I only water after finishing up potting the plants.

You could put them out but a few weeks after your average last date of frost would be safer. If you have good forecasting experience with winter weather in your part of MI, you could take them out. But may have to bring them back inside if Mother Nature makes you say woops. :o)

If the porch provides bright shade it may do fine.

Luis

Thank you! So no soaking the roots? I was told to do that with most bare roots like hostas, roses, etc

Ahhhh.......bare root does make a difference (I have never planted a bare root hydrangea - all of mine have been potted, even tiny cuttings). Yes, you want to make sure the roots are properly hydrated, the same as you want the rootball to be. But you do not need to soak for 24 hours - in fact, that is too long for any type of bare root plant. Just an hour or so is fine or as long as it takes for you to prepare your containers and place them.

So I had both hydrangeas in identical pots for a week and a half. One plant is healthy and thriving. The other has black spots on the leaves and some of the leaves are very crispy.

I have them in self watering containers about 15 gallons with a inch of mulch and new miracle gro potting soil.

They are both on my covered porch where they get morning sun and afternoon shade. Since all the leaves have black spots, what should I do?

Crispy leaves does not sound good. Is the soil dry? Not getting good ideas about what the black spots may be? An opportunistic fungal infection maybe. I think you need to call Hydrangeas Plus and report the problem and see what action you need to take so any warranty will be honored if the plant dies. Write down who/when you spoke with. And what the instructions were.

Don't mean to rain on your parade, but if you want whites in zone 6, I've found that H macrophylla aren't the way to go. If you're closer to a body of water (river, lake) and/or get lots of snow, your chances will improve.

I would lean towards H arborescens (Annabelle, etc etc) IF those don't work out for you.

This being said, them being sited very close to a home and in a sheltered location will greatly improve their chances! :)