Nearly 30 million Christmas trees are sold in the U.S. each year, and while they appear in our homes only briefly, growing them is a full-time, year-round task.

Large-scale Christmas tree farms like Oregon's Noble Mountain Tree Farm are massive operations that employ thousands of workers.

They're designed to be efficient, and they rely on both old-fashioned human labor and modern technology.

While trees are planted and tended by hand at Noble Mountain, the harvesting process involves helicopters flown by skilled pilots whose speed and precision recently took the Internet by storm in a viral video.

How to grow a modern Christmas tree

Noble Tree is one of the world’s largest suppliers of Christmas trees, with 6 million trees planted on more than 5,000 acres. The farm grows a variety of trees, including Douglas firs, noble firs and Scotch pines.

Trees are planted by different methods at Noble Tree, depending on the terrain. On hills, workers plant individual seedlings by hand, while a simple planting machine is used on level ground.

Every tree is shaped by hand annually. Douglas firs are sheared by specially trained workers to achieve their classic shape while noble firs have their branches cultured so the trees will fill out.

"It takes extensive training for an individual to acquire the necessary experience to be able to look at a tree and proceed successfully with proper removal of branches," according to the Noble Tree website.

Workers also do frequent "top work" on the trees, cutting poorly formed tops and leaving the buds they think will form better ones.

It takes six to 10 years for a crop of trees to mature, and when they're ready for harvest, farm operators aim to get trees to consumers within hours of cutting them. This is where helicopters come into play.

At Noble Tree, helicopters lift freshly cut trees in loads of 20 and transport them to the farm's multiple staging areas. The trees are processed and loaded onto trucks or refrigerated vans, depending on the distance the trees must travel.

In the video below, watch helicopter pilot Dan Clark expertly deliver trees in poor visibility during Noble Tree’s 2008 harvest. Watch this video for a view of the process.

How green is that Christmas tree?

There’s long been a debate over whether real trees or fake ones are the more eco-friendly holiday choice, but plastic trees aside, can large-scale tree farming be sustainable?

The 1 million acres of Christmas trees growing in the United States produce enough oxygen for 18 million people per day, according to the Pacific Northwest Christmas Tree Association. And for every tree harvested, an estimated three new seedlings are planted.

Although tree-farming practices vary, it's in the grower's best interest to follow some sustainable practices. Trees need good soil to grow, so at Noble Tree water bars and cover crops are used to minimize soil erosion and runoff.

It's also common practice to rotate crops to allow soil to rest and to grind up stumps from old tree crops to add nutrients back to the soil.

Still, large-scale Christmas tree farming isn't entirely green. Fertilizers and pesticides are often used, and transporting trees by truck and helicopter is hardly eco-friendly.

If you want a more sustainably sourced tree, look for ones certified organic by the USDA or for a Certified Naturally Grown tree, which meets similar requirements. These trees are grown without synthetic pesticides or fertilizers, and they employ sustainable methods like composting and erosion control. can help you find an organic Christmas tree farm near you.

Laura Moss writes about a variety of topics with a focus on animals, science, language and culture. But she mostly writes about cats.

Follow the journey of a Christmas tree
Modern Christmas tree farms are often large-scale operations with thousands of employees — including helicopter pilots.