It depends on the plant. Many plants and animals are not allowed in through U.S. customs. Even shells can cause you problems with the customs agents! Trust me I know!  The U.S.D.A won't allow certian plants on American soil. The laws were created to stop the import of agressive plants entering the country. Some states (Like California) have restrictions about what plants can be sold or delivered to them. I think it was too little, too late! Think Kudzu! HA!

Most plants sold in the airports have been approved for import. I think that Hawaii is more concerned about plants and animals entering their islands, than the ones exiting them. Hawaii is a state, they should know all of the rules about exportation of pants to the mainland. Except for some of the "Exotics" I.E. "Primo Kona Bud", I would expect that all palnts sold to tourists have already been approved for sale/import in the contenental U.S.

You grow Orchids? Cool! They are tough. I respect anyone that can grow them. Talk about a picky plant. All of the great ones are very hard to grow. Heck, I kill the Wal-Mart varieties! HA! I hope that I have been some help. Good Luck!

Del