should i limit my cucumber growth?

I've got a couple of cucumbers growing in 25x20x30cm deep pots on m windowsill (in edinburgh, scotland)
they look very healthy, have just begun flowering and are approx 1 tall, 8 leaf-branches with flowers.
They look like they are still pretty keen on going upwards, but i' concerned as to whether the size of the pots will be detrimental t their fruit production - will they cope? should i prune them somehow or will they find their own limits?
up until now i've been feeding them once a week with seaweed extrac and haven't pruned them at all.
-- jeffcapeshop
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