Experts and BHG readers answer.
What's the best way to plant grape/ blueberry/ blackberry/ raspberry in pots?
It's best to use a good container potting mix for growing fruits or any other plants in pots. The Miracle-Gro potting soil you have should work well.
A good size container to start with for fruit plants such as raspberries, grapes, and blueberries is a one gallon nursery pot. These are deep enough for the plants to develop a sturdy root system, but not so large that the potting soil will remain too wet between waterings. If you intend to keep the plants in pots all summer, transplant them to a larger container once the roots fill the gallon pot.