For some reason, the potatoes we get in our produce delivery box sprout a lot more quickly than the ones we get at the store. I'm guessing it has to do with their freshness and variety. The ones above started growing little stalks after a few days--or at least that's how it seemed.
Rather than chuck them in the compost bin, I decided to plant these taters and see what happened. I had a rather spectacular failure trying to grow potatoes in bags, so this time I just dug a deepish hole in the upper garden bed and buried them, with room to add more dirt and compost as they grew.
To my delight, they shot right up! What's nice about potatoes is that the stalks grow extremely quickly. I planted the sprouted potatoes in late March, and by mid-April they were in need of some more serious mounding. So, I built a little wood barrier around the plants and buried them a bit more. If I had more time, I'd build it even higher. But I think one level will have to do for this year.
Since I haven't grown potatoes successfully before, I did a little check last weekend to see if the plants were actually producing new tubers. I dug up two stalks on the edge of this patch, and, happily, found some teeny tiny baby potatoes growing deep down in the soil. So, I may actually get some homegrown potatoes this year, if I can keep curious chickens and evil skunks away.
I think they key in Southern California is to plant potatoes in the late Spring. Once summer really begins, the plants have difficulty in our dry heat. At least that's my experience.
This year I tried stacked tires, an old cracked 35 gal trash can, and a 'pit' in the ground. All of them have enormous leafy vines like yours, but I haven't checked for tubers. Somewhere I heard that the plants actually produce little flowers, then die back, and that's when they are ready to harvest. I have yet to see any flowers, even though my 'pit' has produced some nice potatoes for a couple of years. Do yours have flowers?