Juniper (Juniperus chinensis) – Bonsai Care

Scientific / botanical name: Juniperus chinensis. Description: Junipers belong to the Cypress family. They are coniferous, ranging from low-growing shrubs to tall trees reaching 15–16 feet. Juniper wood has a rich red hue and its hardness makes it highly suitable for cabinetry. Junipers produce berries valued as spices and for flavoring gin, and also used in Scandinavian dishes.

Position: Grow in a spot receiving more than four hours of sunlight each day, in soil that tends toward dryness. Watering: Junipers prefer slightly dry soil but should not endure prolonged dryness. Water the plant well, allow proper drainage, then let the soil dry before watering again. Junipers need some humidity for optimal growth — mist the leaves regularly and/or use a humidity tray under the pot. Feeding: Feed with half-strength liquid fertilizer once a month in spring and fall; do not feed in summer, and do not fertilize immediately after repotting.

Leaf and branch pruning: Spring and summer are best for pruning. Pinch back new shoots once they reach about one inch; continue from spring until mid-September. To develop foliage pads, long shoots sticking out of the silhouette can be pinched or cut at the base with sharp scissors throughout the growth season. Do not trim the juniper like a hedge — removing all growing tips weakens the tree and cut needles turn brown. When foliage pads become too dense, thin them out at the base with sharp scissors. The juniper is a strong tree that withstands aggressive pruning, but it cannot bud from bare parts, so leave some foliage on every branch you want to keep alive.

Repotting & growing medium: A bonsai potting mix should generally be gravel, akadama and compost in a ratio of 2-1-1. Junipers grown in containers grow slower than in the ground. Trees under 10 years old should be repotted every two years; those older every three or four years, with root pruning at repotting. Ideally repot in early spring, when the tree is not under pressure to maintain full foliage and suffers less shock. Do not prune the roots too aggressively.

Wiring: Junipers take well to wiring, but take care not to damage the plant; always use wire cutters. Because wiring saps the plant's vigor, it is best to wait about three months after repotting before wiring.

Notes: The juniper is more inclined to thrive on neglect than on being pampered; it dislikes too much watering or feeding. Fertilizing roughly every three weeks: high-nitrogen fertilizer in spring, balanced in summer, low-nitrogen in fall; none in winter (but keep watering). Winter protection: protect the tree once temperatures drop below -10°C (14°F); some species turn a purplish brown as a frost-protection mechanism and green up again in spring.

Seasonal watering — Summer: water twice a day, morning and evening; avoid watering the leaves in strong hot sun (it burns them); don't water when the sun is too hot (the water in the container overheats and spoils the roots); before a long trip, water heavily and leave the bonsai somewhere cool out of sunlight with the container standing in a bucket of water so it can draw water from the bottom (helps it survive 2–3 days). Winter: water once or twice a week; don't water when it is freezing (frozen soil can kill the plant), especially early morning or midnight; always water in the daytime, never in the evening. Spring and Autumn: water once a day, only when the soil is dry, ideally around the same time each day.