I have grown potatoes in 5 gallon buckets with the bottoms cut out completely. It worked pretty well. I put a small amount of soil in the bottom. Placed in my potatoes and as the plants grew up I occasionally added soil until the bucket was full. To harvest the potatoes I simply had to pick up the bucket and everything fell out the bottom.

I do the same thing, growing plants in old stock tanks with the bottom rusted out as well as smaller galvanized containers with holes drilled in them for drainage. Rust won't hurt you or the plants. I've grown all kinds of plants, both edible and ornamental, over the years and they've all done really well. Sweet potatoes produce better in stock tanks for me than Irish potatoes do. Remember that Irish potatoes perform better in cool soil and that soil in above-ground containers heats up more from sunlight than grade-level soil. Irish potatoes in hot soil tend to be less productive than those in cooler soil. That won't be an issue in late winter or early spring with Irish potatoes grown in metal containers, but it can be an issue by late May and thereafter. One way you can work around that is by surrounding your metal container with smaller containers of plants. The smaller plants take the direct hit from the sunlight and provide some insulation and protection for the soil and plants in the metal containers. I usually don't grow lettuce in metal containers, preferring plastic containers that won't heat up as much as metal does. This past spring the cool-season crops, including lettuce, in plastic containers lasted a month longer than the same varieties in metal containers. Dawn

Larry, I do think that your soil now is too rich for the crops like sweet potatoes that grow and produce well on crappy soil. The good thing is that "heat eats compost" so the organic matter you added to the soil will decompose and go away and your soil will become less fertile in 2 or 3 years' time if you don't add any more organic matter to that area. That then would allow sweet potatoes and other plants that don't need rich soil (southern peas and okra come to mind) to produce well in the area that right now may be too rich for them. I agree with Lady Nikki that your results can vary depending on how closely the sweet potatoes were planted. I grow my sweet potatoes square-foot-garden style with one potato slip planted per square foot. I do that because I like to grow many different kinds of sweet potatoes but I have to grow them in a raised bed lined with hardware cloth so that the voles don't eat them, and I only have two small raised beds lined with hardware cloth. (I intend to work on redoing some of the beds this winter so I can add hardware cloth to them, which will give me more space to grow the plants that voles tend to devour.) When you plant one slip per square foot in all directions, you get fewer pounds of potatoes per plant, but we still get more potatoes than we can eat before they start sprouting in the spring. I think I grew 9 different varieties this year. At 3 slips per variety, that would have been 27 different plants but Gary always overpacks and sends extra slips (I'm assuming he is allowing for the fact that a slip here or there might fail to root in and grow) so I think I planted about 40 plants in a raised bed that is 40 square feet. I haven't harvested yet and I didn't water them much, so I might not get high yields, but I still bet we'll have more than we can eat. The vines themselves have looked good all year, although in August I probably let them get too dry and they wilted a couple of times, so I may find knobby potatoes when I dig them. Luckily, a person still can eat knobby potatoes. Dawn

No one seems to have answers for you so I'll give you my thoughts. Container planting for veggies isn't one of my favs for suggestions, never had much success with that method other than possibly a small cherry tomato plant for minimum production. That being said, a max of one plant per 5 gal container is your best bet, I say this because later on when the pepper or sweet potato plant grow large it will keep you pretty busy watering the plants. Also black containers aren't the best color as they will get very hot in the summer sun and roast the roots on the inner wall, so it's best to shade the container portion. And 25 gal containers? would not like to move those when the time comes. Sorry for the dismal report, just too used to planting veggies in the ground where moisture, temperature, and daily attendance is less cumbersome (though weeding part is easier). Good luck!