Thanks for the reply! I'm in zone 5a, and I'm fairly comfortable that the garage temperatures will be appropriate. I suppose my concerns are primarily due to my inexperience. Things like:

-Are there resources available that discuss the necessary dormancy times for various trees?

-Do trees need to warm up gradually as they leave dormancy, or can I simply bring them inside after their time requirements are met?

-Common beginner mistakes/causes of death during overwintering?

Any info is greatly appreciated!

Your trees belong outdoors for life... dormancy is not the only thing that matters, though it's difficult to isolate specific other factors that they respond to. Trying to keep them indoors except for winter is not going to work - never has for thousands of us who've wanted to do the same. Maybe if you had more 'plant' experience in general you'd understand - many people put their house plants out from May through Sept. and the difference in how they thrive there vs being inside is quite obvious... it's about the quality of rain water (acid or not :), about breezes that strengthen stems, a more encompassing sun not restricted to certain hours on one side on windowsills, etc. etc. You really need to decide - if you want bonsai indoors, then get tropicals and learn how to grow (as bonsai) indoors, tho' we put them out in summer too, but if you want native trees (or at least those that will grow in the ground where you are) then don't consider growing them inside... won't work, or if you manage to keep something alive for a season, you may not be happy with how it looks vs those allowed to live out where they belong.

Beginner mistakes - asking trees to do things normally unnatural for them in the wild, putting them into dormancy ahead of their time, taking them out of dormancy too early (for our own sakes) only to discover a last hard freeze kills new buds/leaves and therefore whole tree. It's one thing to give them sun from late Feb. onward (window in the garage?) but another to put small pots out in e.g. late Mar. or Apr. only to have them freeze up again.

If you're determined to try to grow oaks and K. coffee trees indoors, you're only setting yourself up for discouragement (about bonsai).

Thanks for the advice! Those beginner mistakes sound like things I might be prone to do.

I've been trying to give the trees a more "outdoorsy" experience by adding the light opposite the window, blowing a fan on them, and putting them outside a few days a week. I also have some permanently outdoors for the sake of comparison. This may be a case where I've got to do it wrong myself before I learn, but I'm committed to trying it.

Does anyone know where I might find dormancy requirements for various trees?

Blowing a fan on them only depletes needed humidity... but spritzing from a bottle or tray won't make up for nature.

Sun through a window even just 1' away is dull, dull, dull to a plant or tree, doesn't compare to dull outdoor light which is so much brighter to them.

But I see you're determined to do your thing... so Google what you want to know (if you're going to try the fridge you're asking for trouble there). Good luck playing God.

I'd mention that the fan is oscillating and that my screened windows are open nearly 24/7, but it seems your opinion is that my project is destined to fail.

I truly thank you for your experience and willingness to share advice, however discouraging. In a year or two I may figure out that you were right and that I wasted my time, but I figure it's worth a shot...

I just hate that your experiments are living (now). Why ask for advice if you aren't going to take it? I'll say it again... trying to keep them indoors except for winter is not going to work - never has for thousands of us who've wanted to do the same.

I will second moochinka's advise. You know the saying ' what does not kill you ...'. Very true for plants. I killed my first maple like that long time back. A few years back I forgot a potted maple sitting on top (pot half buried) in a pile of mulch outside and in spring it came back stronger than ever. In fact, I leave most of my hardy plants (in zone 6b) in my vege patch sort of buried in shredded leaves in fall. They do just fine.

I do have a bunch of tropicals that I bring indoors during winter - actually an unheated and attached porch/sunroom with supplemental HID lights, T5 fluorescents and what not. They mostly sulk till I get them out in May. Inside I have to fight aphids, mites, scales, etc and once outside they are mostly gone.

Thanks! I appreciate the input. For now they seem to be doing well - one of the oaks just threw out another set of leaves. I think outside in shredded leaves is going to be my overwintering strategy, too...

Shredded leaves don't work for a small ceramic pot in your winters... you need a different strategy, but for now you need a 'parenting' course because you obviously don't care about your trees. You're depriving them of what they need and you will kill them.

Yaaaaaaaawwwwnnnnn

Yep. Ceramic/Clay pots will crack from freeze/thaw. Plus, a one year seedling like yours will require better protection. Unheated shed/garage will be a better choice. Also remember that the gradual decrease in temperature and light better prepares the plant for the winter dormancy.

Thanks! Exactly the kind of info I'm looking for. The pots are plastic, not ceramic. Still, it seems wise to keep them somewhat sheltered for their first winter. Looks like I'm flip-flopping back towards keeping them in the garage. I've been looking around online but can't find much about required dormancy times. Does anyone have experience in this department?

Also, @ moochinka: left to their own devices, these trees would've been eaten before even germinating. If they defied the odds and did germinate, they would have been quickly killed by the lawnmower. It's a matter of philosophy to be sure, but if the trees could talk I'm sure they'd be more than happy with their current gig.