Despite being advised to heel in trees or simply cover potted trees in mulch over winter, I did bring some potted trees indoors in a dark, cool (~50F), fairly dry (~30% relative humidity) basement. Sure enough they are leafing out before their outdoor counterparts and while nighttime temps still dip into <30F freezing temps.
What's the best path forward for these trees to survive and eventually acclimate to a planted place? I've had young trees seem to die off in the past only to burst back into life at some seemingly random point over summer, so maybe it's worth prioritizing their acclimation to the outdoor climate even if they lose a batch of leaves/buds from it.
The species in question are hazelnut, linden, black locust, and apple.
Some options I've considered:
Leave them in the garage til it's warmer, and if so, what kind of minimum temps are OK for them (does it need to be >32F or can they handle some frost)? If in the garage, should I water them or put them in a slightly brighter area? If bringing them outside, any precautions I should take, like covering the pots in mulch as I would've in autumn?