Spring is nearly upon us and Gardeners' World is back with a new series. As usual, Monty Don is at Longmeadow, reviewing the effects the winter weather has had on his garden. Carol Klein visits a Welsh hillside garden and delves into the botany of bulbs with a couple who have used a scientific approach to plant their garden with the earliest of spring flowers. It is the perfect time of year to plant trees and Joe Swift gives us his guide to choosing the best ones for our gardens. And there is a glimmer of hope for gardeners who have had to cope with copious amounts of rainfall this year when we visit a garden which, last year, was brought back from the brink of destruction with spectacular results.