My husband owns a lawn care company and was recently asked to clear out an overgrown patch by a doggie day care. The slope is very steep, I would say over a 45 degree angle. We took out tons of grape vines and I'm not sure what the other woody vine thing was. The soil underneath is beautiful, as it has been untouched for what I would guess is 30 + years.
We want to plant a ground cover in the area to prevent erosion and for weed control. In the summer, I'm sure it turns into a mess of poison ivy and other junk. I was originally thinking we could go with mountain laurel, but then I thought that would take too long to get established. I think we are fighting some pretty serious weeds here AND this is a one time deal. We basically have to plant it and leave it.
I was thinking of hairy vetch with clover. But I wasn't sure how the vetch would work, as I haven't' found anything about if Vetch would be a self seeding perennial.
A mix of different things will give the best cover and erosion protection.
The things to look for obviously are deep roots and shading out of unwanted volunteers.
clovers, hairy vetch, buckwheat, lupines, Sainfoin, mints, marigolds, etc. would not only do the job needed,
but they would also give back with flowers, no need to worry if dogs go crazy on the slope, all of the above will
reseed and or are perennial in nature, don't really need any care either.
even some herbs such as rosemary could be good additions to a mix, then you have a bonus of plants that deter ticks, fleas and other nasty dog loving bugs.