I'm not sure if mine will keep growing as far as until Christmas..but I've got some still with green tops and going on strong.
Variety I don't know..I had few potatoes left in storage that I didn't use ..those had good 'air spuds' on. I removed the tiny little things and potted them on into 3" pots and they took off in speed..that was in Late-July. Couple of weeks later they were re-potted into 1 litre pots and couple of weeks after that they went into big buckets...by this time there was tiny marble size potatoes already on!
I've already harvested few buckets for tasters..but the spuds were still quite small. As we haven't had any blight in our area..so far..the buckets been outside untill week ago..now the last ones are in GH..and I'm letting them grow on untill the tops die naturally.
If the weather don't turn really really cold, I suspect my taties to go on couple of more weeks at least..and if I leave the potatoes into compost..by christmas they should still feel like 'new' potatoes. Without heating in GH there is no chance keeping them growing any nearer to the C-day.
