Posted: 27/07/2014 at 21:54
You are probably doing nothing wrong, I've found this year some varieties do better in bags than in the ground and probably visa versa.
I'm growing spuds the other way round this year. Grew them in bags for about 4 yrs and this year in the ground on an allotment.
Red Duke of York have cropped about the same in terms of size and weight although they have not been fed and watered as at home or been planted in multi purpose compost so were cheaper to produce.
Pentlin Javlin were the same, cropped about the same from 10 seed spuds but I got bigger spuds.
Maris Peer, 2nd earlies came into their own and had a bumper crop.
All mine flowered this year and they seldom flowered in bags. Bags at home were fed on seaweed feed and planted in multi purpose compost. I've had no scab this year too, in bags some would get scab but I had no soft spuds in bags and had a few this year with Red Duke of York.
A plus with bags, you can try different varieties, I ran out of room to plant out the chitted spuds bought at the beginning of the year. You can also try Christmas spuds in bags.