I've done "xeric" conversions by killing the existing grass with Roundup, then mulching. The "lasagna" style or just a couple of layers of landscape fabric works well. It's not 100% weed-free. Dig right through the sod to plant - whap the clods to get the roots out of the dirt and fill the holes up with native dirt.

The trick is to water the grass really well for a week or so to get it growing fast, then spray thoroughly. Mow it really short, leaving the clippings. Water well for another week or two to lure the survivors up and spray them.

Oh, I like lazygardens idea! The dead sod would help hold the slope together. Don't skimp on the fabric by using plastic, it creates an anerobic condition in the soil (airless) that isn't good for plant growth.

Question: is the slope so great it won't hold a mulch? You'll need to cover the fabric with something. The dead grass doesn't thrill me.

For water can you use drip irrigation? That will help reduce weeds.

Tip of the hat to lazygardens!

Thanks very much for your responses... I think I'll do the roundup route, plant and then do the cardboard, mulch lasagna trick.

Any ideas how long I have to wait after applying roundup before I can plant?

Thanks again! This newbie needs all the help she can get!

Here is a link that might be useful: Krystine's Garden Blog

My understanding is that Roundup doesn't persist in the soil. According to the label, you can plant flowers the next day. I'd probably wait at least a few days to a week for anything edible.