(please not I am also posting this in the Hydrangea forum as I'm not sure which forum is best for getting an answer. I hope that's ok)

So like every new gardener I made a rookie mistake. I got too excited about planting and did not take enough time to properly amend/prepare my soil. (bows head in shame)

As a result, I have 4 hydrangeas that suffered from my overeagerness, but have somehow managed to dwindle along for a year now. Now before they completely die, I've decided to swallow my pride and ask for help.

Here are the issues:
*poor soil
*I didn't remove the container mix before planting
*planted too closely to the foundation
*planted on the west side (get only hot afternoon sun)
*I have no good soil even in a good location to transplant them to at the time being.

My Plan of Action:
*Remove old soil
*Root prune
*Move to containers using Gritty Mix

My Questions:
*When should I make the move to the containers?
*How much should I root prune? Is 1/3 ok?
*How large should the containers be? (please respond in inches not gallons because I really have no idea what that means)
*Should I put them on the east side immediately or keep them in shade for a while?

Please chime in with ANY and ALL advice. I know I've made horrible mistakes but I really hope to avoid them from now on and I'm very eager to learn! Thanks!!