Peter Gibbs is at the Sheffield Botanical Gardens for a correspondence edition. Bob Flowerdew, Anne Swithinbank and Matt Biggs are on hand to answer questions sent in by listeners via post, email and social media. This week, the panellists take shelter from the rain while offering suggestions for plants in a boggy garden, advising on how to re-pot cacti and considering whether deciduous or evergreen trees are best for CO2 absorption. They also discuss how to prune by touch for a blind listener. In between the questions, the team wander the Sheffield Botanical Gardens, led by Ian Turner. Producer: Dan Cocker Assistant Producer: Rosie Merotra A Somethin' Else production for BBC Radio 4