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 trip in just three or four days.

This incredible global system is the real reason we give roses on Valentine’s Day. Of course, roses have long been a symbol of love, sex and beauty, with soft petals and a scent that must have seemed outrageously sweet in the old days of open sewers, infrequent showers and no deodorant. When the prudish Victorians began using bouquets of flowers to telegraph their feelings to loved ones in a messaging system known as “floriography,” roses were cemented as a symbol of romantic affection.

But giving or getting a flower that typically blooms in the summer on Valentine’s Day, in the middle of the frigid month of February? That something so delicate can come from so far away, so cheaply, and at the moment when it’s just about to bloom – it’s truly a logistical miracle.

Decades ago, most flowers were grown relatively close to where consumers bought them, since they wilted so quickly after being picked. The Netherlands was home to a massive flower industry that supplied much of Europe, and fresh flowers were grown on farms around the U.S. But the invention of “cold chains” – shipping systems that keep goods at a constant temperature from the farm to the customer, and can preserve blooming flowers in a state of suspended animation – made it possible to move flower growing operations to lower-cost countries.

Today, the Netherlands still accounts for about half of the world’s cut flowers, especially the higher-quality blooms, according to Dutch financial company Rabobank. But beginning in the 1990s, production began to shift to mega farms in warmer countries with low-cost labor. Colombia and Ecuador now supply the bulk of flowers bought in the U.S., while Ethiopia and Kenya provide many for Europe. Industries have grown in Malaysia, Zimbabwe, India, Mexico and China, as well.

On the Tuesday before Valentine’s Day, 500 million Colombian flowers were estimated to reach the U.S. market, arriving on about 30 flights per day from Bogota to Miami. You might wonder why Colombia plays such a big role: It’s partly because the U.S. agreed to lift import duties on Colombian flowers to help offer alternate job opportunities to the drug trade. The U.S. imported 65 percent of its cut flowers from Colombia in 2013, up from 55 percent in 2003, according to Rabobank.

Part of the reason that roses are so widely available in the U.S. is that they are hardy enough to survive being shipped from these countries – as are carnations. “Many other flowers cannot be cheaply transported from far away,” says Cindy van Rijswick, a floriculture analyst with Rabobank. Tulips, lilies, irises and sunflowers are not so resilient, and are often grown in closer locations like California, or packed more loosely and with more care, which increases their shipping costs.

The stakes for having these roses travel halfway around the world and arrive just in time for Valentine’s Day – and in the perfect bloom -- are high. As an episode of Planet Money from last year points out, a dozen roses are almost twice the price on Valentine’s Day than they are on Feb. 15. Bungling the sale of roses at Valentine's Day can easily put a florist out of business.

But to warrant that high price, a rose needs to be coaxed into blooming at just the right time. By controlling the temperature, growers can speed up or slow down the blooming of the roses by about four days, but that’s it, according to the Planet Money podcast. If millions of roses bloom at the wrong time – just before or just after Valentine’s Day, as they do every few years – most will just be thrown away.

Given this risk, the challenge of global coordination, and the thousands of frequent flier miles that your Valentine’s Day roses accumulate, it’s a wonder that they are sold so cheaply. Online, a dozen roses can go for as little as $20 or $30.

But some argue that low price doesn’t reflect the real costs of growing the flowers.

Mega farms in South America mostly employ women, often for long hours and low pay, including unpaid overtime. Some have been accused of using child labor. The work can result in repetitive stress injuries and exposure to pesticides and herbicides, including known carcinogens.

The farms suck up local water and leave behind toxic chemical residues. The U.S. Department of Agriculture checks imported flowers for pests, but not for pesticide levels – incentivizing the use of massive doses of the stuff. Flowers can have 50 times the level of certain pesticides found in food (whatever you do, don’t eat commercially grown flowers.)

Independent certification programs have sprung up in response, such as Fair Trade flowers and VeriFlora. And some local producers have begun supplying premium, niche and organic products, says van Rijswick. “The trend towards local sourcing is not only a trend in the food sector but also in flowers.”

But locally sourced or organic flowers are still the exception. UPS has said it expects to deliver 100 million flowers this Valentine’s Day -- about 9 million pounds of bouquets, enough to fill 70 Boeing 767s – and that most of those flowers would come from Latin America.

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