Well, it’s that time of year again (yes… I’m rolling my eyes!) No, not the time of Rudolph or Frosty or even the biblical reason for the season. Not even time for artificially cinnamon-scented pine cones. Nope. Not that at all. But where we find ourselves this week is right smack in the middle of the annual debate about how best to delay the eventual point where your Christmas tree starts to deposit all its needles into your carpets, wool socks, cold air return vents and your golden retriever’s impenetrable undercoat.
So let’s get down to the question of how best to supercharge our Christmas trees so their fresh, green needles last until we’re ready to take the whole thing down… you know… around Oaks day!
First off, let’s review what your garden variety Christmas tree goes through when it makes the transition from it’s Norman Rockwellian tree farm in far northern Vermont or Wisconsin… or New Jersey… to the corner of the living room.
Depending on whether you choose to buy a tree that’s 2 feet shorter or two feet taller than the ceiling the tree will live beneath, your average Christmas tree has probably been growing in its field location for anywhere from 6 to maybe 8 or 9 years. It’s been growing a top portion, minus a little shearing here and there. And it’s also been growing a substantial root system that is tasked with supplying water and nutrients to the growing tree.
Then somewhere around the middle of October, some enterprising tree grower wanders up to your happy little tree, and without so much as a kind word, a reassuring pat on the shoulder or even a tiny sacrificial prayer, fires up the chain saw and cuts away, forever separating the tree’s top from its roots.
Once your tree is cut at the tree farm there are really just two things you need it to do… and do them for as long as possible: stay green and hold onto its needles. You don’t need it to grow new branches, produce bright red fruit or solve cold fusion. You just need to it to keep it all together for a few weeks to get you through the season. And the way you do that is by keeping the tree as well-hydrated as possible. That’s it. Nothing more complicated than that.
Now as gardeners you know that maintaining good water relations in a plant involves two things: reducing water loss and helping the plant absorb more water. So let’s look at some strategies for both.
Reducing Water Loss
The conifers we typically use for Christmas trees are pretty darned good at water conservation. Their needles are constructed to reduce surface area – much more efficient than a maple or oak leaf. The needles are coated with a waxy resin that further reduces water loss. And once the needles experience even a modest bit of water stress, they close up the somata – those little openings in all leaves that let in CO2 to fuel photosynthesis. There’s not much we can do to improve on these processes. Mother Nature’s got us covered there.
What we can do, however, is keep our tree in the least stressful environment possible through its literal and figurative December days. That means the coolest temperatures and the highest humidity – exactly what we don’t have in our warm and dry homes.
Maximize Water Absorption
There are two overriding things that reduce water uptake in a cut tree (or cut flower, for that matter). Those two things are 1) bacteria growth and 2) air embolisms.
The bacteria thing is pretty straightforward. If you gunk up a tree’s plumbing with a massive ball of steaming bacteria (ever smell water from a week-old bouquet of cut flowers?) it doesn’t matter how much water you pour in the tree stand and all over the floor. If the tree’s plumbing is all clogged up, the water can’t go anywhere.
Then there’s the air embolism. What the heck is that?
When you cut a tree, or a rose or a daisy, the water in the trunk (stem) is under tension and shrinks away from the newly cut end. That’s why we recommend cutting your cut flower stems under water. Rather than sucking in an air bubble, the stem sucks in water that helps to retain a continuous column of water from cut stem end to leaf. Once you introduce an air bubble, it can be hard to re-establish that continuous column. Unfortunately, the way to solve this problem with a Christmas tree is to treat it like a rose and cut your tree’s trunk while the whole thing is under water. “Wait, uncle Bob. Let me take a deep breath and get under water while you hold the tree… Now hand me that chain saw…” Good luck with that one!
So you’re now sitting there thinking this whole real tree thing is getting way too complicated. There’s bacterial population curves, underwater tree base cutting, some weird needle stomata thingies… Maybe it’s just best to throw in the towel. Well don’t despair because the answer is coming… and it’s really pretty simple.
According to modern research (and I think this may actually go all the way back to some ancient letter to the Thessalonians… ) there are really only four things to do to prolong the life of your cut Christmas tree.
1- Buy early
Unless you’re cutting your own tree, most trees were cut weeks ago. The sooner you bring your tree home and take care of it, the better the result. Sitting out in the tree lot is not doing it any favors.
2- Fresh cut
It really does help to make a fresh cut at the base of your tree when you get it home and then place the base in a bucket of water. Cutting off about an inch or so will do it. I’ll let you decide if you want to attempt the Captain Nemo, underwater approach…
3- Keep it cool and watered
The longer you keep the tree out in the cool and humid air, the better. The quicker you get that cut trunk in water (and keep it in water!) The better.
4- Hold off on moving it inside
If you want a fresh tree looking good until New Year’s, best to wait until about the middle of December before bringing it inside.
That’s it. No corn syrup or Sprite in the tree stand water. That just encourages bacteria growth. No Aspirin, or Advil. That’s better for the post New Year’s hangover anyway. No vodka or gin or rum. And just stop right there with that bottle of bourbon… That’s just wrong on so many levels. Just plain water is best.
Now if I could just find my snorkel…
This article was originally submitted to the Courier Journal on November 29, 2022.