By: Liz Froment

You can walk into your local supermarket on the coldest and grayest of days where you live and still get met with a splash of color. Fresh citrus—including oranges, lemons and grapefruit—can perk up your diet and provide a healthy dose of vitamins.

Citrus, which grow on trees, are harvested year-round in the U.S. and shipped all over the country—even when it's cold and dismal where you live.

If you've ever been interested in how citrus makes it from its sunny home to your supermarket, keep reading. We've got you covered.

First, a Little History

None of the most common citrus fruits, oranges, grapefruit and lemons are native to North America. However, they have been growing here for a while.

Experts believe citrus fruits originally come from Southeast Asia. Through trade, migration and exploration, citrus made its way around the world. First, citrus appeared in the Middle East and the Mediterranean region. Then the fruit arrived in the Americas when explorers brought it with them to the New World.

It just happened that Florida's sandy soil and warm weather was perfect for growing citrus. Florida first began producing oranges commercially in the mid-1800s. Today it's a $9 billion dollar industry.

The story isn't all that different in California, the other top citrus producer in the country. Here, estimates are that Spanish missionaries brought oranges with them in the mid-1700s, and by the mid-1800s, with the arrival of settlers from the East, commercial groves were in production.

Understanding Production

Where citrus grows matters because they are not cold-hardy plants. Most can't survive when the temperature dips below freezing for an extended period. That's one reason why an unexpected lengthy frost or cold snap can cost millions of dollars in damage to Florida and California's citrus production.

Currently, citrus makes a good showing on the list of the top 10 U.S. produced fruits. Oranges are third, behind only grapes and apples, with nearly four million tons produced each year. The U.S. also produces over 800 thousand tons of lemons, as well as mandarin oranges and tangerines, per year. Grapefruit is also on the list, with over half a million tons grown annually.

The citrus grown in the U.S. is used in a variety of ways. The fresh oranges you grab at the supermarket are only a tiny fraction of what's produced and used by consumers. In fact, the vast majority of Florida citrus is used for juice. About 87 percent of all citrus grown in Florida is used in canned, chilled or frozen concentrated juice.

How Citrus Grows in Cold Weather

Citrus trees are grown in groves in warm weather climates that also have stretches of rainfall after the summer heat. The heat is what gives citrus its sweetness. The longer the summer, the sweeter the orange. That's why Florida and Southern California are the most popular areas for growth in the U.S.; the climates meet these conditions perfectly.

In Florida alone, there are 74 million trees spread across more than half a million acres. The trees are usually planted in sunny spots in long rows, making for easier harvesting.

When it comes to growing citrus, it takes time. A tree will usually take about three years to become mature. Once it is, you'll get one harvest of fruit each year. The fruit takes anywhere between six and eight months to ripen.

When the fruit is ready for picking, it's done by hand. Workers handpick the fruit off the trees and load them into bags, which are taken for processing. The fruit that goes directly to the supermarket is taken to a packinghouse where it will be washed, packed and sent to the grocery store. Everything else is sent for processing for juice, and then, eventually, back to you at the supermarket.

So, that's how fresh citrus makes its way from the warm and sunny groves of Florida and California for you to enjoy in your homes.

Liz Froment is a content marketing writer and strategist with a focus towards insurance, real estate and finance.