Why aren't my eggplants producing anymore since June?

Eggplants often stop producing when it gets too hot and dry, especially in late summer like right now. Make sure you're watering them regularly (the soil should stay moist but not waterlogged) and they're not in intense direct sun all day long - a bit of afternoon shade helps. It could also be a lack of fertilizer if you haven't fed them in a while, or pests like spider mites that get aggressive in the heat. Try misting the leaves in the evening to hydrate the plant and reduce the sun intensity if you can.