Juniper Bonsai Care: Outdoors, Sun, Watering and Winter

A juniper bonsai belongs outdoors in full sun with good drainage and good air circulation, watered when the soil is dry and protected through winter. Chicago Botanic Garden says that because junipers, whether bonsai or not, are hardy woody plants, they need to be grown outdoors. It describes bonsai as small specimens of regular trees or shrubs trained in pots to grow into beautiful shapes. Much of the advice below comes from Chicago Botanic Garden, a Chicago-area source, so adapt the winter dates to your own climate.

Sun

Full sun, good air circulation, good drainage

Origin

Asia

Container friendly

Yes

Where

Outdoors; junipers are hardy woody plants

Soil

Bonsai soil; standard potting mix can hold too much moisture

Water

When the soil is dry

Winter

Protected spot near the house, shredded mulch, off concrete (Chicago Botanic Garden)

Pruning

Larger cuts in spring; seal cuts with cut paste

Why a juniper bonsai stays outside

This is the main difference from a ficus bonsai. Chicago Botanic Garden says junipers need to be grown outdoors.

Sun, soil and drainage

Chicago Botanic Garden says junipers must have full sun, good air circulation and good drainage, and Clemson says they require full sun and well-drained soil. For the pot, Chicago Botanic Garden says standard potting mix can hold too much moisture for many species, so use bonsai soil.

Watering

Chicago Botanic Garden’s rule is to water when the soil is dry. Its warning runs in both directions: a tree that is bone dry or standing in water is a concern.

Pruning

Clemson says pruning is necessary to maintain form. Chicago Botanic Garden says it saves larger cuts for spring, when it is safer, rather than making them before winter, and covers all cuts with cut paste to seal the wound and prevent disease and damage to the branch.

Feeding for winter

Chicago Botanic Garden’s general guidance for hardy bonsai, including evergreens, is to stop nitrogen in late summer to early fall and switch to a feed higher in phosphorus and potassium to strengthen the roots.

Winter care

Chicago Botanic Garden’s winter plan for a juniper bonsai is a Chicago-area plan, so adjust the timing for your region.

1. Begin winterizing around Thanksgiving. Place the tree in a window well or another protected spot close to the house and cover it with shredded mulch (Chicago Botanic Garden).
2. Keep it off concrete. Do not place it on a concrete slab, which conducts cold directly to the roots (Chicago Botanic Garden).
3. Protect the pot. Chicago Botanic Garden says to protect the roots by packing mulch around the tree pots.
4. Consider an anti-desiccant. Some bonsai gardeners spray evergreens with an anti-desiccant to help prevent winter burning (Chicago Botanic Garden).
5. Reintroduce it to the weather in spring. As the warmer days of March approach, Chicago Botanic Garden says to put the plant outside for an hour or two each day.

Chicago Botanic Garden also says to prepare hardy bonsai long before winter and to protect trees from wind.

A juniper bonsai through the year

Problems to watch

Grow these next

A juniper is the evergreen of the group. Compare it with the Chinese elm bonsai guide, the trident maple bonsai guide, and, for a tropical tree that lives indoors in winter, the ficus bonsai guide. All of them are gathered in our bonsai section.