I had GREAT success with containers last year. A 5 gallon bucket is perfect for peppers. I had 1 Celebrity tomato in a 18 gallon tub that kept my wife and I supplied all season long. I snuck a few cucumbers in her flower bed had cucumbers coming out my ears. The cucumbers I planted in another 18 gallon tub developed and produced faster than the ones in the ground. For shit and giggles I put some potatoes in after the cucumbers had died off and ended up with 5 pounds of baby potatoes for Thanksgiving. I bought a bag of red onions for 3 bucks at Walmart..not quite sure how or where to plant them.