Bonsai is the ancient Japanese art form of growing ornamental miniature or artificially dwarfed trees in containers using cultivation techniques to mimic the shape and scale of full-sized trees.
Juniper trees are especially popular choices in bonsai due to their ease of care, variable form, and gorgeous foliage. Junipers have a naturally compact growth habit which makes them well-suited to bonsai growing techniques, and relatively young juniper bonsai can look well-established without much effort.
Since some juniper species are low-lying ground cover shrubs, they also make fantastic cascading bonsai due to their natural downward growth habit.
|Botanical Name||Juniperus Bonsai|
|Common Name||Juniper Bonsai|
|Plant Type||Evergreen tree|
|Mature Size||60 - 80 inches (or as desired)|
|Sun Exposure||Full sun|
|Soil Type||Well-draining, bonsai soil|
|Soil pH||5.5 - 6.5|
|Flower Color||Blue, berry-like|
|Native Area||Europe, Asia, North America|
How to Grow Juniper Bonsai
Generally, juniper bonsai trees are easy to care for and thrive on neglect. They make perfect beginner bonsai trees for inexperienced growers as they are forgiving, easily shaped, and well-suited to bonsai growing techniques.
As with most species well-suited to bonsai, juniper trees take well to wiring, although it should be done slowly and carefully. Wiring is the practice of wrapping a wire around the branches of the bonsai tree in order to bend and reposition to achieve the desired shape. It is best to wire a juniper bonsai throughout the winter months when the tree is dormant. Once the branches have set in their new shape, carefully remove the wire with wire cutters so as to not damage the tree.
There are two main categories of juniper trees - trees with scale-like foliage and trees with needle-like foliage. Identifying which type of juniper bonsai you have will help to determine how to care for it properly.
Juniper trees with scale-like foliage include the Chinese juniper and the California juniper, while juniper trees with needle-like foliage include the Japanese needle juniper, green mound juniper, and the common juniper.
Juniper bonsai require bright, direct sunlight for the majority of the day. For this reason, juniper bonsai are best-suited to being grown outdoors year-round.
Use a commercially available bonsai soil mix for juniper trees for the best results. Bonsai soil mixes are well-draining, allowing both air and water to reach the roots, and are typically a combination of akadama (clay granulate from Japan), organic potting compost, pumice, and fine gravel/grit. They can be found at most garden centers or plant stores, or online from speciality bonsai retailers.
As with most bonsai, juniper bonsai require regular watering in order to keep the soil consistently moist. However, they cannot tolerate being waterlogged.
As a general rule, allow the soil to dry slightly between waterings, avoid letting it dry out completely, and then water deeply. Ensuring that the bonsai has adequate drainage is imperative in preventing the soil from becoming waterlogged.
Temperature and Humidity
Juniper bonsai trees should be grown outdoors year-round and cannot tolerate growing indoors. They are hardy, frost-tolerant trees that can withstand temperatures as low as 10 degrees Fahrenheit without protection. When extreme winter temperatures dip below this, providing juniper bonsais with moderate protection from wind and frost will help them to overwinter outdoors.
Juniper bonsai appreciate regular feeding during the spring and fall months to promote strong growth. However, cut back on fertilizing during the summer months to give the tree a break.
Use slow-release organic fertilizer once a month during the growing season, or a liquid fertilizer every week when watering. If vigorous growth is desired, a nitrogen-rich fertilizer is recommended - but only in the spring months.
To avoid shocking the roots, don’t fertilize a juniper bonsai after it has been repotted for at least a month.
Varieties of Juniper for Bonsai
The Juniperus genus contains between 50-70 species of trees and low-lying shrubs. The most popular juniper varieties for bonsai include:
- Japanese garden juniper (Juniperus procumbens nana)
- Chinese juniper (Juniperus chinensis)
- Common juniper (Juniperus communis)
- California juniper (Juniperus californica)
- Japanese needle juniper (Juniperus ridiga)
Proper and regular pruning is essential to the aesthetic and health of a bonsai tree. For juniper bonsai, pinching back growth rather than cutting back is recommended as cutting can cause the surrounding needles to die off.
Juniper trees can withstand aggressive pruning well but keep in mind that they cannot bud again from any bare tree parts. Always leave some foliage on the branches to ensure ongoing growth. It is best to prune juniper bonsai in the early spring and summer during their active growing period.
Potting and Repotting
In general, bonsai trees do not need to be repotted very often, including the juniper varieties.
Young trees can be repotted every two years at the most, and older trees can go as long as five years without being repotted.
For juniper bonsai, avoid heavy root pruning at the time of repotting to prevent shocking the plant.
Healthy juniper trees are quite resistant to pests and diseases, however, it is a good idea to keep an eye out for several common juniper pests/diseases. Watch for signs of spider mites, juniper scale, juniper aphids, juniper needle miners, as well as juniper webworms.
Regularly thinning out the foliage pads will help to decrease the likelihood of pest infestation as dense foliage pads provide the ideal environment for them. Certain species of juniper trees are also susceptible to fungal rust diseases.