It also depends on the type of potatoes you use. I grow fingerlings in Rubbermaid tubs of different sizes and get a fair yield. I put drain holes about 2" above the bottom and do have to water them regularly WITHOUT OVERWATERING. Also don't overload a tub, instead use two or three tubs. I've tried the towers and bags and always do better with the tubs. I use these for early potatoes and for the grand kids to gravel.
There are three sets in this one and it is one of the last left. My Grandkids have graveled out the rest of the tubs.
Here are some graveled a couple of weeks ago by my youngest grand child before I wash & split them, boiled them 2/3rds done, then fried them crisp in bacon grease. He loves them better than potato chips.
This is just about a third of the ones for this one set. After the grands gravel them out I cover the area with dirt and let the rest continue to grow.
The type of soil makes a huge difference in potatoes. I live among some of the best field corn and soy bean ground in the world, but it is heavy and if it isn't prepared yields a small crop of potatoes.
Any potato areas in my AO has to be conditioned before thinking of putting in seed potatoes. Lot's of well composted manure and other organics tilled in to make the soil as loose as is possible. CAN't PUT SAND IN MY SOIL- it will make it set up like concrete. You want loose soil to get better yields and larger potatoes.
My tribes main garden is at my daughters farm and her husband worked in composted cow manure for two years before we were going to start using the current main one. That and a green manure crop during the winter and tilled in the late summer. The potato area will be moved for next year's crop.
I also have two 40 foot rows of potatoes between the fence at the back of the sheds and the west field at my house. I use it for new potatoes and some odd varieties that I like. Next year I'll move it north down the fence line for two years.
South of gate North of gate
I have 7 different types of potatoes along the back fence. As you can see in the picture on the left I've already dug a few hills of some Yukon Golds to check. To the normal person who would happen to wonder up on a fence line with potatoes scattered along it, they wouldn't have a clue what they were seeing.