The plan is groundcover. But while waiting for groundcover to fill in, I need to mulch. And one heavy rain will wash all the mulch downhill. What to do to keep the mulch in place?

In that area, I wouldn't bother. Just plant the groundcover more closely spaced than otherwise.

The truth is, I'm not seeing an erosion problem. The tree roots probably do a good enough job of holding the established soil line. What I do see if a lot of unsightly bare ground which would look better with groundcover.

What is the realistic traffic pattern through the side yard and this gate to the back? You also have utilities and house mechanical of some sort on this side. Is there planned easy access to that? Does this area deserve a well constructed pathway?

The slope into your neighbor's yard looks natural and long established. That is the only way water is going to flow. You currently have two open gutter downspouts directly aimed at this area. Those are the likely source of any erosion problem. They can be jointly connected to buried pipe and directed to a better discharge location.

Normal rainfall doesn't really move mulch on a slope that gentle unless it is bark mulch that wants to float or a river from the roof or downspouts is running through it. Ground hardwood mulch is only going to move with a very strong current of surface water.

Mulching and planting the area with a well chosen shade tolerant, moisture loving groundcover isn't really a problem. Planning for the needs in this area, the realistic traffic pattern and dealing with the gutter downspouts are the big issues that should be addressed for a long term stable solution.

"The plan is groundcover." OK ... but you didn't mention or explain it yet, so we can't know details about your intentions. So far, I've only heard you mention a line of Liriope. But this was mentioned being used as a low hedge, not as a groundcover. So I don't see that it has any real use except as a feature to trip over. What's needed is a low groundcover that can be walked on occasionally. What will you be using?

I agree with others that if you plant a groundcover at a reasonable spacing and mulch it, the mulch will more or less stay. If a little washes away that's not of much consequence. And the groundcover will be taking over and eliminating the need for future mulch ... which will be tree leaves anyway. The groundcover should be one that "eats" tree leaves in the fall.

Where should the buried pipes that connect with the downspouts lead to? To the front lawn? I am getting a 2'-3' wide walkway put in. I don't know which low growing groundcover to use yet. This is part of the front lawn connecting with neighbor's lawn, so I cannot use invasive groundcover or things that are considered "weeds." Maybe I'll make one more attempt with the shade grass this fall.

The buried drain pipes need to use gravity so they have to go downhill. Without knowing a whole lot more about the house and drainage situation over all, I can't say where the best place to discharge the water back to the surface is. That might be under your fence and into your backyard. I have no clue.

You are not going to get good specific groundcover plant suggestions to use when nobody knows where you are located. Location matters.

I am in northern virginia 7a. I concluded from my other thread (regarding my backyard,) though, that there is really no low growing groundcover that survives dry shade and tolerates occasional walk-on, except maybe drarf mondo, which grows extremely slow and thus is expensive.

Pretty much any groundcover - except the very succulent types like stonecrops - will tolerate some light foot traffic......just not regular or routine foot traffic.

Ajuga, Vinca minor, Pachysandra terminalis and Lamium maculatum will all thrive in dryish shade. And will tolerate the odd trek through the area.

The oil delivery man tramps
through my pachysandra monthly through the winter and that isn't a
problem. It only becomes an issue if the tramping is daily.

Also, straight species Mondo Grass, Ophiopogon japonicus, is not as slow as the dwarf form. If you ask around you may be able to buy that or possibly even get it for free by the garbage bag full.

I would advise you not to run downspouts underground. All you're doing is taking a concentrated flow of water and discharging it elsewhere. Not only do you risk trouble later (clogged underground pipe), the "elsewhere" would be near the bottom of a hill which in your case might be very close to a neighbor's yard. A universal regulation in communities is that you cannot discharge a concentrated flow of water into the neighbor's yard. If it ends up causing them problems, you would be responsible for rectifying the situation. If you get plants to cover the ground, instead of bare washed earth, then you will solve the problem. And the expense and work of burying a pipe underground does not alleviate the need to establish plants anyway.

"Maybe I'll make one more attempt with the shade grass this fall." That is like suggesting that even though socialism has brought misery to people wherever on earth it has been tried, that we could rename it and try it again. Look again at how well the grass that used to be there is doing. I think all the pros here are telling you that grass is not going to work. Nor would it be pleasant to mow on the slope even if it did work.

" I cannot use invasive groundcover." There are some people who would call nearly any groundcover invasive because it spreads laterally, which is the nature of the plants -- having the ability to cover the ground. This is usually a asset when getting groundcover established as it limits cost. But it usually means that where groundcover meets certain objects, it might need to be trimmed, or "barricaded," so as not to overrun them. A lawn must be trimmed and edged more or less weekly so as not to become a problem. A groundcover's height is automatically limited by genetics and usually only needs its edges trimmed. And usually, much less frequently than a grass lawn. Take a good look at the neighbor's yard. I would suggest that they are also in need of a groundcover. If you both had the same groundcover there would be no need to worry about it at the property line. I suggest you pick the right one and lead the way.

Surely there are other shady, sloped areas in your town where people have ALREADY solved this problem. Take a look around and see what groundcover they used as it is probably the groundcover that will work best for you, too.

There are, but they either have grass or weed or both. Only houses with full sun yards have professional landscaping.

Thanks everyone for your suggestions. I see now I might have gotten the wrong type of mulch before. I think with a stone walkway & hostas/liriope on one side, it should hold the mulch in place.

Wondering though, why people seem to like pachysandra over periwinkle/vinca minor?