I hope you have resolved by it now. We have a hill in the back yard as well and I was looking on here for ideas. I would mix some stones into it (as simple as limestone rip rap)to help slow down the erosion. Mix some topsoil in. Sow some sunny wildflower mix seed. Maybe even make a few paths and small sitting area that will draw you up there. A bird bath maybe. Keep it low maintenance. I hope that wall has some drainage. Hills are for heroes.

Unfortunately, your photos didn't come up. Since you are new to MAG, forgive me if I state advice you already know. But in general, last summer was a pretty weird year for gardening around much of the Washington DC area. First we has a very warm winter with lots of insects and weeds surviving. Then we had alternating bouts of cool and hot, humid weather throughout the summer with some spots having droughts and some drowning in floods of rain depending on where you lived. Depending on your local microclimate, it could have added up to a not stellar growing season for 2013. It was so in my yard and not much new I planted late got watered enough to really take.. That being said, the first thing is to check the health of your soil to see if there is too much compaction or not enough organic matter or too much moisture (or not enough drainage). The easiest way to do this is this spring when the soil temperature (not the air temperature) reaches 50 degrees F and the soil is dry enough that it will not form crumble-resistant balls when you squeeze it, stick a shovel in the soil and look for earth worms. Few earth worms, and you know you have a soil problem and most likely one of the above three. I would do this on each terrace where the growing was bad last summer first before I considered other problems..

Ivy can be a nightmare for everyone involved unless controlled and that would be hard to do on this hillside. I have decided to recommend Rockspray Cotoneasters to fill in. In my own experience I have found if the ground is shaded whether it be by groundcover or dense shrubs, weeds for the most part do not thrive. If it were me I would put lots of daylilys, rudbeckia, spiderwort, gooseneck and cover with lots of color. But alas, I am an avid gardener and she is not. Everyone wants an easy quick fix and as in life it doesn't work that way. Thank you to all for your suggestions. I was hoping someone had a suggestion I had not thought of but it is a difficult space.

'Lipstick' ornamental strawberry grows like a groundcover, with attractive light pink flowers. It grows more easily than regular strawberries, and is considered suitable for climate zone 10. They will still need consistent water though. Taiwan Raspberry (Rebus Pentalobus) is another unusual groundcover. It is easier to grow in Southern California than regular raspberries.