Planting Trees in Cornwall Plant one tree? What difference would that make when it’s estimated we’d need 22 trees to offset a return ticket from London to New York? But what if we could grow that number by bringing people together? Our mission is to bring people together in a joint effort to plant ten million trees in Britain. Regrowing our long disappeared Celtic rainforests to help fight climate change and encourage our diverse wildlife and support delicate ecosystems for future generations.