Aubergines

perhaps they are not getting pollinated, use a soft brush to move pollen from one flower to another.

what should you feed them on? mine get the same as tomatoes and are not fruiting well

From my experience, growing similar plants at the same time in a g'house, aubergines need more space per plant  so they get more light/sun, keep away from door or vents as they dont like draughts/ temp changes

hope this helps

No idea if I'm doing it right, but I have a reasonable crop

Mine are in a row between Tomato plants (along the central path) and melons (climbing the glass sides), so they don't get a huge amount of light, but they do have a reasonable amount of space - there is about 3- - 4' between Tomato row and Melon row, and about 2' between Aubergines in their row.

They are at the far end, away from the door, so no draughts and a bit more humidity.

They are planted in the border, not pots / bags, and are watered twice a week - about 1/2 gallon per plant.

I don't pinch them out (but I would if they didn't branch by themselves, same for Sweet Peppers, but I can't remember having to pinch them out either). I feed them with liquid Tomato fertilizer - which goes on the Sweet Peppers, Melons, Tomatoes and Cucumbers too. I don't pollinate mine (not enough time), but I think it would help.

Variety is Black Enorma, which fruits early, and Black Beauty which comes later but has softer , tastier,  fruit IMHO.

Around the beginning of August I look out for mottling on the leaves which generally signals the arrival of Aphids, and I spray them (soapy water if not too bad, this year I had to spray them with some noxious chemical)

sorry...you'll just have to join the queue