How to Grow Mahonia

Mahonia is a winter flowering, evergreen shrub.

Mahonia can get a bad press because they are sometimes in landscaping arrangements around supermarkets and roundabouts.  Seems harsh, as Mahonia is an easy to grow shrub, with winter colour,and berries for the wildlife. On mass, their bright yellow flowers are attractive and some varieties, see below, have scented flowers.

Mahonia is mostly trouble free shrub, which makes them easy to grow and labelled a green wheelbarrow shrub. They look good in a border mixed in with other evergreen shrubs and have the advantage of being fast growing. Mahonia is often planted on a perimeter to make 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.

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 Mahonia is upright and tall, but in fact there are many varieties with of different sizes, although all tend to be fast growing. 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. The upright varieties are the most common, but there are also a low growing varieties,   Mahonia repens, which grows up to 30cms, illustrated in the image below right and can be used 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 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.

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 look good under planted 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.

Problem Mahonia and How to Prune Mahonia

The most common problem is that a mature Mahonia can get leggy and become bare at the base with all the leaves and flowers in the top growth.  Mahonia can be left unpruned,  but if the shrub has become leggy and 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 becoming bare. 

It is easy to resolve the problem of leggy Mahonia as fortunately Mahonia belong to the group of evergreen shrubs which will respond well if they are hard pruned. You can cut down hard Mahonia, Choiysa and Rhododendron and whilst they will look a bit sorry when first pruned within the season they will start to sprout new growth and recover.

Mahonia with berries and Mahonia repens 'Rotundifolia'

Last updated 29.01.2021