English, Korean, Japanese and Dutch Box can all turn an annoying orangey bronze colour in winter. This bronzing is a natural response of this genus to cold and bright winter sun (cold winds don’t help either). It is not uncommon after a series of frosts (cold nights, sunny days) to get calls to the nursery from distressed gardeners about their bronzy box. This is more common in younger plants, but can also happen in mature plants. The plants are still healthy and will put fresh new green foliage on in spring. However, if your aim is to prevent this happening in the first place:
• In autumn, sweeten the soil with dolomite lime and feed well with all purpose fertiliser.
• Try to shield young Box plants from severe winds and strong winter sun, a temporary wind break is helpful.
If despite your best efforts your young box hedge goes bronze – don’t despair. Feed well in early spring and good new growth will soon emerge and your box will once again be a brilliant green. As they mature, the problem is less likely to occur.