That really depends on the plant and how hardy it is. I have several groves and single Japanese Larch that go on the ground, mulched in with leaves. Some of the other hardy stuff can be Wintered the same way.
I also have a cold frame for some of the evergreens that I feel need some protection, and a warm but unheated shed (against the house) and an unheated garage, so I have many options. I don't think there is much difference between enclosed bottoms and open once the plants go dormant. They can either tolerate the cold or they cannot.
Here in So. Jersey the temp. rarely gets much below 10Ã‚Â° and rarely stays in the teens for extended periods of time.
So in short I'd say that I use the normal amount of caution/common sense for over-wintering the open bottoms that I use for the others.
Basically, if you soak your substrate just before a hard freeze you're looking for trouble no matter what the make up of your pot.
"As the twig is bent, so the tree inclines"
"I rarely agree with most of what I say........." -
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