Along the lines of what Lucky was saying, I think there's probably an important distinction between the freezing temperature of pure water and "actual freezing." I'm not sure what "actual freezing" would mean for scions, but I assume there are parallels to things like harvested fruit or meat. I believe the large-scale nitrogen-filled storage facilities for apples (and I think pears, too) are kept just below 32 degrees, because the sugars in fruit prevent apples, etc. from actually freezing until temperatures get 2 or 3 - I'm just throwing out a guess here - degrees colder. I know meat is similar, even though sugars aren't at play. If you put ice bottles in a cooler with hard frozen meat, you'll notice the meat will thaw before the ice will. The freezing temperature of meat I think is around 28 degrees. So if you wanted to optimize the storage life of meat WITHOUT freezing it, you'd keep it at 29 degrees. There must be something similar with scions. I also wonder why scions couldn't be stored at temperatures as cold as they'll withstand on the tree. In other words, if a piece of a tree is fully hardy to -10F on the tree, what changes when you cut it off? I'm assuming something must be different. Does it just have to do with moisture migration (as with freezer burn)? Or are cell walls getting ruptured as when you freeze strawberries and thaw them and their texture is nothing like it was fresh? Harvestman, to your concerns about the fluctuations that a thermostatic control like that would allow, I don't think it would be hard to buffer those fluctuations to effectively make them disappear. One idea I'd have for a buffer would be a contained salt solution (obviously you wouldn't want any salt contacting the scions) that would freeze-thaw at the desired temperature -- there are charts to easily figure out how much salt will drop the freezing temperature of how much water how far -- but sand or sawdust or anything would work so long as the fluctuations in the temperature around the thermostat probe didn't penetrate the insulating/buffering material faster than the on-off cycles.

Check the roots for vole damage. Pine voles can girdle roots without being apparent above ground.

Wow. That's a buncha jars!

I freeze dutch apple pies before I bake them. Is dutch apple topping the same as streusel? Every fall I make about a dozen peach pies and apple pies for the holidays, freeze and bake when needed. I wrap them in non-stick aluminum foil and freeze in freezer ziploc bags. Unwrap, place frozen on lined cookie sheet at preheated 375 for 15 minutes, then reduce to 325 until they bubble over a bit. Usually about an hour or so. (But my oven runs hot.) You really can't tell the difference between fresh baked and frozen baked. You have a lucky plumber!!