Sugi
Cryptomeria japonica · Japanese CedarUSDA | Grow Zone
5-8Outdoors all year in zones 5 to 8. Anywhere colder, keep it as a houseplant. Protect it below 10°F.
- Light
- Full sun to partial shade
- Water
- Deeply once a week
- Humidity
- 40-60%
- Temperature
- 60-75°F
- Difficulty
- Intermediate
- Growth
- Moderate
- Mature size
- 40-60 ft tall
- Pets
- Non-toxic to pets
Cryptomeria japonica, commonly known as Japanese Cedar, is a majestic evergreen tree native to Japan. Valued for its attractive foliage and resilience, it makes a stunning addition to landscapes and gardens.
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Ideal temperature
60-75°F is where it grows fastest. Below 10°F cold damage starts.
Spacing and harvest
- Mature size
- 40-60 ft tall
- Plant apart
- 180-300 in
- Frost
- Hardy: survives frost
Everything it needs
9 essentials at a glance
Watering
Cryptomeria japonica prefers consistently moist soil, especially during its active growing season in spring and summer.
Water deeply once a week, allowing the top inch of soil to dry out between waterings. In the fall and winter, reduce watering to every two weeks or as needed, depending on rainfall. Signs of over-watering include yellowing leaves and root rot, while under-watering may cause browning leaf tips and stunted growth.
Light
This plant thrives in full sun to partial shade, ideally receiving at least 6 hours of direct sunlight daily.
It can tolerate some shade but may become leggy if not provided with enough light. Ideal placement includes areas with morning sun and afternoon shade, particularly in hotter climates.
Soil
Cryptomeria japonica prefers well-draining, loamy soil with a pH range of 5.0 to 6.5.
A mix of peat, pine bark, and perlite is recommended for potting. Good drainage is essential to prevent root rot, so ensure pots have drainage holes and avoid compacted soils.
Humidity
This plant prefers moderate humidity levels, ideally between 40-60%.
To increase humidity, mist the leaves regularly or place a humidifier nearby. Signs of humidity stress include browning leaf tips and excessive needle drop.
Temperature
Cryptomeria japonica thrives in temperatures ranging from 60-75°F (15-24°C) and is hardy in USDA zones 5-8.
It can tolerate brief periods of cold down to 10°F (-12°C) but may suffer in extreme heat above 90°F (32°C). Protect young plants from frost during winter.
Fertilizing
Use a balanced fertilizer with an NPK ratio of 10-10-10, applying it every 4-6 weeks during the growing season.
In fall, switch to a low-nitrogen fertilizer to prepare the plant for winter. Signs of nutrient deficiency include yellowing needles and stunted growth.
Pruning
Prune Cryptomeria japonica in late winter or early spring before new growth begins.
Use sharp, clean pruning shears to remove dead or damaged branches and to shape the tree. Light trimming can help maintain its form, while heavy pruning should be avoided as it can lead to unsightly growth.
Repotting
Repot every 2-3 years or when the roots become pot-bound.
Choose a pot that is 1-2 inches larger in diameter than the current one. Signs it needs repotting include roots growing out of the drainage holes or water pooling on the surface. Carefully remove the plant from its pot, trim any circling roots, and place it in fresh potting mix.
Propagation
Propagation can be achieved through semi-hardwood cuttings taken in late summer.
Cut 4-6 inch sections from healthy stems, remove lower leaves, and dip the cut end in rooting hormone. Plant in a well-draining potting mix and keep moist until roots develop, which may take several weeks. Alternatively, seeds can be collected and sown in spring.
When it's unhappy
Yellowing leaves
Why it happens
This can be caused by over-watering, nutrient deficiency, or poor drainage.
How to fix it
Check soil moisture and adjust watering frequency. Fertilize if nutrient deficiency is suspected.
Browning leaf tips
Why it happens
Browning tips may indicate under-watering or low humidity levels.
How to fix it
Increase watering frequency and humidity levels by misting or using a humidifier.
Root rot
Why it happens
Root rot is typically caused by over-watering or poorly draining soil.
How to fix it
Ensure proper drainage and reduce watering. If root rot is present, remove affected roots and repot in fresh soil.
Pest infestations
Why it happens
Common pests include aphids and spider mites, which can weaken the plant.
How to fix it
Inspect regularly and treat infestations with insecticidal soap or neem oil.
Needle drop
Why it happens
Needle drop can occur due to stress from environmental changes or pests.
How to fix it
Identify and address the stressor, whether it's watering, light, or pest management.
Care through the year
Spring
In spring, focus on watering regularly as the plant begins to actively grow. Fertilize with a balanced fertilizer to promote healthy growth.
Summer
During summer, ensure consistent moisture, especially in hot weather. Monitor for pests and increase humidity if necessary.
Fall
In fall, reduce watering frequency as the plant prepares for dormancy. Consider applying a low-nitrogen fertilizer to support root health.
Winter
In winter, protect young plants from frost and reduce watering to every two weeks. Ensure the plant is in a sheltered location to avoid cold drafts.
Toxicity & Safety
Cryptomeria japonica is considered non-toxic to pets and children. However, ingestion of large quantities may cause mild gastrointestinal upset. Always monitor pets around plants.
Good to know
Why are my Cryptomeria japonica leaves turning yellow?
Yellowing leaves can indicate over-watering or a nutrient deficiency. Check the soil moisture and consider fertilizing if necessary.
How often should I water my Japanese Cedar?
Water your Cryptomeria japonica deeply once a week during the growing season, allowing the top inch of soil to dry out between waterings.
What is the best soil for Cryptomeria japonica?
The best soil for Cryptomeria japonica is well-draining, loamy soil with a pH between 5.0 and 6.5. A mix of peat, pine bark, and perlite works well.
How do I propagate Cryptomeria japonica?
You can propagate Cryptomeria japonica through semi-hardwood cuttings taken in late summer or by sowing seeds in spring. Ensure proper care for successful rooting.
When should I prune my Japanese Cedar?
Prune Cryptomeria japonica in late winter or early spring before new growth begins to maintain its shape and remove any dead or damaged branches.
What pests affect Cryptomeria japonica?
Common pests include aphids and spider mites. Regularly inspect your plant and treat infestations with insecticidal soap or neem oil.
Is Cryptomeria japonica toxic to pets?
Cryptomeria japonica is non-toxic to pets and children, but ingestion of large quantities may cause mild gastrointestinal upset.
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