The gardening advisors gather to solve queries on what you can prune now, whether you can plant trees in winter and how to protect bay trees from cold weather. Resident wildlife expert Helen Bostock meets Adrian Thomas from the RSPB to find out which birds come to Britain in winter and how gardeners can encourage our feathered friends. Plus a look at the incredible transformation happening to Wisley's iconic Laboratory building, and the science team discusses two emerging threats to a traditional Christmas favourite, the chestnut.