When people tell me they want more colour in their garden, I don't immediately think about flowers. That might sound rather strange coming from a gardener, but over the years I've learnt that colour is only one part of what makes a border enjoyable to look at. Some of the most memorable gardens I've visited haven't been full of flowers every month of the year. Instead, they've offered something different as the seasons changed. Fresh green leaves in spring, bold summer blooms