We have had a couple of nights with a good frost (-3/-4C), so I thought it was about time to move some of the more vulnerable plants in to the Greenhouse. I have a small thermostat controlled heater in here that will keep the temperature just above freezing (3-5C).
Mainly some established trees that don't like too much cold, like trident maples, azalea and outdoor Chinese Elm, also my growing collection of mame and shohin sized trees in small pots and of course the cuttings that were rooted earlier this year.
Most of the Japanese White Pine and Junipers are now in the cold Greenhouse, mainly to protect them from excessive rainfall and cold winds. No heating in here and the greenhouse is well ventilated. The Pyracantha are in there to keep the birds from stripping the berries.
My Scots Pine seedlings and starter plants will stay out until the weather turns really bad and then they will join the Junipers in the cold greenhouse.