The finer the vermiculite, the worse that problem. A prominent grower in the Northwest uses slightly moistened sand in five gallon containers. The tubers keep very well but develop sprouts and feeder roots earlier than those in coarse vermiculite. Also, sand is much, much heavier. Perlite is not a good medium, because it does not absorb excess moisture, and its dust is unhealthy to breathe.
Experienced growers warn against peat moss.
Dry peat moss tends to make tubers shrivel while moist peat moss tends to promote rot. Numerous growers use wood chips to store tubers, but some warn that wood chips leach moisture from roots. Specify the higher quality wood chips that are supposed to be dust free. Dipping tubers in paraffin wax was fairly popular in the Northwest several years ago. Tubers dipped in wax tend to be very slow to develop eyes.