Every year millions of people world-wide cut down a perfectly good conifer and welcome it into their home for Christmas. There is a lot of information out there on issues from the ecological impact of using a live vs artificial tree to how to keep your tree looking “fresh” the longest. Here’s a quick  look at the science of Christmas trees!

Am I doing the right thing?

Many argue an artificial tree is better for the environment as you’re not cutting down a living tree; however, artificial trees need to be manufactured (usually using plastics and metal) which comes with a completely different host of environmental issues. To make a positive impact on the environment, you’ll need to use the same tree for at least 8 years, and maybe as long as 20 years in order to offset the environmental impact of building and transporting an artificial tree.

In some places (cities, or areas with no local tree farms), an artificial tree makes good sense, despite your grandmother’s disapproval of not having a “real” tree.

The best place to get a tree is at a tree farm. If you don’t have one anywhere near your house, it may be time to make an 8-20 year commitment to an artificial tree. If you are lucky enough to live with a tree farm near by, environmentally speaking, a real tree is the way to go. We all know that trees are good for the environment: eating up carbon dioxide and producing oxygen all the while providing a habitat for all sorts of cute critters. By supporting a sustainably managed tree farm, you can minimize your impact on the environment and still get a great natural tree.

Is it really still “alive” once I cut it down?

When a Christmas tree is cut down, the tree itself is still technically alive as long as it can perform respiration. No, plants don’t breathe, in this case, we are talking about metabolic respiration, which is turning glucose into into energy within the cells. All plants and animals perform aerobic respiration, which uses oxygen to extract energy from the glucose. Once you cut down a tree, this aerobic respiration can continue for days, weeks, or even months – but it all depends on the tree, the conditions it is exposed to, and the care it is given. But the  the tree is ultimately doomed without its roots.

Fun Fact: Many Christmas tree farms use a “stumpculture” technique to regrow their trees. Customers are asked to cut the tree leaving the lowest 1-2 rows of branches on the stump. This allows the root system to continue to live; and eventually, one of the remaining branches will form a new tree. In this way, you never actually kill a tree when you cut your Christmas tree down, though you do set it back 8-9 years in its growth.

Choosing the right tree

First and foremost, select a healthy tree. Be on the look for dry, brown, or dead sections in trees as you shop. This is a sure sign that the tree is sick. Look deep into the tree for bug infestations – no one wants a thousand bugs hatching out on Christmas morning!

After narrowing down the selection to the fittest trees, there are two critical factors to look for increase the odds of longevity: freshness and selecting the right type of tree.

The best way to guarantee a “fresh” tree is to play lumberjack and cut down your own tree or purchase one from a “select-your-own” farm where the staff does the cutting for you. This minimizes the time between cutting the tree down and getting it into water back at your home. If there are no cut your own tree farms near you, make sure you ask the local pre-cut tree salesman how long ago their trees were cut down and pick the freshest option.

The type of tree is also important:

Trees that hold their needles well: Concolor fir, Douglas fir, Balsam fir, Frasier fir, Nordmann fir, Nobel fir, Canaan fir, Grand fir, Scotch pine, Red pine, White pine, Virginia pine.

Trees that don’t hold their needles well: Blue spruce, White spruce, Colorado spruce, Norwegian spruce, Eastern red cedar, Atlantic white cedar.

You’ll notice a pattern here: firs and pines are good at holding their needles. If you get a fresh, healthy tree and keep it properly watered, these should last for a month or possibly longer. Spruces and cedars will be making a mess of you home in 2-3 weeks if you happen to select one of those.

Preparing the tree

The key to a long “life” after cutting down a tree to hydration. When trees run out of water, they can’t perform respiration, and they stop living, turn brown and drop their needles all over your house. So try to minimize water loss while providing the tree with all the water it needs.

After you have picked a fresh tree and cut it down, set up ASAP. Don’t forget to cover the tree during the trip home to minimize exposure to the elements and help prevent moisture loss.

Even though you just cut your tree down, you’ll still want to cut at least an additional 1/2 inch off of the bottom of the tree before you put it in water. This removes the originally damaged stump of the tree, which has already started to clot with tree sap (think “sap scab”); sap, once hardened, will prevent water from getting into the tree.

Water, water, water…

Don’t let your tree dry out! Keep the level of water above the bottom of your tree stump at all times. Maybe set a daily alarm to remind yourself to water the tree? As long as it is in water, your tree has a fighting chance – and it will prevent the “sap scab.”

What about those internet tips that says I should add aspirin, vodka, sugar, bleach, a penny, etc. to the water of my tree?

DO NOT DO THIS. This is a case of bad science on the internet; and in the case of bleach, it will expedite your tree’s demise.

What about hot water to help “dissolve” the sap? Nope. Just cut off the end of the tree with the sap on it and you are good to go. Pure, room temperature water is all the tree needs.

Location, Location, Location

When considering where to put your tree, avoid direct sun, heating vents, and radiators. These can drive the precious moisture out of your tree.

So there you have it, a little bit of science to help ensure your tree will last through the entire holiday season.

Happy Holidays!