Americans who give or get roses on Valentine’s Day usually don’t think about where their flowers came from. But your roses may have traveled farther this year than you have.

A few days ago, the roses were likely 2,000 or 3,000 miles away, sitting in a Colombian greenhouse near the foothills of the Andes Mountains. The blooms probably traveled to Miami on a refrigerated plane, where some were poked and shaken by agricultural officials. Then they were sent on their (still refrigerated) way to flower shops around the U.S., arriving just in time for the holiday rush. Most roses make this tr...