I've been growing many chilies for the last five years or so, only last year I tried overwintering them (I wanted to experiment). I brought them in on the windowsill but the house was invaded by aphids, literally (lots of them flying around and sticky substances around the window). I managed to control them to some degree by giving them a jet of water in the shower, but after about two months of doing this, I'm starting to wonder if it was worth it. Those I left in the conservatory didn't make it, but the ones in the house on the windowsill was ok. In late winter, I gave them a drastic cut until about 20 cm of the soil level. They grew back very well, but now at the end of the season I also find their fruits are not as big as those I started from seed this year, though there are as many of them. So, I think the conclusion of my experiment is it's not worth the effort of trying to keep control of the aphids for the whole winter. On the other hand, lots of the fruits are still green until now so I don't really want to kill them yet. I have one more experiment I want to do: overwinter them, and in late spring give them a hair cut and root cut, then re-plant in new compost. Maybe then I'll get a good result?