Helen Mark is invited to Lisbane County Down where she discovers the work that goes into preparing a garden for public visitors through the National Garden Scheme, and the challenges of gardening on a hill with Olwen Sheridan. With secateurs in hand, Helen helps Joy Caskie on a spring tidy-up, cutting back, moving plants and trimming edges and getting some ideas for her own to-do list. And after a midlife career change, Gary Hegarty swapped designing newspapers for sensory gardens. Here he shows Helen the benefits of these special spaces. Ann FitzSimons joins Helen in studio. Email the programme at gardenerscorner@bbc.co.uk