Plant of the Month: January

Mahonia x media 'Winter Sun' (M. japonica x lomariifolia) Common name: Mahonia Family: Berberidaceae Vital statistics Height and spread: 5m by 4m (15ft by 12ft) Form: Evergreen shrub Soil: Humus-rich, moist, well-drained Aspect: Partial shade preferred Hardiness: Hardy throughout the British Isles.

Mahonia x media Winter Sun' @ Harlow Carr

We have two plantings. The first planting is located in an open sunny position in the foliage garden, which is situated just along from the Alpine Landscape House. The other planting is in a more shaded position situated not far from the Study Centre along Fellows walk bordering the Streamside. Both plantings are mature specimens of some 15 + years.

Genus Mahonia

Mahonia is a genus of about 70 species of evergreen shrubs found in woodlands and rocky areas of the Himalayas, east Asia, Central and North America. They are common garden shrubs, grown for their attractive foliage, bright, fragrant flowers, and decorative and edible fruits. The flowers look like yellow lily-of-the-valley, and the foliage is shiny, and the individual leaflets holly-like. Some species are also favoured for their deeply fissured bark.

The fruits are blue-black, small and round, and give rise to the common name of some mahonia species of Oregon grape. They can be eaten raw or cooked. It is an acid flavour but the fruit is rather nice raw, especially when added to muesli or porridge. Unfortunately, there is relatively little flesh and a lot of seeds. The fruit ripens in early spring and good crops have often been seen on plants growing in sheltered positions. The fruit is produced in large clusters and so is easy to harvest.

Berberin, present in the roots of mahonia species, has marked antibacterial effects and is used as a bitter tonic. Berberin is also reported to have anti-tumour activity.

Mahonia was named by Thomas Nuttall after an Irish political refugee, Bernard M'Mahon who set to work in America by opening a seed shop in Philidelphia, and published the 'American Gardener's Calendar' in 1806.

Mahonia x media 'Winter Sun'

Mahonia x media 'Winter Sun' is a dense, upright, evergreen shrub with leathery, spiny, pinnate leaves and spineless stems. It is grown for its densely packed racemes of fragrant yellow flowers, which are frost resistant and are produced from autumn to early winter in horizontal or ascending racemes.

The name media comes from the word 'intermediate', meaning 'in the middle', or 'between'. It is a hybrid species of garden origin, a cross of M. japonica and M. lomariifolia, and the selected form of 'Winter Sun' was raised by the Slieve Donard Nursery in Northern Ireland.

There are several other cultivars including 'Lionel Fortescue' and 'Charity', both of which have, like 'Winter Sun', been awarded an AGM.

AGM

The RHS Floral B Committee awarded Mahonia x media 'Winter Sun' an Award of Garden Merit and described it as: Medium-sized evergreen shrub of upright growth, with long, spiny, pinnate leaves. Flowers small, bright yellow, fragrant, in clusters of erect racemes

Cultivation

Mahonia x media will take full sun but prefers to be in shade or a semi shaded area. It is best in a moist but relatively fertile, humus-rich soil, including chalk soils. It is frost hardy, and the scented flowers are frost resistant, but young growth may be damaged by late frosts.

The shrub does tend to get leggy but can be pruned, large plants can be stooled to about 18" and will regenerate well, it is best though to prune over a 3 year period taking out about a third of growth each year. Pinching out the spent flowering shoots of smaller plants can encourage a more even habit.

Mahonia x media is generally pest and disease free.

Propagation

Propagation is by leaf bud or semi-ripe cuttings in summer.

Seed can be sown outdoors in the autumn as soon as it is ripe, but as this is a hybrid, they will probably not come true.

Another method is by the division of suckers in spring. Whilst they can be placed direct into their permanent positions, better results are achieved if they are potted up and placed in a frame until established.