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.
Pot plants are very different from common potted plants. Potted plants sustain healthy growth within pots or similar containers. They can range from small houseplants to small trees in big tubs out in the elements. Those that do not live for long in a particular pot before outgrowing it can continue to live in increasingly larger pots. They are considered to be sustainable, rather than temporary.
Pot plants, conversely, are generally expendable. They come into the home or office at their prime, but stay only as long as they continue to perform. For some, this may not be more than a month or so. They typically live their entire brief lifetimes within their original pots. Many endured forcing techniques that are difficult to recover from. Some are little more than uncut cut flowers with roots.
Most pot plants are seasonal. Most are seasonal at Christmas time. These include poinsettias, amaryllis, Christmas cactus, azaleas, hollies, cyclamen, rosemary (in conical ‘Christmas tree’ form) and live Christmas trees. Chrysanthemums were seasonal for autumn. Miniature roses will be in season for Saint Valentine’s Day. Easter lilies and hydrangeas will be seasonal in time for Easter.
Recovery from forcing techniques that are necessary to grow unnaturally showy pot plants is not impossible. It just might be difficult. That is why most poinsettias, Easter lilies and miniature roses rarely survive in the garden. Some pot plants, particularly azaleas and hydrangeas, are cultivars that excel as pot plants, but not in a garden. Christmas cactus and hollies are more likely to thrive.
Some types of live Christmas trees are likely to survive as well. That may not be an advantage. Dwarf Alberta spruce can remain potted as a live Christmas tree for several years, and then do well in the garden. Other spruces may remain potted for a few years, but then demand more space in the garden. Most other live Christmas trees either do not recover in the garden, or grow too large, such as Italian stone pine or Canary Island pine.
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.
Relative to other pines and evergreens that are commonly grown as living Christmas trees, the uncommon and even rare Austrian pine, Pinus nigra, would be a better option. If it gets planted too close to the home, as Christmas trees often do, it does not get big enough to cause major problems. Although much bigger in the wild, local trees may take decades to reach second story eaves.
The species is divided into two subspecie, which are each divided into three regional varieties, which is a fancy way of saying that individual trees may have distinct personalities. Generally, they resemble Japanese black pine, with similar irregular branch structure, but are more dense, and may get a few pendulous stems with age. The dark green needles are slightly shorter and stouter.
The Austrian pine was likely named as such when much of its natural range was still within the Austro-Hungarian Empire, which has since been subdivided into the countries east of the Adriatic Sea. Other larger parts of the range are in Turkey and Spain. Only a small colony lives within Austria, west of Vienna. Austrian pine likes full sun and warmth like it would get naturally back home.
After all the Christmas decorations get put away for next year, and the Christmas tree eventually gets undressed from all its ornaments, and retired to the compost pile or greenwaste, all the pretty seasonal potted plants remain. Some will bloom, or at least maintain their current bloom, for months. Some might eventually get planted out in the garden. Others might stay potted in the home.
Poinsettias are the epitome of seasonal potted plants for Christmas. Their flashy red bracts last a very long time, even after the tiny yellow flowers are gone. Some are pink, white, pale yellow, peachy, marbled or spotted. They can be grown as foliar houseplants, but will not likely bloom next Christmas. If protected from frost in the garden, they get tall and lanky, and bloom in January.
Christmas cactus is an excellent potted plant either indoors or out where protected from frost. The pendulous growth cascades nicely from a hanging pot. It blooms in phases, but does not stick to a tight schedule. Amaryllis should also stay potted only because it does not do well in the garden over winter. Foliage that develops after bloom will die back next autumn before bloom next winter.
Holly and azalea can be planted directly into the garden where appropriate. Azalea will probably look shabby until it gets new growth. Cyclamen is a perennial in the garden, but dies back over summer. It just might come back with a surprise in autumn. Paperwhite narcissus is perennial too, but exhausts its resources on bloom, so takes a year or more to recover before blooming again.
Small living Christmas trees are more variable than they seem. Rosemary can either be kept potted and shorn, or planted into the garden and allowed to grow wild or into another form. Dwarf Alberta spruce can likewise stay potted or get planted into the garden, but needs no shearing. Both rosemary and dwarf Alberta spruce will want larger pots as they grow. Italian stone pine and Canary Island pine grow into large shady trees, so should only be planted into spacious landscapes that can accommodate them.