Every spring, the experts who are growing plants for the RHS Chelsea Flower Show – whether for the Great Pavilion or the show gardens – have either warm or cold weather, cold nights or late frosts to contend with. And this year is no exception – the unseasonably warm spring, which has already seen roses in full bloom in the south, is creating a challenge for Chelsea growers. The good weather has brought plants on too early. Paul Seaborne, Pelham Plants Paul Seaborne is coordinator of this year's Plant Fairs Roadshow within the Great Pavilion and owner of Pelham Plants. "I really wanted to include a vibrant orange Geum 'Dark and Stormy, and was looking forward to seeing that with the dark purples on the display, but it's all in bloom now," he says. "I'm also looking at Cirsium 'Trevor's Blue Wonder', a classic for Chelsea, with a really vibrant purplish-blue flower.…