Floating Mulch Solution: Installing A Small Retaining Ledge

Our front yard is pitched from the house down to the street.  There's a significant grade difference between where our house sits and the curb such that our yard is on a slope and parts of our parkway are on a pretty severe slope.  But, so, too, are the beds in front and on side of our front porch.  You can kind of see/appreciate the grade difference in the photo above in this post.

This is a profile view of the area that you can see in the photo on this tulip post from last year.  In that photo/post, you can see how the grade from about halfway back on the house all the way to the front of this bed is downhill.  But, it also slopes away from the foundation, too.

This area is where I get the most erosion in any of the beds around our property.  We get rainwater erosion and plenty of floating mulch.  A couple of times a year, I break out the rake and pull the mulch back into the bed.

Here's a post showing all the mulch in place.  If you look at the white boards on the skirt of the porch, you can get a sense for the grade changes.  It looked great when it was stocked full of mulch, right?

But, look at the most recent post from early October of last year.  At the base of those hydrangeas is no longer mulch.  It has mostly all washed away.

Compounding the issue is that I switched the front of this bed out to cocoa bean hull mulch - which you can see up close in this post showing our tulips recently.  I think that cocoa bean mulch floats just as easily - if not more - than hardwood fine mulch. 

I mentioned earlier this year that I was considering extending the bed in this area to potentially add another tree in front of the larger Maple that we have up there.

So, what would a solution be for this area?  I'm thinking that it will either require terracing - a series of steps down with one-level retaining walls.  Or...something more significant down at the end of the bed.

For reference, have a look at this one larger flagstone piece that we have in place that provides a bit of a terracing-effect:

The other option is to build something more prominent like this:

It seems to me that the terracing version - without the front-facing wall is the less invasive/noticeable solution.  But, does it solve the problem?  Seems like I'm going to have to find out this Spring before I apply the mulch to the front beds.