Chrysanthemum,propagation and uses

Chrysanthemums, sometimes called mums or chrysanths, are flowering plants of the genus Chrysanthemum in the family Asteraceae. They arenative to Asia and northeastern Europe. Most species originate from East Asia and the center of diversity is in China.There are countless horticultural varieties and cultivars.The name "chrysanthemum" is derived from the Greek words chrysos(gold) and anthemon (flower

Description Wild Chrysanthemum taxa are herbaceous perennial plants or subshrubs. They have alternately arranged leaves divided into leaflets with toothed or occasionally smooth edges. The compound inflorescence is an array of severalflower heads, or sometimes a solitary head. The head has a base covered in layers of phyllaries. The simple row of ray florets are white, yellow or red; many horticultural specimens have been bred to bear many rows of ray florets in a great variety of colors. The disc florets of wild taxa are yellow. The fruit is a ribbed achene

Cultivation

There are many different forms of chrysanthemum and ways of growing them. Some methods of cultivation are easy, others more complicated. For example, late chrysanthemums need to be grown under glass to bring them into flower later in the season. Likewise cut-flower production under glass uses curtains and lights to mimic the correct season to produce flowers all year round – a whole world of technical complexity in itself. Over the years the RHS has conducted numerous chrysanthemum trials, and the reportsof these are available free on-line; an invaluable resource for chrysanthemum growers.

So, in order to be straightforward, this advice page covers what is known as the early chrysanthemums. As well as taller ones (often grown for cut flowers) that will need staking, many dwarf cultivars are available for use in containers and borders. These can be grown outside all year round in mild areas. On cooler sites, however, they do need to be lifted and protected from wet, cold winters.

Planting out

•             Newly propagated young plants need to be hardened off in April by being placed in a coldframe

•             Plant out in mid-May, once the risk of frost has past. Space them 45cm (18in) apart

•             Choose a sheltered sunny position; ideally improve the soil by digging in well-rotted organic matter such as homemade compost during the winter at about 10kg per sq m (25lbs per sq yd), usually one to two bucketful per square yard or metre. Then fork in a dressing of general fertiliser (100g per sq m (4oz per sq yd) of growmore or blood, fish and bone) towards the end of April. A 'top dressing' of nitrogen-rich fertiliser is often applied in June to encourage growth (35g per sq m (1oz per sq yd) of sulphate of ammonia, or for organic gardeners 70g per sq m (2oz per sq yd) of dried poultry manure pellets)

Disbudding

•             Depending on habit and flower type, the plants will require pinching out and staking. Pinching out (stopping) the growing points in late May or early June encourages branching

•             Large single blooms (often called 'disbuds') are encouraged by maintaining the main central bud and removing all side buds and shoots so that only the terminal flower bud on each shoot remains

•             Spray cultivars can produce a more even spray formation by removing the terminal flower bud

•             Flowering times and optimum stopping times can vary according to the cultivar, seasonal and regional variations. Further details can be found in the catalogues of specialist growers

Cutting back and over wintering

•             After flowering, cut back the main stem to about 20cm (8in) to produce what is known as a stool or rootstock

•             On average early chrysanthemums have a hardiness rating of H3 (which has a minimum temperature of -5°C) so, in mild areas, they can be left outside over winter, with a good covering of coarse organic matter such as homemade compost or bark chips as a protective mulch. A well-drained site is preferable

•             On cold, exposed or badly drained sites, lift and store the stools over winter in frost-free conditions, such as a frost free greenhouse or a cool conservatory

Preparation for overwintering

•             Lift the shortened plants from the ground or remove from their pots. Ensure that the surplus soil in shaken from the roots

•             Tidy up the stools by removing green shoots and leaves leaving just the stems shortended to 8cm (3ins). Then label each stool as they will all look similar at this point

•             Place the stools in a shallow tray on top of a 5cm (2in) layer of multi-purpose compost, ideally peat-free, and then give the roots a light covering of compost once packed in the tray

•             Do not water them in and keep them cold but frost free over winter, such as a heated greenhouse or cool conservatory

•             Keep the compost just moist through the winter

Propagation

There are several methods of propagation for chrysanthemums.

Seeds

Some types of chrysanthemums, Koreans for example, are available as seeds but most grower prefer to grow named cultivars. These are produced from divisions or basal cuttings.

Division

Old root stocks (stools) can be divided in the spring, once new growth has started. However, for stronger healthy plants, it is recommended that fresh stock is propagated each year from basal cuttings in spring from last year’s stock.

Preparation for taking cuttings:

•             In early January, bring the over-wintered stools into a moderately heated greenhouse/conservatory at 7-10°C (45-50°F)

•             Water the trays so that the compost is thoroughly moistened and then keep it just moist

•             This will encourage the basal shoots to grow, and within three to four weeks, there will be strong young green shoots ready for taking cuttings. Cuttings can be taken from mid-February onwards

Cultivar Selection

Here is a selection of 10 AGM plants as selected by plantsman Graham Rice and those listed on the RHS Plant Selector.

Because of the wide variety of form available, The National Chrysanthemum Society has a classification system for chrysanthemums. Early chrysanthmums are mostly in the groups 28-29, the number is listed after the cultivar;

Pests

Aphids and leaf miners are common pests. Leaf and bud eelworms can damage stock that has not been heat-treated. Earwigs sometimes damage blooms. Capsid bug and glasshouse red spider mite are occasional pests.

Disease

Rust diseases, especially Chrysanthemum white rust, can be very damaging and hard to control. Powdery mildew can be damaging in dry conditions. In wet weather grey moulds and other fungal rots can be severe. Several virus diseases may cause stunting and leaf markings.

Ornamental uses

 'Enbee Wedding Golden' and 'Feeling Green'

Modern cultivated chrysanthemums are showier than their wild relatives. The flower heads occur in various forms, and can be daisy-like or decorative, like pompons or buttons. This genus contains many hybrids and thousands of cultivars developed for horticultural purposes. In addition to the traditional yellow, other colors are available, such as white, purple, and red. The most important hybrid isChrysanthemum × morifolium (syn. C. × grandiflorum), derived primarily from C. indicum, but also involving other species.

Over 140 varieties of chrysanthemum have gained the Royal Horticultural Society's Award of Garden Merit.

Chrysanthemums are divided into two basic groups, garden hardy and exhibition. Garden hardy mums are new perennials capable of wintering in most northern latitudes. Exhibition varieties are not usually as sturdy. Garden hardies are defined by their ability to produce an abundance of small blooms with little if any mechanical assistance, such as staking, and withstanding wind and rain. Exhibition varieties, though, require staking, overwintering in a relatively dry, cool environment, and sometimes the addition of night lights.

The exhibition varieties can be used to create many amazing plant forms, such as large disbudded blooms, spray forms, and many artistically trained forms, such as thousand-bloom, standard (trees), fans, hanging baskets,topiary, bonsai, and cascades.

Culinary uses

Yellow or white chrysanthemum flowers of the species C. morifolium are boiled to make a sweet drink in some parts of Asia. The resulting beverage is known simply as chrysanthemum tea , pinyin: júhuā chá, in Chinese). In Korea, a rice wine flavored with chrysanthemum flowers is called gukhwaju

Chrysanthemum leaves are steamed or boiled and used as greens, especially in Chinese cuisine. The flowers may be added to thick snakemeat soup  to enhance the aroma. Small chrysanthemums are used in Japan as a sashimi garnish.

Insecticidal uses

Pyrethrum (Chrysanthemum [or Tanacetum] cinerariaefolium) is economically important as a natural source ofinsecticide. The flowers are pulverized, and the active components, called pyrethrins, which occur in the achenes, are extracted and sold in the form of an oleoresin. This is applied as a suspension in water or oil, or as a powder. Pyrethrins attack the nervous systems of all insects, and inhibit female mosquitoes from biting.

Environmental uses

Chrysanthemum plants have been shown to reduce indoor air pollution by the NASA Clean Air Study.