Once potatoes start sprouting.....well, they ideally need to be green chitted then while the sprouts are 3/4 inch long so that they remain short and stocky. I have seen the potatoes hold pretty well for a month after chitting if left out in the light. If they are refrigerated, they will kind of hold for a while. If the sprouts are broken off and the potatoes are kept in the dark and refrigerated, I don't know about them then. This post was edited by wayne_5 on Sun, Feb 2, 14 at 19:39

I can't say that they won't keep growing, but I would stop now. I have one board left that I could add to my bin but the foliage growth has slowed (pretty much stopped actually) so I'm only adding a little more straw just to replenish where it's settling down into the box. I don't think I'll get to add the last board. I would imagine that once they start flowering, their energy is going to move to tuber production rather than top growth. Here is a link that might be useful: Tales of a Transplanted Gardener

Many seed companies just recycle last years seeds. The garden centers ship them back to the distibutor and they test to see of the seeds are still germinating. If they get good germination rates, ( not sure what the percentage is), they just repackage them for the next year with a new date on the package... so your seeds may actually be older than the package states. It kinda defeats any knowledge of how long seeds actually last, but also encourages me to keep seeds a long time. If the seed companies are recyling seeds each year, I can too. On a side note, I am growing peppers from seeds I bought last year and from seeds I saved from a pepper last year, and the ones from the pepper are growing WAY better. Maybe because they are fresher, or it could be the variety. Just food for thought.

Had a discussion about this just a week or so back. http://forums2.gardenweb.com/discussions/4536434/seed-potatoes-sprouted-a-lot?n=10 Most recommended removing those sprouts or at least rimming them back. And one of the other posts about this said "When potatoes sprout in the dark, they are white and long: NO GOOD FOR PLANTING. twist them off." Several other posts about the question the search pulls up but they all mostly agree - remove those. Dave