How you plant succulents and cacti depends on how they grow. Cactus potting soil mixes are the best. The other option is to leave them as they are. Let the water reach the roots and give the plant a drink. You don't have to worry about losing your Tillandsia collection because healthy air plants can make multiple offsets at the same time. Once you've collected your cuttings, you'll need to leave them in the open air for a few days before planting cactus. I have my Aeonium arbutum 'Zwartkop’ outdoors all year.