Dan Gill / LSU AgCenter Horticulturist
When it comes to Christmas trees, you have two basic choices: living or artificial. Although artificial trees have their place, and manufacturers are producing some startlingly realistic versions, I’m going to focus on the living types, as you would expect in a gardening column.
Living Christmas trees can be further divided into those that are cut and those growing in pots. Let’s start off with cut trees.
Stayin’ alive
Cut Christmas trees are still alive when you purchase them. Having their roots cut away when they are harvested will eventually kill them, of course. But it’s our job to keep them on life support and in good shape for as long as possible.
Life support means keeping water moving into the tree. A tree growing in the ground uses its roots to absorb the water it needs from the soil. When the roots are cut away, the surface of the cut trunk can still absorb water for the tree if it is put in water. A Christmas tree is like a giant cut flower, and we take care of it much the same way.
First, you must make sure the base of the trunk can absorb water as efficiently as possible. To ensure this, it’s best to recut the base of the tree trunk when you get it home and immediately put it into a large bucket of warm water. If the cut end of the trunk is exposed to the air for a period of time before you put it in water, the cut surface can become blocked and not absorb water as efficiently.
Most Christmas trees are harvested well in advance of being sold and have become somewhat dehydrated. (Trees that are harvested at local tree farms are the exception.) To rehydrate your tree, leave it in the big bucket of water outside in a shady location for a few days after you bring it home. Replenish the water as necessary — they can drink a lot the first few days. You can even spray it down with water once or twice as long as you allow it to dry before you bring it indoors.
Once inside, place the tree immediately into a stand with a generous water reservoir. Check the tree stand every day without fail, and add more water as necessary. Tree preservatives may be used but are not nearly as important as simply keeping the reservoir full.
Heat causes a tree to dry out faster. Turn on the lights only when necessary. And locate your tree away from heat sources like fireplaces, hot air vents and space heaters.
I will survive
Potted living Christmas trees still have their roots and will survive beyond the holidays. After Christmas, these trees or plants are often planted into the ground, where they will grow and become part of the landscape. Or they may continue as container plants to be used as a Christmas tree again in the future.
Because these trees will not be discarded after the holidays like cut trees, particular care should be taken to keep them as healthy as possible while on display. The plants we usually use as potted Christmas trees are not well adapted to indoor conditions, so we keep them indoors for as short a time as possible. Generally, limit the time indoors to no more than about two weeks.
Place the plant in front of a window where it can get natural light. Check the soil and add water when it feels dry when you stick your finger in it. If the pot is covered with decorative foil or plastic, it will hold excess water and keep the soil too wet. You should either punch holes in the covering to allow excess water to drain into a saucer or remove a smaller plant from the cover, add water, allow it to drain and then replace the cover.
Too much warmth is an issue for most of these trees. Place the potted Christmas tree away from heat sources such as heaters and warm air vents. It is best not to put lights on potted Christmas trees. Also, make sure the ornaments you use are not so heavy that they damage the branches.
After Christmas, either continue to grow the plant in its container outside or plant it into the ground outside. Many of the plants used for potted Christmas trees are hardy and can be planted in late December or January. The exception is the Norfolk Island pine. This tropical plant cannot tolerate freezes and should be kept inside in a sunny window over winter.
If you plant a living Christmas tree in the ground, you need to know what growing conditions it prefers and how big it will grow. Ask about this at the nursery. Most of these plants will need a sunny, well-drained location. Pay careful attention to the mature size.
It is easy to plant a relatively small potted Christmas tree in a location where it may grow to be far too large over time.
Some of the plants at your local nursery that can be used as potted Christmas trees and then be added to your landscape include spruce pine, Eastern red cedar, junipers (like Blue Point and Sky Rocket), Arizona cypress, deodar cedar, Savannah holly and other hollies (nice red berries, but they are poisonous, so you should be careful if you have young children or pets), Italian stone pine and rosemary (both of these are commonly available sheared into a Christmas tree shape). Look around at the nursery when you are there, and you may see other suitable choices.