In the Beechgrove Garden, Jim and Carole take the fortieth anniversary celebrations to a whole new level as they unearth the harvest of ruby-coloured potatoes planted 13 weeks ago. George and Carole revamp the rhododendron border at Beechgrove, and they show how to 'air-layer' a big shrub, and how to lift the crown of a small tree to ease congestion in the border. Jim meets Dundee's community allotment officer Kate Treharne. Kate takes Jim to visit two vibrant community gardens which prove that gardening is good for us on every level.