I am using six 30 gallon grow bags on my grow bag table. Each one is two feet in diameter and 16 inches high.
I usually use 3 bags for potatoes and 3 bags for sweet potatoes.  Since potatoes are in the Nightshade Family and sweet potatoes are in the Morning Glory Family, I just rotate between the potato and sweet potato bags each year – how easy is that for a crop rotation plan! Also, since I can plant and harvest the potatoes earlier, I usually plant a fall crop like carrots, bok choy, arugula etc. Since I usually plant the sweet potatoes around the end of May, I can plant a quick growing spring crop like radishes, carrots, mustard, etc.
I use grow bags for potatoes and sweet potatoes because they provide good root aeration. Also, it is much easier to find the Tubers.
Since the grow bags are round, I like to get a little creative! The rule is to try and plant them about 8 to 12 inches apart so I usually plant 5 potatoes or sweet potato slips in a 30 lb. grow bag. I know that the bag is round but I think you will get the idea from the pic above as to how I space the tubers. I put one in the middle and one in each of the 4 sections.
