I bought an azalea for 4$ from nursery stock. the leaves were pretty yellow, and I knew it was sick . When i took it out of its pot the rootball was crazy thick, and it had obviously been in there way too long. I raked out the roots, took off a good chunk of the rootball, defoliated some of the really undesirable growth, re-potted it in a regular non-bonsai pot, and fertilized it. now the centers of the leaf clusters are sprouting tiny green healthy-looking leaves.

My question is: Being that it is winter in the pacific northwest, what is my course of action? Do I defoliate the yellow leaves to increase vigor, do i defoliate the new stuff to encourage back-budding (or is it too early for that)? How long do I wait for my tree to get healthy to get in to some more serious shaping?

I don't know much about azaleas but I see why you repotted it. It wasn't a bad choice. It's been pruned enough now. You should wait till spring to do some serious styling.
Did you liquid fertilize it? If you did, I congratulate you for burning your roots.
A photo would help to give more advice.

You can take the yellow leaves off but do not de foliate healthy leaves. You will not increase vigour, you will weaken. The tree is already weak, and needs to recover. Stop the fertiliser. You re potted at completely the wrong time of year for Azaleas,, the loss of leaves was probably natural. Mine are losing some leaves right now.

Leave it alone. You have done a lot, at absolutely the wrong time of year.

Yellowing of leaves means that the plant is withdrawing nutrients from the leaves. Let the plant decide when that is ready. Nature knows best. So stop removing leaves. Leaves are a sourve of energy!

Mossy moss wrote: I don't know much about azaleas

Then why would you post in the first place?

Mossy moss wrote: Did you liquid fertilize it? If you did, I congratulate you for burning your roots.

There is no such thing. If you fertilize by the label instructions, you can not "burn" the roots.

Foxallrl wrote: I bought an azalea for 4$ from nursery stock. the leaves were pretty yellow, and I knew it was sick .

Oh no! I have an azalea, the leaves are pretty yellow and the roots are filling the pot so it must be sick too . What should I do?

Remove all the yellow leaves, and repot it right now with an aggressive root prune. Obviously, duh..
Especially if you like russian roulette

Madartej21 wrote: Remove all the yellow leaves, and repot it right now with an aggressive root prune. Obviously, duh..
Especially if you like russian roulette

Yes, but this is a recurring problem. The same thing happened about a year ago. What do I do to prevent it?

Do you let it flower?

Move to a better climate where they keep their leaves in winter.