We recently bought a house and are finally tackling the outside areas (spent the first few months on interior renovations...my wallet says "ouch!"). We are located in the San Francisco Bay area, and would like to replace our grass (+ weeds) lawn with a fast spreading, low maintenance, drought tolerant groundcover.

The front lawn is being taken out today (!!) and we will get a layer of topsoil in its place. I plan to plant two types of sedum: sedum rupestre (Angelina) and sedum rubrotinctum (jelly-bean).

As both are spreading plants, the recommended planting distance is 10-12". I currently have several flats of each plant from the nursery - I plan to separate each flat into ~25-30 plants, and space them 12" apart. Do I need to mulch in between? Do I need landscaping fabric? Should I just leave the in-between soil as-is, and be really good about weeding while the plants establish and spread? The lawn is somewhat sloped, and it does get windy frequently - I am afraid that all mulch will simply blow away.

I have never planted succulents outside before, so would appreciate any advice. Thanks!