Winter Burn on a Bonsai Juniper

Contributing Factors

• Winter burn occurs when the soil surrounding bonsai juniper freezes, while intense winter sun and wind cause excessive foliage water loss. The bonsai is often unable to keep pace with this troublesome combination of low temperatures, freezing winds and harsh sunlight. As a result, its needles dry out and turn brown. Bonsai junipers left in open, non-sheltered locations on the west and south sides of structures during freezing temperatures are highly at risk for developing winter burn.

Winter Storage

• Juniper bonsai are cold-hardy plants that will survive in very cold temperatures once they are fully dormant. However, they do not withstand negative temperatures as well as plants in soil because their above-ground container lacks the heat-sinking, insulating ability of ground soil. For best results, protect your juniper bonsai from very cold temperatures and strong fluctuations in the weather. Consider temporarily storing bonsai in a greenhouse, unheated shed or garage.

Other Protective Measures

• Wooden boxes with styrofoam insulation will provide a higher degree of protection and more constant temperatures than typical bonsai pots. Consider covering exposed soil with sphagnum peat moss mixed with perlite for additional warmth. Alternatively, you may bury your bonsai in well-drained soil, up to the lowest branch of the plant. You may also loosely wrap visible portions of the bonsai in burlap. Use twine to hold the burlap together and in place. Leave an opening at the top for air circulation.

Winter Burn Tips

• In general, evergreens transpire more than deciduous plants during the winter. While temperatures are above freezing, water your bonsai juniper frequently and deeply. Don't be too concerned if you notice some winter burn on plants. With proper care, winter-burned bonsai juniper will eventually rebound. Wait for the return of consistently warm temperatures before pruning back dead branches to living tissue. Often, branches with brown needles are still alive and will send out new shoots in the spring if given the opportunity. In the meantime, you can shake off brown needles by carefully brushing them off by hand or with a broom. Fertilize the plant well and water it thoroughly during the following spring.