At the point when my bonsai collection was at it's largest, I was- 1) fully employed and worked 40-55 hours a week 2) married to someone who worked similar hours 3) had 2 school age children neck deep in school and extra-curriculars -4) the owner of a large house set on a nice but complicated plot of land, didn't have a greenhouse but had a large deck I could easily store things under and a 2 car garage full of crap, and 5) Lived in N GA where winters were relatively short/mild, but we could, in mid January, see temps fall into the single digits or have tridents, both in the landscape or in pots breaking dormancy, with the potential for future freezing weather into April. Without a doubt, there's an ideal time to re-pot a certain tree in a certain climate, but family life and late winter/early spring weather tend to complicate things, and bonsai was pretty low on the totem pole when it came to competing with work and family stuff. There were years when I might need to re-pot over 30 plants, and my collection definitely trended toward larger trees at that point. Those years, I might start re-potting maples in mid to late January... 6 weeks ahead of schedule... knowing I might not have time when the buds started to push. They'd end up on the garage floor, +/- bottom heat, and happily sit there for a 4-6 weeks before beginning to grow, and then the 2 step would begin... these received the most protection as they were most likely to break dormancy and were probably the most susceptible to freeze damage after root work and/or while breaking dormancy. Smaller pines and junipers would get re-potted as needed and left on the bench unless it was going to fall into the 20's F... into the garage they'd go. The real big, honking junipers would get placed under the deck, perhaps with some mulch, if freezes were forecast. Did they freeze solid once or twice under there... yep, though I suspect the soil really didn't freeze all the way through the pot.
Anyway, the point of this post is to point out that I never lost a tree to re-potting "early" (excluding those wimpy dwarf maples cultivars that truthfully all came from the same vendor and all met the same fate, making me wonder about their health when acquired, but I digress
). Ultimately, if you keep trees in climates where it freezes outside, you WILL be doing the bonsai 2-step whether you re-pot early or not, and the earlier the re-pot, the more 2-stepping to be done... unless you're lucky enough to have a green house or cold room with good supplemental lighting. I'm actually planning to start some re-pots next week as this coming March is gonna be a busy one for me... and I'm living in MI! Wish me luck!!
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