Can a Juniper Bonsai Stay Out in the Cold?

Growth Description

• Juniper trees exhibit bright green needles and a low, cascading growth habit. Being a hardy species, they are ideal for bonsais because they grow even in tough soils and will bud in response to extensive pruning. They develop small feeder roots in a pot well. An important rule about the juniper bonsai is that it must be grown outside. In an indoor environment, the tree will not be able to respond appropriately to seasonal and temperature changes. Common juniper grows in a wide range of habitats, including dry, rocky, open terrain and can grow in alpine regions more than 9,000 feet in elevation.

Cold Tolerance

• As sun lovers, junipers should be placed outside for most of their life, but they need protection from extreme temperatures. When air temperature drops below freezing (32 degrees Fahrenheit) protect the roots with a deep layer of mulch or other covering. Some growers suggest plants can survive temperatures down to 10 or even as low as 0 degrees Fahrenheit. In any case, its important to protect the roots from freezing. Late frosts can damage young growth in the spring.

Dormancy

• A winter period of dormancy is essential for the juniper bonsai's health. This period, when the tree ceases growth, allows it to rest and rejuvenate in preparation for the upcoming growing season. Foliage changes color at this time, from blue-green to a bronze tone. Keep the bonsai in cool weather below 60 degrees in the winter months to ensure this occurs. It is difficult to force dormancy if junipers are left indoors. Wiring the tree (for repositioning) is best done during dormancy. The tree will weaken and ultimately die if it is kept from going dormant.

Ideal Growing Environment

• Junipers need an outdoor environment with plenty of bright sunlight and good air circulation to thrive. They also need to experience the seasonal and daily temperature fluctuations in order to survive. Kept indoors or in the shade, junipers may turn yellow from lack of sunlight. Junipers need loose, well-draining soil and plenty of nutrients to support their rapid growth.