Box, Buxus sempervirens is one of the most essential elements of the garden. Formal gardens depend upon compact, shaped evergreens to provide their regular structure. Low box hedges, perfectly clipped, have been used for centuries to create the knot garden and the parterre. Informal gardens need solid evergreens as focal points and exclamation marks in their otherwise unfocussed planting. We use small, compact evergreen shrubs, such as box at the corners of beds, at intervals along borders, by doorways, alongside paths and steps and in pots and containers. Traditionally box is used to fulfil all these roles: its small leaves and dense bushy habit mean it is easily clipped and shaped to fulfil whatever small evergreen role the gardener demands of it. It is also generally tolerant, growing on any soil type in sun or shade.
So why consider alternatives? In some areas box blight, a fungal disease has wreaked havoc with box hedges and topiary. Appearing as a brown discolouration of the foliage which then turns to parchment and dies back into the shrub it is very disfiguring and can be fatal. With care and chemical control box can recover, but it takes time. Nutrient deficiency, usually lack of potash is often mistaken for box blight. This appears as bronzing of the foliage in winter; the whole plant looks orange. This is easily cured with a dose of high potash fertiliser. Late frosts can also cause damage to new growth in late spring. The new shoots are knocked back and the damaged leaves turn papery as they dry out. The plant soon grows through, but not before the gardener becomes concerned that it’s something more serious.
Can box blight be prevented? Healthy box hedges growing in top conditions will be less prone to the disease. In dry weather watering helps, but feeding is essential. A high potash fertiliser, such as rose food, helps to harden the foliage and promote strong, not soft growth which can be more susceptible. Ideally box should not be clipped before early summer; cutting too early can produce soft new growth which is more susceptible.
So what are the alternatives? In fact there are plenty, and many that will provide different foliage effects while still fulfilling the role of box hedges and box shapes.
Ilex crenata ‘Convexa’ is easily mistaken for a variety of box. It has small shining dark green convex leaves of very rounded appearance. It is slow growing, dense and bushy, ideal for the small garden, in gravel or scree, in a narrow border, or alongside steps or a patio. It makes a superb slow hedge and does not suffer from the bronzing of the foliage that often effects box, especially in winter. (See pp.00)
In milder areas, town and costal gardens Pittosporum tobira ‘Nanum’ is an excellent evergreen forming a low dome-shaped shrub up to 80cm in height. The shining dark green leaves are carried in rosettes giving a most attractive, regular appearance. Fragrant creamy-white flowers appear in summer. This is an excellent choice for pots on a sunny patio and a good alternative to box in a Mediterranean scheme.
Pittosporum tenuifolium ‘Golf Ball’ is a personal favourite: a compact rounded shrub with small, shining bright green leaves and black stems. It clips well and is surprisingly hardy for a shrub that looks light and delicate.
The evergreen euonymus are among the most versatile and durable shrubs. The small leaved varieties of Euonymus japonicus are excellent compact evergreens that thrive on any soil in sun or shade. They are excellent subjects for pots and remain compact, their upright stems crowded with leaves requiring very little in the way of trimming and shaping. If you are looking for a plant with structure but without the formality of clipped box then look no further. Euonymus japonicus ‘Microphyllus Variegatus’ has dark green leaves edges with white, Euonymus japonicus ‘Microphyllus Pulchellus’ has dark green leaves suffused with gold. In both cases, because the leaves are so small and tightly packed on the stems the variegation is very subtle.
Where a narrow, columnar dwarf shrub is required try Euonymus japonicus ‘Green Rocket’. This has shining emerald green leaves on vertical stems. It is ideal for small gardens and narrow borders and looks particularly attractive in tall slender pots. It grows to around 60cm in height, after which it tends to open up. To keep it vertical cut some of the stems back occasionally to near ground level.
If you want a dwarf evergreen with more colour, Photinia x fraseri ‘Little Red Robin’ takes some beating. This only grows to around 1 metre in height, but responds to regular light pruning by producing a flush of deep scarlet new shoots. The leaves are smaller than its larger cousin and darker green. It is an excellent plant when it comes to maintaining colour throughout the year, as well as providing evergreen structure.
For larger leaves and compact rounded form choose Viburnum davidii. This plant has perhaps the most impressive plain dark green leaves in the garden; elegantly oval, pointed, with red leaf stalks and deep veins. It grows to around 90cm in height, but is often less than this and can be pruned if necessary. Few plants are more versatile. It is a brilliant choice for pots in shade, grows well under trees, makes a spectacular low hedge and thrives on any well-drained soil. Sadly it is seen as a boring landscape shrub rather than an aristocratic garden plant – a big mistake!
I’m sure many of you will be saying “He hasn’t mentioned hebes!”. Well, I would love your suggestions of other shrubs you’ve used instead of box. Also it will be really useful for other readers if you have tips on growing box and keeping it healthy; do share them!
Suggestions from Elspeth:
For fun I have seen smaller displays in pots designed to give a miniature toy-town box effect, Selaginella Apoda, grown here with real Buxus sempervirens ‘box balls’ in the background