On the busiest gardening weekend of the year, Monty Don has plenty of ideas and inspiration from planting summer bulbs to sowing perennials. New projects are on his mind as he begins to mark out a brand new area at Longmeadow. Meanwhile, Carol Klein profiles the bravest and most colourful of spring flowering plants when she delves into the botany of the hellebore. The programme also pays a visit to Sheffield to view a garden crammed full of colour and new ideas. Includes Weather.