I assume all trees buried outside have their roots frozen. My burning bush has done just fine in previous years it was buried. The ideal situation I thought being they freeze and stay that way til spring. I mean, non-bonsai burning bushes survive just fine in this area, even small/new ones.
The ones you left outside unburied, did u leave them in their pot, without further mulching or protection?
Thanks.
You are correct. Temperate trees, potted or planted in the ground....maples- tridents, Japanese, etc, junipers, burning bush, etc., all can easily deal with sub freezing weather. Yes, they can have the soil in their pots freeze, and it can stay frozen for months on end without any detrimental side effects. Freeze-thawing could potentially be an issue (in my experience a minimal one), but is easily avoided by placing the trees in pots in an area out of direct sunshine (and wind) and mulching the pots with wood chips. Water them in, let them freeze in December and leave them alone until the mulch thaws next March. I've heard tridents are sensitive to frozen roots, but I've had my tridents freeze solid and they stayed that way in my garage in zone 6 MA from December until April with no issues at all.
Fwiw, when I hear about trees that are winter hardy in your zone that die over the winter, I would look back to the previous growing season. Trees that are weakened due to summer heat or drought stress, insect or fungal disease, or poor horticultural technique (read that as bad soil or watering issues, not enough light, etc) are the ones that are most likely to succumb during winter dormancy, and it generally has nothing to do with how cold they are.
PS I had a burning bush potted and being trained for several years before moving to GA. They are hardy to usda zone 4, I believe. Let it freeze solid, keep it out of winter wind and sun, mulch the rootzone to prevent large temp swings, and it will be fine.
