acar,

You have to slow the water down. The next time it rains, watch the water path, really observe it. Are your gutters, if you have them, facing this hill? How does the water run?

I'm surprised the soil, by the tree roots, is moving like that. Doesn't the tree have leaves that keep a portion of the hill reasonably dry when it rains?

Anyway, mondo grass is a joke. I live in SC, zone 8, down by Augusta, and trust me, that stuff doesn't hold anything. They do sell a special mulch, it's cypress, cut in slivers that is good for hills. It stays where you put it, even in a hard rain. Home Depot sells it. Go buy some of that, 2 bucks a bag. You have to wear gloves when applying it, also, watch where the water runs before it gets to your tree, and go buy some nice big rocks. Rocks will slow the water path down some, trust me on this, it works. You can make it look nice, really.

Daylily are great! They have roots from haites! If its not too shady under the tree, like around the tree, or before the tree, plant some daylilies with the rocks, it'll look nice.

Lirope under the tree, if you want the clumping kind, it won't spread as much, and they bloom even with alot of shade.

Consider planting some ornamental grasses in the water path too. They are amazing when it comes to holding soil where you need it, and you can buy any height and size. Use those with rocks. Looks nice.

Good luck to you. I totally understand your problem. I have been planting all that stuff for 6 years, and i am still working on it.

butterfly4u ,

Unfortunately I started planting some dwarf mondo grass.....Lowes was all out of the $2 small plugs of liriope, but they had a lot of mondo grass.....I ended up buying 10 pots and planting it. Hopefully it will take hold and help solve my issues. I will get some of that Cypress mulch as well and put around the tree.