If you do that, I've heard growing them in a sunny spot in deep woods keeps them contained. They don't do well in heavy shade and won’t spread into it.

Im sure you can use that information to passively contain them somehow, based on your own environment :)

I am growing them, they keep looking sad again within a week. Leaves drooping down a lot.

But there has been no rain in almost 2 months so I guess most things would struggle. Just seems like a lot of water I am going through to water everything. 125m² and using a few hundred litres a week.

Edit - Actually given the drought this year is so extreme, probably hasn't been the best time to get into growing veg. Oh well. At least if this year really is unusually bad then anything to survive this year should do better in future.