Good morning Judy.
There are a few reasons the rosette can have a bare stem. The main one is the older bottom leaves have died and they either fall off or are removed. This normal and does not hurt the plant since new leaves grow from the center of the rosette.
When planting I would plant the roots and a small part of the stalk leaving the rosette sitting a bit high. Then fill in under the rosette with chicken grit or small gravel of some type.
I hope this is helpful.
