I'm growing potatoes in a 5 gallon bucket. The mature leaves are a beautiful dark green, as you can see in the below photo, and the plant is growing fine, but occasionally the young, small leaves growing off the tip of the stem will start yellowing. You also get a bit of yellowing at the base of a middle-sized leaf. The yellowing has come and gone once or twice over the lifetime of the plant but I have not figured out what factor is causing it. What could be the cause?
I put the tubers in the soil around 11 weeks ago and it has not flowered, although I believe this variety is not expected to flower. The bucket has ~10 holes drilled at the bottom, maybe an 1/8th of an inch in diameter each.