I have two fig trees now at 4-6 feet high. I'm finding it impossible to locate large containers for them. The biggest I've seen are 22 inches across and 18 inches tall. I bring them inside in the cold months.
Large Plastic Containers
Certified GKH Gardening Expert
Believe it or not, I have had good luck with finding large pots at places like Wal-Mart and Target. They will only carry very large pots for the spring season, but they are 2 1/2 - 3 feet wide and the same tall. You may also want to check your local hardware big box stores. Again, they only carry them in spring, so you would need to go now to find these size pots.