Hugo Morvan wrote:Welcome to Permies Rose!
Nice wall! The earth looks really sandy. water will drain easily then. Not easy to grow things there. Great some weeds are already there building back up this disturbed soil. Their seeds have been waiting for that moment. Usually the green roofs people have turn brown/yellow in summer. The layer is not deep enough so the grass can't get any water from deeper layers. Those weeds look pretty resilient. They might have a deep taproot and be happy enough with not a lot of nutrients. But they keep the soil in place! Very important on top of the root cellar.
The sides are still exposed to the sun and erosion. Maybe pebble it up? And look for some other low maintenance plant on your terrain that could grow in between those pebbles. You need the roots to keep it all in place.
If it were me i'd let the weeds do their thing and plant something down the sides that can root deep and cover the top. Wisteria springs to mind. It will fix nitrogen at its roots. Maybe chuck in some left over wood debris into the weeds so the wisteria got something to grow above the weeds and shade them out and take over slowly.
Jay Angler wrote:What about naturally low-growing shrubs like wild blueberry?