Have you ever heard of onions that can walk? David Maxwell finds out all about them from organic grower Klaus Laitenberger. April showers bring plenty of growth in the garden including to plants often considered weeds, but wild garlic and nettles can also provide a tasty lunch as David finds out when he pops in with Ann Fitzsimmons. Also on the programme, garden designer and BBC Gardeners’ World presenter Adam Frost on his new book and the ‘King of Trees’ Tony Kirkham opts for a Cherry as his tree for April. David will also be joined by Claire Woods and Brendan Little who will take on gardening questions live – gardenerscorner@bbc.co.uk