This morning I looked at the 10 day weather forecast, and the coldest overnight temperature predicted is 5°C (41°F) on the 17th and 18th of May. The temptation is there to start lifting the plants from the ground in the polytunnel and start planting them outdoors. However, the winds on the 24th are from the North East, and I only have to see the words "north" & "wind" to get cautious. Our prevailing winds are from the south west, bringing warm air from the gulf steam. To the north-east lies Norway, Russia and other cold places, brrr!
We have had frosts at the end of May in the past, so, reluctantly we will go on the side of caution, and give it another day or two before deciding.
I must comment that I have never seen the collection looking so healthy at this time of the year, and we are hoping for a great year of Canna growing after the bad years we have had.