How to Grow Western Red Cedar Trees from Seed (Germination Guide)
The Western Red Cedar (Thuja plicata) is a long-lived Pacific Northwest evergreen native to British Columbia, Oregon, and Washington. It is valued for aromatic foliage, dense screening, wildlife habitat, and its ability to thrive in cool, moist forest conditions.
Growing Western Red Cedar from seed begins with a 24-hour pre-soak followed by 30 days of cold, moist stratification. After stratification, the seeds should be surface sown because they require light for germination. Tamp the soil, keep the surface consistently moist, and provide some shade without blocking the light the seeds need.
Quick Western Red Cedar Germination Guide
Pre-soak: Soak seeds in water for 24 hours
Stratification: Cold stratify for 30 days
Planting: Surface sow; do not bury
After sowing: Tamp the soil and keep moist
Shade: Cover the seed bed with some shade
Light: Required for germination
Outdoor option: Fall sowing in mulched beds is preferred to artificial stratification
Step 1: Soak Western Red Cedar Seeds for 24 Hours
Soak Western Red Cedar seeds in room-temperature water for 24 hours before beginning cold stratification.
After soaking, move the seeds directly into a damp stratification medium.
Step 2: Cold Stratify Western Red Cedar Seeds for 30 Days
Place the soaked seeds in a lightly damp medium such as vermiculite, peat moss, or another moisture-retaining seed-starting medium.
Place the seeds and medium inside a sealed plastic bag or lidded container and refrigerate for 30 days.
Duration: 30 days
Temperature: Approximately 33–40°F (1–4°C)
Medium: Damp, but not saturated
Location: Household refrigerator
Check the seeds periodically and keep the stratification medium consistently damp throughout the cold period.
Step 3: Surface Sow Western Red Cedar Seeds
After completing 30 days of cold stratification, the seeds are ready to sow.
- Fill a container or prepared seed bed with a fine, moisture-retentive but well-draining growing medium.
- Surface sow the seeds. Do not bury them.
- Lightly tamp the seeds against the soil surface.
- Keep the surface consistently moist.
- Provide some shade while still allowing light to reach the seeds.
Step 4: Provide Light and Some Shade
Western Red Cedar seeds require light for germination.
Do not cover them with soil after sowing. Provide bright, protected conditions and some shade so the seed bed does not dry too quickly.
Fall Sowing Option
Western Red Cedar seeds can also be fall sown outdoors in a mulched bed.
This method is preferred to artificial refrigerator stratification because natural winter conditions provide the cold period needed before spring germination.
If mulching the seed bed, use a light covering that protects the seeds without blocking the light they will need when germination begins.
Why Do Western Red Cedar Seeds Need Cold Stratification?
Western Red Cedar seeds benefit from exposure to cold, moist conditions before sowing.
The recommended treatment is 30 days of cold stratification.
Is Soaking Western Red Cedar Seed the Same as Scarification?
No. The recommended preparation is a 24-hour water pre-soak.
Physical scarification such as nicking, filing, or sanding is not required by this germination protocol.
Do Western Red Cedar Seeds Need Light to Germinate?
Yes. Light is required for germination.
Surface sow the seeds and do not cover them with soil. Lightly tamp them against the moist soil surface so they remain in good contact with the growing medium.
Why Should Western Red Cedar Seed Beds Have Some Shade?
Some shade helps protect the exposed seeds and shallow root zone from excessive heat and rapid drying.
The goal is bright, protected conditions rather than darkness. Avoid dense coverings that block the light required for germination.
How Should Western Red Cedar Seeds Be Watered?
Keep the soil surface consistently moist throughout germination.
Because the seeds remain exposed on the soil surface, use gentle misting or bottom watering so they are not washed away.
What Soil Is Best for Western Red Cedar Seeds?
Use a fine, moisture-retentive but well-draining growing medium.
The seeds need steady moisture, but stagnant, waterlogged conditions can encourage fungal problems and damage developing roots.
Western Red Cedar Seedling Care
Once seedlings emerge:
- Provide bright light with protection from severe heat
- Keep the growing medium consistently moist
- Avoid stagnant, saturated soil
- Maintain gentle airflow
- Protect very young seedlings from hot, drying wind
- Handle seedlings carefully during transplanting
Hardening Off Western Red Cedar Seedlings
Seedlings started indoors should be gradually acclimated to outdoor conditions before permanent planting.
- Begin with short periods outdoors in bright shade.
- Increase outdoor exposure gradually over 7–14 days.
- Introduce gentle morning sun before stronger exposure.
- Protect young plants from hot, drying wind.
- Keep the root zone consistently moist during the transition.
- Transplant once seedlings are acclimated.
Where Is Western Red Cedar Native?
Western Red Cedar is native to the Pacific Northwest.
Its native range includes British Columbia, Oregon, and Washington.
Where Should Western Red Cedar Be Planted?
Western Red Cedar performs best in cool, moist conditions with reliable soil moisture and adequate room for long-term growth.
Good growing conditions include:
- Light: Full sun to partial shade
- Soil: Moist, well-drained soil with organic matter
- Moisture: Consistent moisture, especially while young
- Climate: Cool to moderate conditions
- Space: Allow room for a very large mature tree and broad root system
How Large Does Western Red Cedar Become?
Western Red Cedar can develop into a very large, long-lived evergreen.
Choose the permanent planting site with mature height, canopy spread, and root development in mind. Avoid planting in narrow strips or immediately beneath utility lines.
Can Western Red Cedar Grow in Full Sun?
Yes. Western Red Cedar can grow in full sun when soil moisture is dependable.
Young trees may benefit from partial shade or protection from intense afternoon heat, particularly in warmer or drier climates.
Is Western Red Cedar Actually a Cedar?
Western Red Cedar belongs to the genus Thuja and the cypress family. It is not a true cedar of the genus Cedrus.
Is Western Red Cedar Valuable for Wildlife?
Yes. Dense evergreen foliage can provide cover and shelter for birds and other wildlife.
Young foliage may also be browsed by deer and other animals, so seedlings may need protection while establishing.
Common Western Red Cedar Germination Problems
Skipping the Pre-Soak
Soak Western Red Cedar seeds in water for the full 24 hours before cold stratification.
Using the Wrong Stratification Length
The recommended cold treatment is 30 days.
Burying the Seeds
Western Red Cedar seeds require light for germination. Surface sow them and do not cover them with soil.
Blocking Too Much Light
Some shade is beneficial, but dense covers or heavy mulch can prevent the light needed for germination from reaching the seeds.
Letting the Surface Dry Out
Surface-sown seeds can dry rapidly. Keep the seed bed consistently moist.
Washing the Seeds Away
Use gentle misting or bottom watering so the tiny seeds remain in place.
Keeping the Soil Waterlogged
Maintain reliable moisture while still allowing drainage and airflow around developing roots.
Exposing Young Plants to Hot, Dry Conditions
Western Red Cedar is adapted to cool, moist conditions. Protect young seedlings from prolonged heat and drying wind.
Ignoring Mature Size
This species can become a very large tree. Choose a permanent location with plenty of room for long-term growth.
Western Red Cedar Seed Germination FAQ
Do Western Red Cedar seeds need to be soaked?
Yes. Soak Western Red Cedar seeds in water for 24 hours before cold stratification.
How long should Western Red Cedar seeds be cold stratified?
Cold stratify Western Red Cedar seeds for 30 days.
How deep should Western Red Cedar seeds be planted?
Do not bury them. Western Red Cedar seeds should be surface sown and lightly tamped against the soil.
Do Western Red Cedar seeds need light to germinate?
Yes. Light is required for germination.
Should Western Red Cedar seed beds be shaded?
Yes. Provide some shade to help maintain moisture and reduce heat, but keep the seed bed bright enough for germination.
Can Western Red Cedar seeds be planted outdoors in fall?
Yes. Fall sowing in a mulched bed is preferred because natural winter conditions provide the required cold treatment.
Can Western Red Cedar seeds be stratified in the refrigerator?
Yes. Keep the seeds in a damp medium in the refrigerator for the full 30-day cold stratification period.
Grow Western Red Cedar Trees from Seed
Soak 24 hours → Cold stratify 30 days or fall sow outdoors → Surface sow → Tamp soil → Keep consistently moist → Provide some shade → Maintain light for germination
Western Red Cedar seeds need their winter, but they do not want to disappear underground afterward. Give them a 24-hour soak and 30 days of cold, then leave them at the surface where light can reach them. Keep the seed bed moist and protected, and that tiny beginning can eventually become an enormous Pacific Northwest evergreen.