Abies

A very large montane evergreen conifer of cool, moist European mountain forests, narrowly conical when young and reaching well over 100 feet (often 30 m and more) at maturity. Its signature is the foliage: flat, blunt, comb-arranged needles that are dark glossy green above and marked beneath with two chalky silvery-white bands, giving the 'silver' fir its name. Mature trees carry upright, barrel-shaped cones high in the crown that ripen and shatter on the tree rather than falling whole. Abies alba is native to the mountains of central and southern Europe - the Pyrenees, Alps, Apennines, Carpathians and Balkans (POWO, Kew) - and it carries that origin into the garden: it wants a cool, moist, sheltered climate and deep, well-drained soil, and it struggles with summer heat, drought, atmospheric pollution and late spring frosts. It is slow to establish and then long-lived, a forest-scale specimen for large, cool gardens and uplands rather than hot or urban sites.

Fraser fir (Abies fraseri) is an evergreen fir endemic to the high-elevation southern Appalachian Mountains of southwestern Virginia, western North Carolina, and eastern Tennessee, where it grows only on cool, moist, fog-drenched summits above roughly 4,000 feet. It is a modest-sized conifer, usually 30 to 50 feet tall with a narrow, spire-like crown, soft flattened dark-green needles with silvery-white undersides, and erect purple cones whose papery bracts curl back over the scales. It is best known as one of the most popular Christmas trees in North America, prized for its balsam fragrance, soft non-prickly needles, and excellent needle retention. The honest catch is that it is a true mountain plant: it needs cool summers, high humidity, and acidic, evenly moist but well-drained soil, and it does poorly in the heat and humidity of the lowland South, roughly anywhere below or south of USDA zone 7. Its wild stands are also in serious trouble - the introduced balsam woolly adelgid has killed the great majority of mature wild trees since the mid-20th century, and the species is assessed as Endangered.

Korean fir (Abies koreana) is a compact, slow-growing evergreen fir from the high mountains of southern South Korea, where it is confined to cool, misty summits, most famously Hallasan on Jeju Island. In gardens it makes a dense, neat, conical small tree, usually 15 to 30 feet over many years, with short broad needles that are dark green above and marked beneath with two vivid white bands, so the whole tree flashes silver when the wind turns the foliage. Its signature is the cones: erect, cylindrical, and an intense violet-blue when young, and unusually it bears them freely even on young plants only a few feet tall, which is why it is one of the most collected ornamental firs and holds the RHS Award of Garden Merit. The honest catch is that it is a true mountain conifer: it wants cool summers, steady moisture, and acidic, well-drained soil, and it resents heat, drought, and urban pollution, so it disappoints in hot lowland gardens south of about USDA zone 7. It is also Endangered in the wild, where warming is widely blamed for pushing its shrinking high-altitude stands, most visibly on Jeju, further up the mountains.

White fir (Abies concolor) is a large evergreen conifer of the mountains of the western United States and into northern Mexico, grown in gardens for its soft, blue-green needles and neat, narrowly pyramidal form. The needles are long for a fir - roughly 1 to 2.5 inches - flattened, blunt or slightly notched, and nearly the same pale blue-green on both surfaces, which is the meaning of the name concolor. Its real selling point is adaptability: it stands up to heat, drought, and urban conditions far better than most firs, which makes it one of the few worth trying in the Midwest and the drier interior West where other firs sulk. That tolerance has honest limits - it still does poorly in the heat and humidity south of USDA zone 7, it is slow-growing, and it breaks bud early enough that a late spring frost can scorch the soft new shoots. Grown as a specimen, a screen, and a long-needled Christmas tree, it is long-lived, reaching about 40 to 70 feet in cultivation and well over 100 feet in the wild.