We don't 'feed' any veg. once it is planted. We do feed the soil before planting though.

You can water in any proprietary plant food. They will appreciate any that you can give.

Runner beans as legumes make their own nitrogen from the air with nodules on their roots, so they don't need 'feeding' as Moon grower says. What they do need is a deep water retentive soil so that they are never short of moisture at the roots.

Thanks Bertie was beginning to wonder if I'd lost the plot!