Perhaps give it the tree treatment:

http://www.flyertalk.com/forum/delta...ree-delta.html

Trees (wedding gowns) need to be adequately packaged with the root ball or cut base and all branches wrapped and secured using a burlap-type material.
• If you are traveling into Hawaii and checking a Christmas tree/wedding dress as baggage, you must include it on your declaration form and the tree must pass agricultural inspection.