Royal Horticultural Society

Cultivation notes

Box is tolerant of a wide range of soil types, provided there is adequate drainage and it does not dry out completely. A reliably moist soil is especially important if growing in full sun, otherwise the foliage may scorch. Box will tolerate deep shade and is ideal for planting beneath taller trees.

Planting in the garden

On poorer soils, spread organic matter, such as well-rotted manure or garden compost, 5cm(2 ins) deep over the prepared area and fork in.

Plant common box, Buxus sempervirens about 30 - 40cm (12 – 16in) apart. More compact cultivars, such as ‘Suffruticosa’ and Buxus microphylla, can be planted 10 - 15cm (4 – 6in) apart.

Do not allow young plants to dry out. Check regularly and water to keep the soil moist. Once established, apply a general-purpose fertiliser at 70g per square metre (2oz per square yard) in spring and mulch to a depth of 5cm (2ins).

If well cared for, small plants should form a reasonable hedge or parterre within three to five years.

Planting in containers

Box can be successfully grown in containers, and is often clipped into formal topiary shapes.

Select a container at least 45cm (18in) in diameter and use a loam-based compost, such as John Innes No 3. Make sure plants never dry out, even in winter.

Apply a liquid feed during summer.  Topdress established container-grown plants in spring with fresh compost and a little slow-release fertiliser, such as Vitax Q4 or blood, fish and bone.

Links

Mulches and mulching
Plant nutrition
Container maintenance
Hedge planting

Pruning and training

Cut back young hedge plants and topiary by up to one-third in May to encourage bushy growth. Further trimming can be carried out between May and August, as required.

Trim mature hedges and topiary twice during the summer, with the first cut in about late May and the final cut before the end of August.

Old, neglected plants usually respond well to hard pruning in late spring (May) and can be cut back to within 15-30cm (6-12in) of the ground.

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Renovation of old shrubs
Hedge pruning

Propagation

Box can be easily propagated by taking semi-ripe cuttings. Cuttings will root in the open ground if the soil is moist and there is some shade. More reliable results come from placing cuttings in a cold frame or similar environment. A heated propagator will speed the rooting process, and you should see roots after eight weeks, as opposed to up to eight months without heat.

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Semi-ripe cuttings

Cultivar Selection

• For larger hedges, Buxus sempervirens AGM is a popular choice.
• A much slower growing cultivar suitable for parterres and small hedges is B. sempervirens ‘Suffruticosa’ AGM.
• B. microphylla is a naturally compact form of box that needs no clipping to form a shrub.
• For variation in colour, grow the yellow-spotted B. sempervirens ‘Latifolia Maculata’ AGM or the cream-edged B. sempervirens ‘Elegantissima’ AGM.

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Buxus 'Rosmarinifolia'

Problems

Excessive sunlight can cause discoloration and sun-scald to leaves. General bronzing of the foliage is also due to environmental stress usually following hot, dry spells in summer, although a contributing factor may be root damage due to winter waterlogging.

Over winter, leaf tips and margins commonly yellow due to low temperatures. Leaf discoloration will tend to be more common in exposed sites. Young growth in spring can also get caught by frost, turning them pale brown and often papery-looking. An application of fertiliser in spring to encourage fresh new growth, along with clipping, usually rectifies these problems.

General yellowing of foliage may be symptomatic of waterlogging, especially on heavy clay soils. Roots subjected to waterlogging are usually a blue-black colour in cross section and fall apart when teased out. Damaged roots should be removed, top growth trimmed back and the box replanted.

Box may sometimes suffer from the following problems:

Links

Box blight
Box sucker
Plant establishment problems
Red Spider Mite
Scale insects
Waterlogging