In article , axelbrora axelbrora.1
writes

I have tried growing potatoes for the first time and harvested the first
ones today to find very few and very small potatoes.

I used proper seed potatoes from Dobbies, chitted them for about 4
weeks in the greenhouse, and they were planted out 11 weeks ago this
weekend and the flowers have fully opened out. I have some in old
compost bags and some in the ground. I tried one compost bag, with 2
plants in it, and one plant from the ground and had the same results.
I think the problem may be one of the following and would appreciate
some advice.

It's simply too early. Best to feel around in the soil for one or two
potatoes to check for size, rather than harvest the whole lot.

I don't grow potatoes, merely let them appear in the garden, and they
certainly don't get any fertiliser, but still grow large.
--
Kay
"Do not insult the crocodile until you have crossed the river"