The C. acaule are rhizomes and not bulbs. Best to individually pot them. Do not overpot. Got any freshwater sand? Any pine needles that you can cut up? I would not use bark apart from some oak bark sparingly. Styrafoam should be broken down to gravel size. You will need to use either R/O water or distilled water. The water should be slightly acidic. And give plenty of dappled light. Do not let sit in a bowl of water. Water heavy after potting up and then at weekly intervals unless the pot feels too light. Presume these will be kept outside and that your winters are in the mid 30s F for 3-4 months.