The cuttings I started this spring are now 3 feet tall in 3 gallon pots. I'm in Southern California (zone 9 b). I'd like to mail a tree to Boston for Christmas. Assuming it drops foliage by then, can I just ship it out bare root in December? Should the recipient immediately plant in 5 gallon pot and keep in basement until spring frost?

By the way, is it legal to send a tree from California to Massachusetts?

Yes, you can bare-root it after it gets dormant, pack it properly and ship. You don't have to ship it 3 ft long but can trim it a bit for shipping(it grows fast). The receiver can pot it in 3 or 5 gallon pot and keep it in cool dark place with temperature under 45F to avoid growth until spring. The receiver may choose to place it in a warm lighted place to let it green up and grow.

I knew that would be an easy question for somebody here. Thank you.

Good Stuff....Great Topic, What is the best packaging material for mailing dormant bare root trees, wet newspaper, moist newspaper (not to wet) wood chips...???
Make the wrap air tight or do the roots need a little bit of air...????   Been thinking about shipping back east to.

People have been using different things for covering the root ball such as moist shredded paper or  sphagnum moss etc. in a plastic bag. Then wrapping in couple of layers of paper for protection and insulation depending on the temperature during shipping days. Bubble envelopes work fine too.
Inform the person of expected receiving date if shipped in the cold of January and February in case it is left in the mail box or in front of the front door.

If you bare root it, ship it earlier, when weather is not freezing. Less likely to get damaged. You can force dormancy by removing the leaves, rather than waiting. Yes, pot it upon arrival.