MIAMI (AP) — While Valentine’s Day may not be known as a busy time for air travel, it’s a busy time at Miami International Airport, where many of the nation’s fresh cut flowers arrive from South America.

Around 90% of the roses and fresh cut flowers being sold for Valentine’s Day in the United States come through Miami, according to U.S. Customs and Border Patrol. They arrive on hundreds of flights into Miami on their journey to florists and supermarkets across the U.S. and Canada. That equates to some 18,000 tons of flowers passing through Miami.

“This season we transported around 460 million flowers from Ecuador and Colombia,” Diogo Elias, senior vice president of Avianca Cargo, said Monday during a news conference in Miami.

Among the most exported flowers this season by the airline were roses and carnations from Bogota; pompons, hydrangeas and chrysanthemums from Medellin; and roses, carnations and gypsophila from Quito, Avianca said in a statement.

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The Valentine season actually started in mid-January and ends Wednesday. During that three-week period, flowers arrived in Miami on some 300 flights, Elias said.

And that’s where U.S. Customs and Border Protection agriculture specialists come into play. At the airport, they check the bundles of flowers to prevent the introduction of potentially harmful plant, pest and foreign animal disease from entering the country.

Their job is to make sure the floral imports don’t contain the kinds of exotic pests and foreign animal diseases which have caused $120 billion annually in economic and environmental losses in the United States, said Danny Alonso, the airport’s port director.

It is a massive undertaking.

Through Feb. 8, agriculture specialists had processed about 832 million stems of cut flowers, inspected 75,000 cut flower sample boxes, and intercepted 1,100 plant pests, he said. During the same time last year, specialists processed more than 861 million stems of flowers, resulting in 932 plant pest interceptions

“It’s one of the most demanding times of the year for our staff here,” Alonso said.

And once the Valentine’s rush is over, everyone involved can take a quick breath before planning begins for the next big flower day in the United States — Mother’s Day in May.