I got 2 boxwood from Lowes last night, I popped them out of the 1 gallon pot and the roots were everywhere, and I mean super rootbound. I chopped about half of the roots and dirt from the bottom on both and put them in 5 gallon decorative pots to stay outside all year around. don't know if I will bonsai them in years to come or just keep them containered. Was it too late to repot and chop some root. There is still at least 6 inches of rootball on bottom after chopping.
They should be fine they may turn a little brown but just make sure you water them regularly. If I were you I would give them some sort of plant food as long as its not a chemical. Something maybe like 10.10.10 or 14.14.14 but don't do it yet I would make sure. Just losen the roots a little with your hands so it can get a good start of growth.
Thank you for the quick reply. I will keep an eye on it. They are pretty hardy plants. Thanks, by the way, Lowes has great pre-bonsai starters in gallon containers for 6.95! Thicker trunks than any bonsai you'll overpay for online!!!
I probably would have avoided root pruning right now as there really was no urgency. You could have slipped them from their pots and buried them in your landscape somewhere and they would have over wintered nicely. Your root pruning now may encourage them to produce new, tender roots going into winter, so make sure to provide a little extra protection this year.
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