Plant suggestions please!

[MrsBertBibby]

I have a problem zone, which is a very steep border mostly held up by roots.

Top left, a magenta spireaea, right a yellow potentilla, in between is a globe thistle just getting sprouting. The problem is that the bed is infested with campanula. It is ineradicably in the roots of the shrubs, so although I have just dug a lot of it out, it will return. It's OK but not in such profusion!

So , what might you suggest that will give good ground cover (and hold the soil up so it doesn't wash down) under the shrubs?

Preferably in blue/purple shades, but open to others. We're on chalk so quite free draining and alkaline.

Thanks!

Could, at a push, if you're entirely fed up, have a judicious blast of glyphosate.
Ajuga or aubretia or lamium are good ground cover- think your best bet here is to add enough of various things like these, which all tend to spread, that they at least form more of a patchwork.
Unfortunately a lot of the more ground cover type things aren't especially deep rooted though.

I will admit to trying glyphosate on a patch out front. It only made it happy.

Honestly, it is a bastarding thug of a plant! It is pretty enough, and the bees love it, but it would seriously take over the whole bed if I let it. So I'm hoping to come up with something that will give it a run for its money.

What is it you don’t like about the Campanula? Because it seems to me you are asking “what blue thuggish flower can I plant to replace the blue thuggish flower that I have?”

I'd like it well enough if it weren't so hell bent on being the only flower I can have! I like a bit of variety, so if I can find a ground cover that can stand up to it, that would be great, as I am absolutely stuck with it, no matter what.

My go to ground cover would be geraniums, . You could also try one of the smaller nepeta which clump up well. I would also try salvias.

I don’t know how any of the above would do on chalk though since I am on well tended London clay.

I have some similar bits in my garden and aubretia and ajuga thrive there. Also, I was given a few primula plants by a neighbour (deep purple ones) and they are very happy there. I've also stuck a couple of lavenders and some mint in and they're happy too. They all just need regular taming.

Another vote for lamium here .

How about a prostrate rosemary?