Answer: The annuals you plan to grow will have reasonably small root systems and won't require large pots. You'll be safe with a 2-3 gallon pot for each plant. That's roughly 12" deep and 8"-12" wide. However, I'd consider using larger containers--the smaller the container, the faster it will dry out. I like to use wooden half whiskey barrels. I plant the vines at the back, and plant shrubby annuals in front of the vines.
Terra cotta pots can wick moisture from the soil, especially during the hottest months of the year, so check at least once each day and water as needed. You might consider using "fake" terra cotta containers made out of plastic. They look very similar, and won't dry out so fast. Whatever you choose, make sure your containers have adequate drainage holes, fill with regular potting soil, and water as often as required.
Enjoy your vines!
Q&A Library Searching Tips