Dav4

I have experience with yews, both as landscape trees and as bonsai. They are hardy evergreen conifers that are shade tolerant, meaning they will grow ok in less then direct light. In fact, when dormant, yews and other evergreens need little to no light. However, that doesn't mean they don't need alot of light when actively growing. In many instances, trees that have been recently collected or root pruned need to be kept out of direct sun for a few weeks as their compromised root system needs to repair itself. Generally, trees are collected or root pruned in spring time when they are awakening from dormancy and are metabolically ready to deal with these insults. The problem with your situation is that there will be inadequate light for your tree, shade tolerant as it is, to repair itself and grow properly.

The goal with any potted tree in winter is to keep it dormant as long as possible until appropriate weather conditions allow it to awaken and grow normally. This will not happen if the tree stays in the attic. It stands a better chance outside, out of the direct rays of the sun, out of the wind, with its pot mulched to protect its roots.

Dave

ps I just read your post. It is the best you can do...good luck.