May is normally when my garden starts to come into its own. I dust off the outdoor furniture, sit out and enjoy my collection of sub-tropical plants, from palm trees to yuccas. This year, however, I’m feeling as deflated as my enfeebled plants. My BBC weather colleagues and I often exchange stories about how our gardens are doing. Like mine, theirs have been nipped by all the sharp frosts we’ve had this spring. Meanwhile, people are stopping me in the street, asking when spring will finally arrive. And what have we done to deserve such cold, gloomy weather dragging on so long?