Gardening's best-kept secrets

This week we're unwrapping lots of gardening goodness, from expert seasonal advice and untold stories to wildlife tips. Nursery owner and plantswoman Claire Austin shares inside information on what the people who produce plants for our gardens are doing at this time of year (it's much more than you might think!); Zehra Zaidi tells the little-known story of John Ystumllyn, an 18th century African gardener in North Wales and Helen Bostock heads into the undergrowth to share tips on how to help hedgehogs in your garden.