Hedges, houseplants and houseleeks – and can you grow your own wasabi peas?

What type of hedge is best for trapping pollution? Which hedging plants help mitigate flooding risks? Can you grow roses and clematis together to make a flowering hedge? We went to a recent 'Hedging Your Bets' event at RHS Garden Wisley to find out more. Plus the Gardening Advice team gathers to answer queries on houseplants for a shady bathroom, growing houseleeks and aeoniums, the secrets of making great compost – and whether you can grow your own wasabi peas?!