Coniferous Bonsai Species
Almost any conifer species can be grown as a bonsai. The cedar, taxus, juniper and pine families all have many subspecies and varieties to choose from. Japanese black pine, Shimpaku juniper, cypress, white cedar, spruce, Japanese white pine and larch are among the most beautiful when trained as bonsai.
Some species are more challenging than others. Pines are the most difficult because the growth pattern of their needles is much different than that of other conifers. They make beautiful bonsai but their structure must be carefully studied before training or pruning begins.
Japanese Black Pine
In the wild, this tree can grow to 40 feet or more. As a bonsai, its graceful, irregular shape is pyramidal. This is the most difficult of trees to train and is very slow to grow.
The tender foliage of this conifer is easy to work with. Despite its flexible branches and soft look, Shimpaku can withstand extremes of heat and cold.
Cypress trunks have a beautiful, weathered look and can be curved and trained over time. This bonsai tree is excellent when planted alone or in groups.
This tree is also excellent for planting in groups. It is especially popular with those who practice deadwood techniques. The wood and foliage of white cedar are highly aromatic.
Like most conifers with needles, spruce is difficult to train as bonsai but well worth the extra effort. Its small needles are prized by experienced enthusiasts.
Japanese White Pine
A striking, pyramidal shape makes white pine a dramatic bonsai subject. Its needles are a paler green that Japanese black pine with a grayish, cloudy cast. Its foliage is extremely dense.
Larch is the only deciduous tree in this list. Bright autumnal color followed by a dormant, defoliated period make this type of bonsai endlessly interesting to study.
Potting & Repotting
Soil for coniferous bonsai should be 70 percent organic material and 30 percent grit, allowing it to drain well while providing adequate nutrients. Bonsai soil can be bought premixed at garden centers to ensure the correct ratio.
Spring is the season for repotting coniferous bonsai. Watch for new buds to appear. After removing the tree from its old pot, examine the roots for signs of coiling or compression. If this is the case, trim the roots lightly to free them and stimulate new growth. After root pruning, fill a slightly larger pot with soil and transfer the tree.
Repot young conifers every year to keep the soil fresh and full of nutrients. For older trees, repotting every other year should suffice. As the tree grows, use slightly larger pots to accommodate the growing root system.
Like most evergreens, conifers are winter-hardy and require periods of cold weather. Bonsai conifers are no exception, so do not try to grow them indoors. Conifers prefer full sun to partial shade, with plenty of water and humidity during the spring, summer and fall. At the end of growing season, it is common to see a few yellowed or dead needles. Simply brush them away as they occur, and remove dead needles from the surface soil in the pot before winter.
Coniferous bonsai may be kept slightly drier during the dormant season. In spring, when bright green buds appear at the branch tips, a light application of NPK fertilizer will help get the growing season underway. The buds will gradually become longer and taller, and are called “candles.”
Design & Shape
The best bonsai trees are those grown in a natural, flowing shape. Study the shape of a mature example of the species, noting its structure, number of branches and the vigor of its foliage. Most conifers have a pyramidal, conical form.
Of the infinite number of bonsai styles, conifers lend themselves best to the formal and informal upright styles. They may also be pruned in a dramatic slant or trained to cascade over the sides of the pot like a waterfall. No matter which style is chosen, remember that what is taken away will not regrow for months, if ever. This initial period of planning and study is extremely important.
Pruning & Training
Once the desired shape is visualized, it is time to prune the bonsai. Aggressive branch pruning should be done in late autumn and early winter when the tree is dormant. Leave a small stub when cutting branches close to the trunk so that new growth can invigorate the inner areas of the tree. Pinch off buds in spring with fingertips to stimulate thicker growth at the branch ends. A month later, clip off candles with sharp pruning scissors to control vertical growth.
Wiring coniferous bonsai is a technique that directs the tree’s vigor horizontally or downward, producing a dramatic effect. Anchor one end of the wire in the pot and wrap the other end around the branch or trunk with enough tension to move the branch slightly. Over time, increase the tension to achieve the desired angle of growth. Done gradually, wiring does not inhibit growth, merely directs it.
Never shear a bonsai to achieve shape. Doing so will result in browning of foliage tips, damage to needle groups and overall poor growth. It can even kill a young bonsai.
Pruning and training are the most challenging parts of bonsai. It is easy to make the mistake of doing too much rather than too little. The tendency to pinch buds at the ends of branches can result in an undesirable “poodle” look. Conversely, removing too many branches or too much foliage can damage the tree’s vitality. A conservative approach is often the most successful.