In the first of a four-part series of films from America's east coast, Stephen Lacey meets top US designer James Van Sweden, famous for his perennial prairie plantings.
Meanwhile, Joe Swift goes on the trail of the lupin in north Devon. Plus more tips and advice from Alan Titchmarsh.
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BBC Books: Gardeners' World: Practical Gardening Course by Geoff Hamilton, price £12.99, and Geoff Hamilton: a Man and His Garden by Gay Search and Tony Hamilton, price £7.99, both in paperback and available from retailers.
Alan Titchmarsh: page 39