Yesterday the Toronto gardeners and sisters Helen and Sarah Battersby, reminded me that hydrangeas like a lot of water.  "Hydra" is right there in its name so it shouldn't be too hard to remember.  Fortunately, my 'Mothlight' hydrangea purchased a number of years ago from Nasami Farm (before it belonged to the New England Wildflower Society )  was planted where I do some watering. The bush itself got much bigger than I expected! I bought 'Mothlight' because I…