Blue Spruce, Colorado Blue Spruce
Native to the S. W. North America this species occurs in many forms in the wild and in cultivation. It was introduced to Britain in about 1862. Recently it has become popular as a christmas tree. Blue spruce prefers slightly acid moist ground otherwise it can become prone to predation by aphids which spoil the colour and density of the mature needles and eventually cause defoliation.
Formal upright, Informal Upright, Slanting, Semi-cascade, Group planting, Saikei
Full sun, but needs shade from the midday sun in summer, or needle browning will result. These northern trees prefer cool temperatures, although small or young bonsai may need frost protection.
Spruces prefer moisture, but not waterlogged soil. Reduce watering in winter, but never allow the soil to dry out completely.
Every two weeks, spring-midautumn, using liquid bonsai food or half-strength general purpose fertilizer. In hot areas, discontinue feeding during the heat of summer. Apply a chelated iron supplement several times yearly.
Leaf and Branch Pruning:
New growth should be pinched, not clipped, several times in spring, when shoots are about 1 inch long, leaving 4-5 whorls of needles. Do major pruning in early fall. Never remove all needles.
Re-potting & Growing Medium:
In general, every 2-3 year in early to mid-spring, before new growth expands, or in early fall. Older specimens (+10 years) may be repotted every 5 years. Prune roots by a 1/3. Use fast-draining soil mix, 1 part Loam, 1 part peat, 1 part sand alternatively use 1 Part Akadama and 1 Part Fuji Grit or Pumice. Spruce, in general, need to keep a decent-sized root ball, and may need to be planted in a deep pot to achieve this. Protect from full sun for a few weeks after repotting.
Wire between late autumn and winter.