"Real" and "fake" blue trees come in a large number of cultivars, more or less dwarf, which can be recommended for a small garden.
The dwarf Colorado spruce, Picea pungens 'Glauca Globosa' is commonly called the "dwarf blue fir". It is the most common cultivar, and certainly one of the best varieties for small gardens and container growing. It forms a nice compact ball, which evolves into a rounded pyramid that can reach 2 m high at 30 years. The average annual growth is 6 to 8 cm. The short and tight needles, prickly, keep a beautiful silver-blue color all year long. It has been cultivated since 1937.
Among the Picea pungens, there are other dwarf forms like 'Glauca Procumbens', totally spread out, to be cultivated with golden heather. It has been cultivated since 1910.
Picea pungens 'Prostrata' is a closely related cultivar that does not exceed 60 cm in height, but can spread over 2 m wide.
The white fir (Picea glauca) has given some dwarf and bluish forms like: Picea glauca 'Echniformis' which forms a spreading cousin of 50 cm high at adulthood, with greyish glaucous green needles. Picea glauca 'Sanders Blue' forms a cone of about 50 cm high at 15 years old, with very nice young blue shoots.
Collectors will remember some less common forms like Picea x mariorika 'Machala', a hybrid of Picea mariana and Picea omorika, which forms a compact rounded pyramid with a silvery blue sheen. It reaches barely 1 m in height and width when mature. It can be recognized by the two silvery white stripes on the back of its needles (like Picea omorika).
Among the true firs, the dwarf and blue forms are rarer.
Abies concolor 'Archer's Dwarf' is a slow-growing, glaucous American cultivar to be grown in rock gardens.
Abies concolor 'Compacta' with greyish steel blue needles is more common, characterized by an irregular silhouette. It can grow to over 2 m when fully grown. It has been cultivated since 1891.
Abies cephalonica 'Meyer's Dwarf' (or 'nana') grows horizontally. It is cultivated since 1963.
Abies lasiocarpa 'Compacta' (sometimes wrongly called Abies arizonica 'Compacta') forms a nice regular pyramid, very tight, of a beautiful bluish grey. It is over 2 m high when mature and resists well to drought, but does not appreciate limestone. It has been cultivated since 1927.
Abies magnifica 'Nana' is a rarity that forms an irregular stack of bluish swatches.
Abies pinsapo 'Horstmann Witches', takes a spreading, rather irregular form with a mixture of green and bluish branches.
Abies procera 'Blaue Hexe' is a very dwarf, tightly balled form from Germany, best grown in pots.
