Frost

I have been growing bonsai in the same area of Sydney for the past 7 years, but I’ve never seen my trees to be exposed to sub-zero temperatures. This morning I found frost on some of the leaves and ice in the drip trays. The lowest night temperature for my area was reported to be 6°C and at the time of taking the photos shown above the temperature was reported to be 18°C. A disparity of 20 degrees! No wonder everybody thinks there is global warming.