Problems with growing Potatoes in bags

I need your help, I am relatively new to growing vegetables so apologies if this is a silly question. I decided to grow some late Duke of York potatoes in bags following watching Monty Dons video, it looked easy. Plant them and as they grow keep topping up the compost until its nearly at the top. I planted them in September and they grew really quickly and followed the instructions, there was lots of foliage, but then after 6 to 8 weeks they started to die off, I left them and I decided to harvest them last week. There was little or nothing in any bags, there was lots of small potatoes about the size of a large bean. They had obviously started to grow and then stopped. Have I done anything wrong or should I put this down to an unlucky first effort?
Posts
Did you water them well? Could they have got blight?
hi tony littler as w/onion says did you water and you do not say did you also feed them as that is important also to help with growth
Tony , personally I grow potatoes in sacks in the spring only
I known some people do grow them for Christmas , did try once but sacks just got frozen solid even in Greenhouse so no longer bother
Try again next year and yes they do need watering , best of luck
Hi, Thank you all for your responses.
I watered them well throughout, when I emptied the bags they were moist but not soaking. I did not feed them at all, I thought using a good quality compost would be sufficient however I will do that next time. I think they got blight, apparently it has been a bad season in Aberdeenshire.
I will try again in the spring, I will not give up easily!
Tony
Hello , personally I do not feed them , just rely on good quality compost ad well
Best of luck
Thank you, I am sure I will your advise I will have a successful harvest next year