Hi Gardenlady...No answer to your question yet?

I find it easiest on plants to mail with the dirt and rootball intact, or even still in their pots...plants I mail are normally container grown. And, most of the plants I buy are shipped with dirt on the roots, rootball then wrapped in plastic, entire plant layed diagonally on newspapers and rolled. (For potted plants, I add moistened shredded newspaper to the pot top to keep any soil in place, wrap the pot in saran, do the newspaper roll up, fold top end over loosely so as not to damage foliage, fold bottom over too.)

To ship bareroot, I think the procedure is normally to wash the roots clean of dirt, add moist sphagnum moss to keep roots from drying out, wrap in plastic but not covering the crown, then finally roll the plant in sheets of newspaper.

It's more expensive to ship with the dirt on the roots of course, added weight. No matter which way you go, use Priority Mail...the less time in transit, the happier the plants will be.

This time of year it probably won't hurt if you have used some plastic but often, in some locations and at some times, the part wrapped in plastic will get steamed setting in the back of the UPS or USPS truck. It is safer just to use several layers of newspaper wrapping. Try to avoid weekends if you can e.g. ship on Mondays.