Wait until the last chance of frost is past. That is probably in mid-May. Most azaleas sold at Valentine's day, Easter and Mother's Day are florists azaleas and are not hardy enough to overwinter outside. In that case you will have to bring them in next fall before we have a frost. If they have a name, you can google it and see if they are a hardy variety. I am guessing they are not.

You must be doing a good job if you are keeping them alive. Their biggest enemy is wet roots. They need good drainage. Never keep in a container that retains water. The need a pot with holes in the bottom. They also should only be watered when they are getting on the dry side.

Here is a link that might be useful: Care of Greenhouse Azaleas

Hi rhodyman, and thanks so much for your response and the link. I'm as surprised as you are that they're staying alive. Here's hoping they stay that way until mid-May, or at least until the last chance of frost is past.

I really appreciate your help,
Cristina