I have three very young acer palmatum japanese maple seedlings ranging from about 5-10 inches tall. They are currently in 2 gallon pots and I live near Pittsburgh, Pennsylvania, where we receive fairly cold and snowy winters.
Right now the plants are in our outer greenhouse which never really drops below 40 deg. F in the winter and still receives a fair amount of sunlight. It's now almost Christmas and the young trees are still retaining about 40% of their leaves and I am worried that the environment they're in is not cold enough to trigger their winter dormancy stage. I was reading that they are fairly hardy, but my concern now is that they are not winterized and bringing them outside now could kill them. Our outside temps range from about 10 deg. F to 35 deg F. I have a shed which receives some light and would break the wind and snow while providing a colder, dimmer environment.
I guess my questions are these: Should I begin hardening the seedlings by bringing them outside for a portion of each day, with the aim of getting them into the outer shed until spring arrives? I've read that mulching the soil and potentially wrapping the trees can help them through the winter. I'm just not sure what to do and I''d hate to see the beautiful potential of these trees cut short. Thanks so much for your input!