Thanks everyone for all the advice.
I have had to chuck out my c****bis plants. They just collapsed.
Maybe they didn't like the insecticide spray I used.

I sprayed my dragon tree that the spidermites originally came from with a
fly spray, and I nearly killed it. Besides, you shouldn't really use
insecticides on anything you are later going to burn and breathe in (or
ingest in some way)!

I did also start
misting them, but they are now beyond revival! They were very badly
affected with the spider mite.
I have a few more seeds so will try again when the weather warms up.

The predators I bought for mine seem to have done the trick. Shame about
your plants. They may be "weeds", but I find they are very sensitive to how
they are treated.

I would recommend the predators.

Andrew