The Breckland heaths are renowned for early season frosts. In 1958 I was working for the Forestry Commission and we had a very sharp frost one morning. One of our people had 1/2 acre of potatoes well up. Another from the same village, laughing, said "How're yer taters going on now, Freddie" and the reply was "my taters are OK, I was up at 4 o'clock, watering the frost off". It saved the crop, but must be done before the sun strikes the leaves.