Posted: 12/04/2014 at 20:37
Personally I don't like that fabric stuff. I have a similar steep bank ( although not as long as yours) and have bark on it fine, so I suspect it's the fabric thats making it slide. Mine's recently planted and so lots of gaps too, but I'm not having much trouble keeping it clear of weeds- I get a few but a wiggle with the hoe does the job.
So, I'd remove the fabric and put the bark back directly on the soil. Were there weeds underneath? If so, you'll have to get rid prior to barking. Or perhaps put up with it for a bit longer and hope the darkness under the fabric kills them off.
Geraniums are good call - they're my go to plant for ground cover! One of the helpers in my grounds elder battle....