"Did you know it's been raining"? asked the cheery staff at Canonbury station when I asked to borrow their watering can, to water all the plants at the station, supplied by Energy Garden. No worries, I thought. You need to apply enough water to saturate the soil that holds this root system. Roots need air to function, and rain can temporarily drive all the air out of the ground. And anyway, by the time I went down to water the plants, the sun had come out.