This experiment is very much a real time one with none of the clear vision of hindsight. I know from the bloggers' meet in Oxford that other growers including Mustard Plaster are trying to grow potatoes from true seed.
It was new to me as I'd always grown potatoes from seed potato tubers, bought in each year as I'd never been able to store my tubers in good condition for planting the following season. And we'd always been told that we couldn't guarantee that our tubers were disease free.
Anyway, introduced to the idea at the bloggers' meet, I found some interesting and informative sites which got me going on this experiment - have a look at the International Potato Centre and this post by Daughter of the Soil .
I picked these potato berries from my crop of Cara (this year there were loads of berries on my maincrop but none on the Charlotte).
The berries were ripe, soft and sweet smelling, like the ripest bunch of grapes you've ever come across - a potential danger if you have children or pets around as the berry is packed with poisonous glycoalkaloids, 10-20 times that contained in tubers that have turned green. Don't eat them!
After scraping out the seeds I'm treating them as I would tomato seeds and have them in a jar of water to ferment for a few days. I don't know if I need to do this but it should remove any seal around the seeds that could inhibit germination. Then I'll dry them on paper and store for the winter.
About 8 weeks before the last frost I'll sow them indoors as I would tomatoes and eventually (assuming I have germination and no damping off) transplant them to the potato beds and wait and see what tubers I get. I don't think I'll get an exact replica of the parent potato, Cara, and it's likely there will be unexpected variations in tuber size, colour, taste, disease resistence etc. I suppose if some plants do better in my garden than others then I could develop stock from these - really back garden plant breeding.