Mahonia

These winter-flowering shrubs make impressive, statuesque features in borders, writes Miranda Kimberley.

Mahonia aquifolium  - image: FlickR/Tim Dobbelaere
Mahonia aquifolium - image: FlickR/Tim Dobbelaere

Mahonia are statuesque evergreen shrubs that provide structure at the back of borders and cheer up the winter gloom with their bright yellow flowers. They have attractive glossy leaves, resembling spikey-edged holly, and blue-black berries that provide welcome fodder for birds.

They reside in the Berberidaceae family and are closely related to Berberis, though distinguished by having pinnate leaves and spineless stems. The flowers can be yellow or white, globular or bell-shaped, and are often fragrant. They are borne in racemes, all radiating from a central point, creating a dramatic feature. Flowering lasts for many weeks.

There are around 70 species of Mahonia, but four species are widely grown in the UK, with quite a few hybrids and varieties. One of the first into flower is M. x media, in November. 'Charity', with its upright habit, is the best-known variety, but some people suggest that 'Wintersun' has a better fragrance and that 'Lionel Fortescue' has more attractive flowers.

M. aquifolium is good as a ground-cover plant or for understorey planting. It is known as the Oregon grape because it has round blue-black fruits. It has a suckering habit, so spreads well in shady spots.

M. lomariifolia Award of Garden Merit (AGM), unlike the other species, is slightly tender. Its characteristics are elegant foliage, scented flowers and fissured bark. An exciting new variety is M. nitens 'Cabaret' PBR, which blooms from late August until November. The flower buds are orangey-red, creating an attractive feature before they open yellow.

Mahonia are easy to grow and cope with most aspects but prefer shade. Most are hardy in the UK but M. lomariifolia AGM is only found in sheltered spots in the south and west. They like fertile, neutral to slightly acidic soil. They are inclined to go chlorotic in limey soil. People become concerned when older plants lose their leaves at the bottom, but this is natural. To keep specimens from getting too big or leggy, cut out a third of the stems each spring.

The biggest problem for Mahonia is the late spring frosts. New growth, particularly of M. x media varieties, can get frosted. It can be cut out, but sometimes it causes areas of stunted growth. M. aquifolium is inclined to get mildew if in very dry conditions.

Mahonia are very effective as part of an evergreen shrub border, alongside other winter-flowering shrubs such as Chimonanthus and Daphne, and structural plants including Fatsia and holly. They make a good backdrop for winter flowers such as snowdrops or hellebores. They can also be used as part of tropical planting schemes and young plants of M. x media 'Wintersun' or 'Charity' make excellent patio plants.

WHAT THE SPECIALISTS SAY

Joanne McCullock, nursery manager, Larch Cottage Nurseries, Cumbria "Mahonia are easy to grow. They are evergreen, have winter/spring flowers and are also excellent for shady or part-shady sites. One of the most popular varieties we stock is M. 'Charity'. It's an evergreen, multi-stemmed upright shrub, with ruffs of long, glossy pinnate foliage. It has drooping racemes of fragrant yellow flowers between November and February.

"I also recommend the rarer M. trifoliolata var. glauca. It has glaucous blue leaves and yellow flowers in the spring, followed by redcurrant-like berries. But my favourites are two newer varieties: M. x wagneri 'Sunset' and M. aquifolium 'Orange Flame'. Both have new growth that is orange and red, which then matures into green."

Matthew Tanton Brown, plant centre manager, The Place for Plants, Suffolk "For the landscaper, M. aquifolium is probably the toughest and the most drought-tolerant. M. japonica Bealei Group are also excellent, tough landscape plants.

"For gardeners, the most popular forms are the traditional favourites such as M. x media 'Charity' (tough and cold-tolerant), M. aquifolium 'Apollo' AGM, which is shade-tolerant and reasonably drought-tolerant, and M. x media 'Winter Sun' AGM that, like M. x media 'Charity', has good sulphur-coloured flowers and a good scent, but is also ideal in a north-facing spot.

"My favourites are M. nitens 'Cabaret', which is a newish form with wonderful orange-tinted flowers. It is also supposed to be shade-tolerant and reasonably good in drier spots. I also like M. x media 'Charity' for its scent and I find it does well in quite windy sites, too."

Derek Cox, consultant, Goscote Nurseries, Leicester "Mahonia comes in all sizes. Some are very good for ground cover or understorey planting in the border. For example, M. aquifolium 'Apollo' AGM or 'Smaragd'. They are both evergreen, with masses of yellow flowers in spring. I love how popular their blue-black berries are with birds.

"For specimen planting, the M. x media varieties are best. 'Wintersun' is outstanding and my favourite. It has large, ornamental leaves and upright spires of fragrant yellow flowers, from October to late December. Young plants of this variety, as well as the popular variety 'Charity', are also good in containers."

Steve Lampitt, grower, Ashwood Nurseries, West Midlands "There is a new variety, 'Cabaret', which has reddish-purple tips. It also has a fine leaf. For a different leaf shape there is M. x wagneri 'Pinnacle', with a more elongated leaf, and M. lomariifolia AGM, which has many leaflets.

"The standard variety M. x media 'Charity' flowers well and becomes a decent size. A good ground-covering type is the dwarf variety M. aquifolium 'Sioux'. It's similar to 'Apollo' AGM.

"The key to Mahonia is to prune them once they've flowered to keep them compact. They don't need much care and attention, but like a dappled shady spot."

SPECIES AND CULTIVARS

- M. aquifolium is a small shrub widely used as ground cover or low hedging. The glossy green, pinnate leaves sometimes turn red in the winter. It has rich yellow flowers in spring followed by blue-black berries. Height: 1.5m. Spread: 2m.

- M. aquifolium 'Apollo' AGM (H4) is a low-growing, dense variety, that spreads freely. Its leaves are deep green with red stalks, turning an opulent shade of bronze-red in winter. In early spring it bears bright-yellow flowers in large dense clusters followed by dark berries.

- M. aquifolium 'Atropurpurea' has foliage that turns a stunning red-purple in autumn. Height: 1.5m. Spread: 2m.

- M. aquifolium 'Green Ripple' bears wavy-edged leaves that are pale green, turning deep glossy green in summer.

- M. aquifolium 'Orange Flame' has new growth that is orange and red then matures into green.

- M. aquifolium 'Smaragd' is similar to M. 'Apollo' but more compact, has larger flower clusters and lovely bronze, juvenile leaves. Height: up to 1m.

- M. 'Bokrafoot' (PBR) is a very compact M. repens hybrid, reaching just 60cm. It is known for its immunity to powdery mildew and rust.

- M. gracilipes is an attractive small and slow-growing type with eye-catching purple-red flowers with creamy yellow centres in late summer or autumn. It has long, graceful leaves, which are white on the underside. Height 1.5m. Spread: 2m.

- M. japonica AGM (H4) is a popular reliable species. Its foliage turns rich red in winter, followed by beautiful, fragrant lemon-yellow flowers. Height: 2m. Spread: 3m.

- M. lomariifolia AGM (H4) is a tall, upright shrub with elegant, dark-green foliage made up of many deeply serrated leaflets. Rich yellow, scented flowers are produced from November to February. It is rather tender so needs a sheltered spot in milder counties. Height: 3m.

- M. x media 'Buckland' AGM (H4) is noted for its long flower racemes, up to 45cm, that begin blooming in late autumn and last through the depths of winter. Height: 2.5m.

- M. x media 'Charity' forms a strong architectural shrub that is popular for its sweetly-scented flowers, appearing from October. It grows to 2m.

- M. x media 'Lionel Fortescue' AGM (H4) bears masses of bright-yellow winter flowers in strikingly upright racemes.

- M. x media 'Winter Sun' AGM (H4) is a popular form of Mahonia for its excellent flower fragrance. The yellow flowers are borne on large, erect racemes in mid winter, followed by small, ornamental purple berries.

- M. nervosa is a low-spreading variety that is a good ground cover option. Its foliage takes on a purple tinge in the winter. Height: around 60cm.

- M. nitens 'Cabaret' (PBR) is a compact shrub that produces bright orange-red flower buds that open into elegant racemes of yellow flowers, lasting from August through to November. Height: 1m. Spread: 80cm.

- M. repens, a creeping Mahonia, reaches just 30cm in height. Its suckering habit makes it a good choice for ground cover.

- M. x wagneri 'Pinnacle' AGM (H4) is a vigorous, upright form with bright-green leaves. It has showy clusters of bright-yellow flowers in March.

- M. x wagneri 'Undulata' produces dark-green, wavy-edged leaves that turn purple in winter. In spring it produces deep-yellow flowers, followed by blue-black berries. Height: 2.5m.


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