
Cut Christmas trees are the epitome of cut foliage. They grow on farms until harvest, like most other cut foliage. They then beautify homes and other interior spaces for Christmas. Ultimately, they become compost or green waste. Live Christmas trees are very different. They also grow on farms, and beautify interior spaces, but are living, evergreen conifers.
They are supposed to be the more sustainable option. Ideally, some live Christmas trees function as such for multiple years. A few are actually appropriate to home gardens when they grow too big to bring in. Realistically though, most live Christmas trees grow too fast and too large. Some actually become more of an environmental detriment than an asset.
Furthermore, live Christmas trees are actually less sustainable than cut Christmas trees. Cut Christmas trees grow on plantations where they need merely irrigation and fertilizer. Live Christmas trees require plastic pots, synthetic growing medium and more fertilizers. They only become sustainable after several years of reliable service as Christmas trees.
Among live Christmas trees, the more expensive sorts are typically the most sustainable. Various spruces grow slowly enough to remain potted and symmetrical for several years. They are more expensive because they take so long to grow to marketable size. As they outgrow their pots, most are proportionate to home gardens. Few grow as big shrubbery.
A few compact cultivars of fir and even pine are about as sustainable as spruces. Lemon cypress, Eastern red cedar and arborvitae are more conducive to shearing. Even as they grow faster, they can remain confined to pots for quite a few years. Afterwards, they might fit well into a garden. If not, they can be given to neighbors who can accommodate them.
Cheap, overly common and pre-decorated live Christmas trees are the least sustainable. Almost all are Italian stone pine or Canary Island pine. A few might be Aleppo pine. They may be pretty while new, but do not perform well for long as potted plants. However, they grow much too large for compact home gardens. Their long term options are very limited. Big trees require big landscapes.