You Will Get 10 Seeds Sempervivum Species Mixed Hens & Chicks Hardy. This great popular perennial succulent forms small rosettes of foliage, and they can spread fairly rapidly to form a ground cover, even in dry areas or in poor soils.. They are hardy to at least USDA zone 4, and possibly colder.. These plants would make excellent additions to your rare plant collection, or just make a unique statement in your yard.