I hate aphids. I notice they typically get bad when the plants are stressed (maybe heat?) and when they get old.

Its not a good idea to spray chemical for aphids. The main problem there are many natural predators that keep aphids in check, and when you spray it kill them too. And aphids become resistant to many pesticides.

The best way I have been able to deal with them is to try and encourage natural predators. I will not spray chemical to kill them. When I find ladybug larvae around I put them on my plants. I also spray off the aphids with a stream of water, that also helps. it takes a while but with patience it does help. In a natural garden without chemicals, the predatory beneficial insect populations always eventually catch up and bring the aphids under control.