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How to Grow Mahonia
Mahonia is a winter flowering, evergreen shrub.
The inclusion of Mahonia in landscaping around supermarkets and roundabouts sometimes gives it a bad reputation. Seems harsh, as Mahonia is an easy to grow shrub, with winter colour, and berries for wildlife. On mass, their bright yellow flowers are attractive and some varieties, see below, have scented flowers.
Mahonia is mostly trouble free shrub, and labelled a green wheelbarrow shrub. They look good in a border mixed with other evergreen shrubs and have the advantage of being fast growing. Mahonia planted on a perimeter makes a good security hedge because of their very spiky thorns.
Mahonia is best in part sun/part shade but is shade tolerant. The winter flowers provide late winter /early spring nectar for any solitary bees emerging from hibernation. Mahonia has attractive evergreen foliage which looks a bit like holly leaves.
Planting a Mahonia is easy; soak the root ball in water for 20mins and dig a hole about twice the size of the plant. Place in centre so that the top of the plant in the pot is level with the soil; back fill with good peat free compost firm in and water again.
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Mahonia is tolerant of most conditions, fully hardy and a tough shrub. Ideal for planting in troublesome parts of the garden.
Which Mahonia to grow?
The most commonly grown type of Mahonia is upright and tall, but in fact there are many varieties with of different sizes, although all tend to be fast growing. There are a number of very attractive scented varieties. The group of Mahonia known as M. x media are all upright varieties and illustrated below above center and right is 'Charity' which has lovely yellow fragrant flowers. There is also a low growing variety, Mahonia repens, which grow up to 30cms, illustrated in the image below and can be planted as ground cover.
The most popular varieties grown in UK gardens are:
Mahonia x media which grows up to 5m high 4 m wide and flowers from late autumn to early winter; good varieties are 'Charity', 'Winter sun' and 'Lionel Fortescue' and all are scented and very hardy H4. These have large upright, yellow, scented flowers. 'Charity' can be grown in a north facing spot, which makes it a good shrub for a difficult growing area.
Mahonia fortunei smaller 1.2m high 1 m wide which flowers in the autumn
Mahonia aquifolium, known as the Oregon Grape, image left is a smaller compact variety, up to 1.5 metres, very hardy and is spring flowering in March and April followed by blue black berries.
Recently the RHS have awarded Garden Merit (AGM) to Mahonia x media Underway which reaches up to 3m and has large erect spikes of fragrant yellow flowers in the winter.
Mahonia japonica is also hardy to H4, a mid-sized shrub growing up to 2m and scented.
A recent introduction is a red flowering Mahonia called Mahonia nitens 'Cabaret' which flowers in late summer and autumn.
When growing Mahonia, you do not have to prune the shrub, but a light prune, from time to time after flowering, will trim the shrub into shape and remove any dead branches.
Mahonia is ideal for under planting with snow drops and Hellebores to provide a mixed winter border. Suitable companion shrubs would be Berberis if making a thorny hedge, or Rhododendron, Azalea and Viburnum if planting a mixed shrub border. Another good companion plant is Cornus alba Sibirica with strong red stems.
Mahonia 'Soft Caress' Chelsea plant of the year 2013
There is a spineless variety available which has a slender habit, petite growing to around 1 x 1.2. It is fully hardy and looks a little like mimosa and is called M. eurybracteata subs.ganpinensis ' Soft Caress' It is quite different to the traditional Mahonia, and is for sale on Suttons website. Ideal if you would like a compact shrub with winter colour.
How to prune Mahonia
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The most common problem when growing Mahonia is that they can get leggy at the base, with all the leaves and flowers in the top growth. Mahonia does not require pruning, but if the shrub has become bare, prune out the leggy branches after flowering, or hard prune the whole shrub. Some gardening advice suggests pruning out one third of the branches annually to prevent the shrub from becoming bare.
Mahonia belongs to the group of evergreen shrubs which will respond well if they are hard pruned. You can cut down or even coppice Mahonia.
It will look a bit sad and sorry when first pruned, but within the season, new growth will appear and the shrub will start to recover. This image shows something of the problem, although it's not the best example. I will continue to scan gardens for a scruffier Mahonia. I think it is constructive to show plants and shrubs at their best, and their worst, as both grow in our gardens.
If hard pruning is not what you want, alternatively, don't prune, plant to disguise the problem.
What to do about a leggy Mahonia
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Looking at this mahonia, we cannot tell if the base is leggy or not. The dense planting of smaller shrubs in front of the Mahonia can disguise the problem and it works well. A strategic hedge.
A compact, low-growing Euonymus, probably a Euonymus fortunei 'Silver Queen', softens the leggy base in the other image.
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Mahonia with berries and Mahonia repens 'Rotundifolia'
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