Tomato fertilizer seems to work very well. Late winter is the best time to start. then once a month during fruiting period. They are ravenously hungry & thirsty plants.

Agree tomato fertilizer or sulphate of potash in early spring to encourage flowers and fruit but also in containers you will need some balanced fertilizer a little later on - they will soon have used up what was in the compost originally.

Thanks Paul and Sg for your replies. Tomato fertiliser it is then. I will also use a balanced fertiliser later in the season as you recommended Sg.

You can buy sulphate of potash as a dry powder and this works out cheaper than tomato fertilizer - if you are going to give a general feed later in the year its an option to consider. I do this on my gooseberries and usually get a bumper crop.

Many thanks for that further info Sg I will bear that in mind.