A special programme from the first big flower show of the season – the RHS Malvern Spring Festival. Rachel de Thame and Nick Bailey explore show gardens packed full of ideas and discover the newest varieties of plants and flowers that are hot off the potting bench.There are the herb specialists from Gloucestershire who believe that edibles are just as important as ornamentals in the garden, and a nursery famed for its foxgloves that also has an impressive collection of tree peonies.Toby Buckland celebrates spring colour at Aberglasney Gardens in Carmarthenshire, and Arit Anderson spends the day with a charity group that gives horticultural work experience to vulnerable people and those with learning difficulties.