Using potatoes that have rooted in the cupboard!

Do you have to plant seed potatoes or can you plant normal potatoes that have grown roots in the back of the cupboard? Potatoes ´go off´ very fast here, always get roots before you can use them.  I usually throw them away if they get too bad.  Is it worth the effort of planting them up?

Thanks Heather_S  I didn´t think of that!!  So it is better to be safe than sorry

I take it it would be fine to grow your own potatoes from the cupboard that you grew previously though?  Do you have to do this the same time the following year, ie early for earlies etc or is any time OK?  Hope this makes sense. 

If you want to try them, grow them in a big potato bag or pot and not in the ground, then there is no chance of disease to other crops.
Why not just pop out and buy some seed potatoes, they are hardly expensive and the yield always well justifies the small outlay.

I do it, we have our veg delivered in a local box scheme, that and some that had sprouted from last years crop, did it last year with good results and no problems, and have done it again this year, plus about 30 proper seed potatoes from sainsburys. I was told by a lot of people that the crop would be deseased, but as I say mine werent supermarket potatoes, just local farm ones from the veg boxes.
Grendel