Seems each person has their favorite mix. For Sempervivum they really want something that drains fast and doesn't compact and hold water.
For me I use Happy Frog. This is the mix I use.
http://foxfarmfertilizer.com/i...
I mix with pumice, about 3/4 potting mix and 1/4 pumice. This can vary.
If I am planting in my raised beds, which is a mix of forest compost, sand and chicken grit. After planting I top dress with chicken grit.
Others will come along soon and give you their recipe.
Just found this article that Chris did. Has a number of different recipes. : )
http://garden.org/ideas/view/g...
