I count myself lucky having a very small garden in London. It won’t win any horticultural prizes and “No Mow May” is the perfect excuse for benign neglect. But it has grass, the shade of an old apple tree and a water feature, and, in this heatwave, it’s a sanctuary. Most people have the same instincts, heading for shaded parks. In heat like this, we all want grass and trees. But I keep getting lea

