic rich garden soil is suitable, and they are not at all fussy about soil pH. They will even tolerate relatively heavy clay soils, though these are best ameliorated with plenty of organic matter to reduce the risk of waterlogging and rot.

Fertilisers

A ‘top dressing’ of nitrogen-rich fertiliser such as sulphate of ammonia or poultry manure pellets can be applied at approximately 35g per square metre in June to encourage general growth. A light dressing of blood, fish and bone or diluted tomato fertiliser in September will help maximise the number and quality of blooms.

Re-potting

Most types of chrysanthemum will grow in large pots, at least 35cm in diameter, though some are better suited than others. The less hardy types can be taken outside for the summer and early autumn to stand on the patio, or pots of the earlier flowering half-hardy varieties can be plunged into the soil. This is a good way of adding colour to the herbaceous border in early autumn without too much additional work, but they need to be brought back indoors when there is a risk of frost.

Fill containers with John Innes No 2 compost and for pots, use just one plant per container. Multiple dwarf chrysanthemums can be planted in larger containers. Water them in well, and include a stake for taller varieties.  Keep them in a cool conservatory or greenhouse, harden off, and then place them outside in a sunny, sheltered spot once all risk of frost has passed.

Water the container well throughout the summer and give them a balanced feed every two weeks from until the flower buds appear.

The plants should be cut back when they have finish flowering, and stored in a frost-free place over winter with minimal watering to keep the compost just slightly moist.

Hardy varieties can be grown in containers that remain outside all year round, but the pot will need to be protected from the frost with bubble-wrap or plenty of fleece and straw so the roots near the outside are not affected.

Looks good with

Chrysanthemums are generally grown as mixed displays in their own right, or as a late summer and autumn addition to the herbaceous border when most other flowers have finished. A colourful selection of chrysanthemums can be complemented by a more muted foil of other daisy-like flowers, especially asters, or they look good against an autumn background of tall grasses such as Molinia, Miscanthus, and Pennisetum.

 

Pruning

Chrysanthemums do not require pruning as such, but as described above, flower numbers, size and timing can be influenced by stopping and pinching out growing points and flower buds.

At the end of the flowering season, the plant should be cut down to a 20cm stool for overwintering.

Chrysanthemum Propagation

chrysanthemum
There are several methods of propagation for chrysanthemums.

The most reliable method is by taking basal cuttings from the previous year’s plants in early March as new growth appears from the crowns. 8cm cuttings should be taken from as close as possible to the crown. These should be placed in individual pots, watered well, and grown on at 10°C for planting out later in the summer.

Alternatively, well-established plants can be divided in spring, after the year’s new growth has appeared. Use a sharp, sterilised knife to divide the root ball and ensure each portion has roots and stem growth.

A few types of chrysanthemum can be grown from seed, which is generally available from the larger seed merchants and specialist suppliers. These should be sown into a good quality seed compost in trays and kept at a constant 15°C. They should germinate within a fortnight. They can be potted on, hardened off in May, and planted out to flower in the same year.

Common Chrysanthemum Problems

Pests

Aphids and leaf miners are common chrysanthemum pests, and they can be treated with sprays or organic alternatives. Leaf and bud eelworms can damage stock that has not been heat-treated by the original grower.

Earwigs sometimes damage blooms, and can be controlled by hand collection in an upturned pot of straw on the supporting stake. Capsid bug and glasshouse red spider mite are occasional pests of indoor chrysanthemums.

Diseases

Fungal diseases such as chrysanthemum white rust, grey mould and rots can be very damaging to the plants, and they are difficult to control. Powdery mildew can affect plants that are left with dry conditions. Chrysanthemums are also prone to a number of viral diseases that can cause deformity, stunting and yellow or brown leaf markings.

FAQs

Q I have heard growing chrysanthemums on the allotment brings a sort of natural insecticide that protects the vegetable crops. Is this true?

A

There is an element of truth in that old wives tale, but it is unlikely that the plants’ innate insecticidal qualities will protect other plants around them. Chrysanthemums are a source of pyrethrum, a natural insecticide. Extracts from the flowers are still used in some insecticidal preparations that are applied as a suspension in water or oil, or as a powder. Pyrethrin attacks the nervous systems of insects and in sub-lethal doses it has a repellent effect, which is quite efficient against mosquitoes.  Although harmful to fish, pyrethrin is less toxic to mammals and birds than many of our more recent synthetic insecticides. It biodegrades in the soil and decomposes rapidly on exposure to light, so it is not persistent in the environment.

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