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.

1. It is simply too early to lift them, despite the books saying 10-12 weeks and ready to harvest when the flowers are fully open.

2. The ones in the old compost bags, which were refilled and continually earthed up, with B&Q's Multipurpose compost have not had enough fertiliser or manure to produce a good crop. They have only had the B&Q Multipurpose compost and the fertiliser it contains.

3. The ones in the ground have not had enough manure or fertiliser. The area is about five square meters, first time cultivated, and I used the top soil which was turned over, some home made compost and mixed in a bag of farmyard maure from Focus. The bag was about 50 litres and cost about £3.99. I earthed them up with home made compost.

4. A combination of the above, too early and not enough fertiliser.

Axel