Of all the live Christmas trees available, the dwarf Alberta spruce is perhaps the most practical. It is a shrubby little tree with a big name, Picea glauca ‘Albertiana’ ‘Conica’. (‘Albertiana’ is typically omitted.) It is a dwarf cultivar of white spruce that grows very slowly. It takes many years to potentially get eight feet tall and half as wide at the base. Wild white spruce can grow a hundred feet tall.
The main disadvantage of the dwarf Alberta spruce as a live Christmas tree is the very dense foliage. It almost seems to be artificial. The small needles are only slightly bristly, and finely textured. Otherwise, dwarf Alberta spruce can remain potted as a Christmas tree for several years. It stays sufficiently compact to return to the home annually. It just does not want to be indoors for too long.
The strictly conical form of dwarf Alberta spruce is a distinctive feature in the garden. A pair of trees elegantly flanks a doorway or walkway. A row of evenly spaced trees instills formality to a linear border of bedding plants. Although they do not get too broad, they should have enough room to grow naturally. Pruning for confinement or clearance compromises their naturally symmetrical form.
By now most people have already acquired their Christmas trees. Some are live trees in containers. Some are artificial. Most are cut firs, pines, or alternatively, spruces, cedars, cypresses or even junipers. For at least the next two weeks, these trees dutifully maintain their healthy green vigor to brighten our homes with Christmas cheer.
Cut trees should have no problem lasting from the time they were originally cut through Christmas, as long as they get plenty of water. Artificial trees do not have much choice in the matter. Live trees are probably more reliable than cut trees are in regard to freshness, but can be more awkward to accommodate in the home, since they are more likely to leak excess water that can damage floors. If they they get a bit dry, live trees can also be sensitive to relatively dry and warm interior air after spending autumn out in cool and humid garden environments.
The main problem with living Christmas trees though, begins after Christmas. Spruces and other compact evergreens that can work as Christmas trees for several years need to be returned to the garden and maintained until next Christmas. Retired living Christmas trees, including those common, small trees that can be purchased with a few decorations already wired to their stems, eventually need to be planted out into the garden. Circling roots (that grow around the perimeter of a container in search of a way out) need to be severed so that they do not get constricted as they mature.
Unfortunately, with few exceptions, living Christmas trees mature into significant trees when they get the chance to grow. Those common, pre-decorated trees are most commonly juvenile Italian stone pine or Canary Island pine, which become very large trees. Because they seem so innocent as small potted trees, they often get planted in very awkward situations where they do not have enough space to grow without damaging nearby features.
Planting such a tree out in a forest is not practical, since it will not survive through the first year without supplemental watering. Their roots are just too confined to reach out for moisture. Even if such a tree could survive, it would not be an asset to the forest, since it would be an exotic (non-native) species.
Christmas trees are like vegetables. Really, they are like big vegetables that do not get eaten. They are grown on farms, and then harvested and sent off to consumers. Although they smell like a forest, and they are descendents of trees that naturally grow in the wild somewhere, there is nothing natural about their cultivation. In fact, most are grown a very long way from where their kind are from. Therefore, bringing a cut Christmas tree into the home takes nothing from the wild, and does not interfere with nature any more than eating vegetables does.
Firs, particularly Douglas fir, are the most popular of Christmas trees. Pines are probably the second most popular. Redwoods, spruces, cedars, cypresses or even Junipers can also work. They each have their own distinct color, texture and aroma. Healthy and well hydrated trees that continue to get watered as needed should have no problem lasting through Christmas. Ultimately though, cut Christmas trees are not good for much after Christmas, and eventually get composted or otherwise disposed of.
Living Christmas trees might seem like a better option to cut Christmas trees because they dispel any unfounded guilt associated with cut Christmas trees, and initially seem to be less disposable. The problem is that they have problems of their own. Simply purchasing one is a big expense. Even the big ones are smaller than cut trees, but much heavier and unwieldy. Contrary to popular belief, only a few types that grow slowly, such as some spruce, can actually live in a tub for more than one or two years, and even they can be finicky.
The main problem is where to plant a living Christmas tree when it outgrows its container. Conifers innately do not like to be confined for too long. Yet, in the ground, most grow into substantial trees. The common little Christmas trees that are already decorated are actually the worst since they are juvenile Italian stone pines or Canary Island pines, which grow big and fast. Potted trees can not be planted out in the wild because their confined roots need to be watered until new roots can disperse. Even if they could survive, non-native trees should not go into natural ecosystems.
There should be no guilt associated with a cut Christmas tree. They were stigmatized many years ago, when some people believed that they were harvested from forests, and more of them likely were back then. However, most of us now know that, except for a few that actually are harvested from the wild, Christmas trees are grown on farms like most other cut foliage or horticultural crops.
That is how Christmas trees get their nice Christmas tree form. Only spruce and a few types of firs grow so densely and symmetrically in the wild; and spruce are not commonly cut as Christmas trees. Almost all types of Christmas trees need to be pruned or shorn for density, symmetry and maybe even form. Most of the foliage for wreaths and garlands is likewise grown on foliage farms.
Contrary to popular belief, living Christmas trees are no more environmentally responsible than cut trees are. They are farm grown and artificially irrigated exotic (non-native) trees in vinyl cans filled with synthetic media (potting soil) and synthetic fertilizers. Just like cut trees, they need to be shorn unnaturally. Then, after all that effort, most die and get discarded after Christmas anyway.
Those that survive are usually more trouble than they are worth. Because they are exotic, they should not be planted out in the wild. Because their roots are confined, they would not survive without irrigation through the first year anyway. A few types that grow slowly and maintain density might stay potted and be brought in at Christmas for a few years, but that requires diligent maintenance.
The worst problem with living Christmas trees is that they often get planted into home gardens that can not accommodate them. Few people know what kind of tree their living Christmas tree is, or realize how big it can get. Some trees are Italian stone pines or Canary Island pines, which simply get too large. Even junipers, arborvitaes and smaller pines need adequate accommodations. Arborists can attest to damage caused by living Christmas trees in bad situations.