That is a good question. My sprouts were a foot long before I planted them.

However, last year I covered several plants with dirt in my bins accidentally. None of them ever came back up. They were already sprouted though, so it is not exactly what you are looking for.

Good luck in your search. After seeing your tower, it looks like you are doing everything right. I agree it is more work than throwing them in the ground and watering. If I had the room I wouldn't be using my bins.

If I had the ground I'd do it in the ground too. But I don't, so containers it is. Much more work than throwing something in the ground and walking away.

Dan

I'm trying garbage bags, doesn't seem like much work at all.

One of them was snapped and bent over after a wind storm. I stuffed the bag w/ straw and raised the sides up a bit to support the main stem I was standing back up. Every thing is still nice and green. Of the 3 bags it's the middle in height and is staying that way. It's been over 2 weeks since I did the repair.

I tried one this year too but I found out too late that I got an early season seed potato...Yukon Gold. Pointless to add anymore than 1 foot of compost as the stems grow. If I had gotten a late season variety, it would be a different story. I would be adding 2x4 squares as the plants grew and adding soil up to almost 32'' worth. Theoretically I would have gotten 30+ lbs of spuds. There is always next year!