Giant Sequoia Seeds

Giant Sequoia — Sequoiadendron gigantea

With the Giant Sequoia (Sequoiadendron giganteum) you grow one of the world's largest and oldest trees from seed. In its Californian homeland it reaches up to 90 m tall with trunks over 30 m around. The oldest specimens are more than 3000 years old. Frost-hardy down to -25 °C — thrives in Swiss parks and large gardens.

What's in the box

• 50 seeds Sequoiadendron gigantea — tested for germination
• Illustrated growing guide in 8 languages (on the seed card)
• Minimum shelf life: 2 years from packaging date

Growing in brief

• Prep: soak seeds 24 h in lukewarm water
• Sowing: in loose, moist seed compost
• Temperature: 20-22 nach Stratifikation °C
• Germination: Stratifikation 4-8 Wochen kalt, dann Keimung 4-6 weeks

Position & care in detail

• Light: full sun
• Humidity: normal (40-60 %)
• Substrate: well-draining, slightly acidic — mix of houseplant compost, sand and pine bark (3:1:1)
• Watering: regular when young, mature trees tolerate drought
• Feeding: little — 1-2× per season with organic complete fertiliser
• Wintering: Frost-hardy down to -25 °C

Sowing date & timeline

The ideal sowing date depends on the plant type.

Indoors sowing is possible year-round if heat mat and grow light are available. January to April is optimal: after germination the seedling can grow vigorously through spring/summer before light declines in autumn.

Directly outdoors only for frost-hardy species and after mid-May. Frost-tender species should first be raised in pots indoors, then hardened off after mid-May before being placed outdoors.

Pot choice & transplanting

Pot size and transplanting evolve with the plant:

• Sowing: 6×6 cm seed tray per seed or tray pots. Use low-nutrient seed compost.
• Seedling: prick out at 2-3 true leaves into a 9 cm pot with nutrient-rich compost.
• Established: repot every 1-2 years into a pot 2-3 cm larger. Mature plants need 5-30 L pot volume depending on the species.

Tips & tricks

• Use a heat mat: bottom heat at 25 °C speeds germination by weeks
• Mini greenhouse: cover seed tray with a transparent lid or cling film — keeps humidity high
• Prefer fresh seed: the fresher the seed, the higher the germination rate — sow soon after delivery
• Stratification mandatory: 4-8 weeks moist in fridge (4-5 °C)
• Protect young seedlings from winter sun
• Patience: 20-50 cm growth per year in the first 5 years

Good to know

• Native range: Sierra Nevada (California, USA), 1500-2300 m altitude
• Height: 90 m, in a pot 2-5 m
• At up to 90 m, one of the world's largest trees
• Lifespan over 3000 years — among the oldest living organisms
• Bark up to 60 cm thick, fire- and insect-resistant
• Frost-hardy down to -25 °C — cultivable in Swiss gardens

Seed storage

Unopened or leftover Saflax seeds keep for 2 years if stored correctly. Keep dry, cool (vegetable drawer in fridge) and in the original packaging — moisture drastically reduces germination. Test germinability before each sowing: 5 seeds on moist kitchen paper in a covered plastic dish at 22-25 °C — if 4-5 germinate, the rest are reliable.

FAQs

How long does germination take?
Typically Stratifikation 4-8 Wochen kalt, dann Keimung 4-6 at 20-22 nach Stratifikation °C. Bottom heat (heat mat) shortens germination significantly, often by half.

Can it grow outdoors?
Yes, year-round — frost-hardy down to -25 °C. In a sheltered position it thrives without issue.

How fast does it grow?
Slow in the first year (establishment phase), then notably faster from year two with optimal care and the right position.

Do I need special tools?
A simple seed tray, compost and a bright position are enough. A heat mat (~CHF 30) and a mini greenhouse noticeably improve germination but are not mandatory.

What if seeds don't germinate?
Patience — many exotic species take 4-12 weeks. Check temperature (heat mat!), substrate moisture (evenly moist, never wet) and whether the seeds require stratification or scarification. Saflax seeds are tested for germination before dispatch.

Can it grow in Switzerland?
Yes — Giant Sequoias thrive in Swiss parks, frost-hardy down to -25 °C and present in almost every castle park.

How old does it get?
Up to 3000 years — the oldest specimens in California are over 3200 years old.

How best to store leftover seeds?
In the sealed original packet, dry and cool (vegetable drawer of fridge at 4-8 °C). Germinability is preserved through the full 2-year shelf life. Reseal immediately after opening and acclimatise to room temperature before sowing.