A bonsai spruce tree can be a challenge to care for because it takes a fair amount of skill to mold this tree, which prefers a cone-shape, into a wind-swept bonsai. The everyday variables that need to be controlled when you are caring for a spruce bonsai are light, temperature, and water. You will also need to periodically deal with pruning and wiring.
Dwarfed spruce trees require direct sunlight. The exception to this is that, in the summer months, the tree should be shaded from the most intense midday sun. This type of bonsai tree thrives in cooler climates but can withstand some fluctuation in temperature in the summer months.
Spruce bonsai trees require soil that is kept moist but never saturated. During the winter months, the spruce will need watering less often. In the spring and fall, the tree can be misted along with keeping the soil wet.
To maintain the health of a spruce bonsai in the contained growing environment, you will need to supplement the soil. Every few weeks a liquefied bonsai food supplement should be added to the soil. If this is not readily available, regular plant fertilizer can be used at one-half the recommended dose. You should discontinue fertilizing the soil during the hot summer months. To help maintain the plant's many biochemical processes, the soil should also be supplemented with chelated iron two or three times a year.
Bonsai trees are kept miniature by clipping back the roots, using wires to gradually bend the tree limbs into a pleasing shape and by carefully pruning the tree to manipulate growth. Root pruning is important in bonsai container plants to prevent root balls from forming and to increase the plant's health. A bonsai spruce should be root-pruned when the plant looks like it is no longer thriving and during a season when the plant will not experience unnecessary temperature stress. To root-prune a spruce bonsai, gently remove the tree from the container and clip some of the thickest roots. Finally, re-pot the tree using fresh soil to position the tree and then water the soil.
The shape of a bonsai tree is manipulated by wrapping the branches with wire and then bending the wire gently to hold the branch at the desired shape. Shifting of the branches should be done gradually, and the wire should be a gauge that will hold the branch in the shape but not weigh it down. Spruce should be reshaped with wire during late fall and early winter.
Pruning of a spruce bonsai is a delicate process that may take some practice. Some of the new growth on the spruce tree should be gently pinched by hand off of the branch rather than cut free. Some pruning can be done in the spring, but the majority of pruning care should be saved until fall.