Warmth and food! Have you anywhere that's cosy and bright to keep them? I'd repot at least the bigger of those into some tasty rich compost, and possibly put more of the stalk under the soil. (This works for tomatoes, at least.) Pinch out the tip at about a foot tall, if they get that big, to encourage fruiting.
Athough, we have almost given up on peppers, at least outdoors. They need a warmer climate for any sort of decent yield, I reckon. Or better allotmenteers.