It's late December, we've had a cold snap, and now a lot of people are asking me what is wrong with their Box, in hedges and particularly those in pots - instead of being a healthy green colour, they are turning a nasty orangey-brown shade, as you can see in the photos.
Well, I can tell you, in the words of Douglas Adams: Don't Panic!
This is called bronzing, and it's a perfectly natural phenomenon: it's a reaction to stress, which is usually a combination of cold weather, wind scorch, drought and a little bit of hunger. Plants in pots are particularly susceptible to it, as they don't get the same access to water within the soil that a Box hedge does, and they likewise lack access to pretty much any nutrients other than the ones we choose to give them - if we remember!
Come spring, these plants will need some feed and some watering: liquid seaweed feed is the best thing, both as a soil drench and as a foliar feed - and all that means is that you water it generously from above, splashing it all over the foliage as well as around the base. If you have any comfrey, then a well-diluted liquid comfrey feed would give them a treat: and if you have neither of those to hand, well, good old Growmore (or any other general purpose plant feed) will do.
During next summer, give them a good thick mulch of organic matter, with a fistful of Fish, Blood & Bone (which sounds like a particularly distasteful new boy band) beforehand, and make sure that - if they are in pots - they are well watered.
For now, there's not much you can do to help them, as there is no point encouraging them to put on new leaves now, just as the cold weather moves in: any new growth will just be ruined by the frost, and they will have used up their resources for nothing. Better to just take some photos to remind you that next year, they'll need some regular feeding through the summer to reduce the chances of it happening again!