Gallons work fine. I always pot mine up from wholesale vendors and keep them over the winter. I was just looking at mine from the co-op and from Donahue, and I haven't lost a one. Isago was the strongest grower, growing out the holes in the pots and into the ground so much that my husband had to dig them out.
If you can get pine straw mulch I put some on top of my pots so no weeds. You could also sprinkle a little weed preventer on top of the soil.
