transplant?

Yesterday I asked about creating better drainage in clay soils, and I got quite a few suggestions (although I'm not yet certain what I'll do). Today I have another problem that I'd like some opinions on: transplanting.

This isn't your typical "dig it up and move it" transplant though. In fact, it doesn't really look like a transplanting at all -- but that's what it is.

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You see, I've had this little Austrian pine for a few years now:

My strategy with trees is usually this: buy small, grow in pots for a few years, save lots of money. That's what I did with this tree, as it was only $6 or something like that when I bought it. It's been doing nicely in the pot, but I haven't moved it for over a year, and I know what that means.

It means that this tree has rooted itself into the ground. I don't even need to try and lift the pot to know this. The fact that it's getting larger than it seems like it should in such a small pot is another clue.

So I know that when I move this I'm going to be severing a good portion of the tree's root system, which leads me to my main question:

When should I do this?

Is now the right time? Should I wait until spring? Late winter? Should I have done this in the fall?

Also: will this do irreparable harm to the tree? I've done this before with deciduous trees, but not with evergreen conifers.

Another approach would be to break the pot then dig up a larger root ball. I really don't want to do that, as this is a nice, frost-proof pot. Is it worth more to me than the life of the tree though?

If you have any experience with transplanting pines please leave your advice in the comments, but I'd love to hear what everybody thinks too -- regardless of experience.

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