Cedar

Fertilizing

During the growing season, apply liquid fertilizer every two weeks or organic fertilizer every 4-6 weeks. Cedars can handle aggressive fertilization if you're prepared for vigorous growth and increased pruning needs. For a more manageable growth rate, maintain moderate to light fertilization, which will require pruning only once per year.

Keep in mind that fertilizing levels directly impact growth patterns - higher nitrogen promotes robust growth, while moderate feeding allows for easier maintenance. The balance between fertilization and pruning is especially important for maintaining the desired shape and health of your cedar bonsai.

Placement

Cedars require full sun exposure throughout spring, fall, and winter months for optimal growth. However, during summer when temperatures exceed 85°F (29°C), protect the tree with 30% shade cloth or provide morning sun with dappled afternoon shade. Young plants are particularly sensitive and need extra protection.

While cedars are generally hardy, they can suffer in extreme conditions. Protect from cold winter winds and freezing temperatures below 15°F (-10°C). The confined environment of a bonsai pot makes roots more vulnerable to temperature extremes than trees growing in the ground. A cold frame or unheated greenhouse provides ideal winter protection while maintaining necessary light exposure.

Pruning

Time pruning carefully throughout the growing season for optimal results. For structural styling, prune in early spring before the growth flush or in early fall. Allow the tree to deplete energy through late spring and early summer, then perform refinement pruning in mid to late summer (July-August) before interior foliage shedding occurs.

When refining, cut back elongated shoots to secondary or tertiary internodes to control fall growth and resource allocation. This single pruning session should maintain the tree's shape while managing energy distribution. The Cedrus is known for slow-healing wounds, so consider creating deadwood features like jin or shari rather than leaving visible cut marks. Young branches can be wired while flexible, but protect sensitive bark and use guy wires for older, brittle branches.

Repotting

Repot younger trees every 2-3 years and mature specimens every 3-4 years in early spring before new buds open or in early fall. Use well-draining soil with particles between 2-6mm, ideally a mix of Akadama, pumice, and lava rock in ratios of either 3:1:1 or 2:1:1.

Watch for winter foliage colors to fade and green growth to emerge before repotting. While cedars have durable root systems, avoid aggressive root pruning. Timing is crucial - repot as the tree transitions from winter dormancy to spring growth, but before soft new tips appear. This allows for optimal recovery and establishment in the new soil.

Watering

Maintain consistent moisture without overwatering, as cedars are susceptible to root rot. Allow the soil to dry slightly between waterings but never completely dry out. During the growing season, check water needs daily and adjust based on weather conditions.

Winter watering requires special attention - reduce frequency but ensure the rootball doesn't stay too wet, as this increases frost damage risk. Misting can help maintain humidity, particularly after repotting. For best results, use slightly acidic to neutral water (pH 5.5-7.0), preferably rainwater if your tap water is highly calcareous.

References

Bonsai Empire - Cedar Care Guide Bonsai Mirai - Western Red Cedar Guide Bonsai Empire - Japanese Cedar Guide