As midsummer approaches, it's the perfect time for Monty to place succulents outside at Longmeadow, as well as planting out dahlias and tender vegetables.Carol Klein visits Trebah Garden in Cornwall, where she finds plants which can add early summer pazazz to our borders. Nick Bailey is at RHS Wisley to look at a variety of shrubs that can be used as alternatives to traditional box hedging.We travel to the seaside in Kent to meet a group of gardeners who have transformed an unloved public space, and in Wales, we find a garden packed with unusual and prehistoric plants.