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Kalopanax septemlobus

Castor Aralia · Prickly Castor Oil Tree · Castor-leaved Aralia

Family AraliaceaeGenus Kalopanax

A young tree with sparse yellowing lobed leaves on stiff upright branches, in a clipped garden
The whole plantSten PorseCC BY-SA 3.0

About the plant

What it is and where it grows — not part of any germination protocol.

The plant

Habit
TreeExtension Gardener Plant Toolbox
Habit
treePlants of the World Online
Height
40-60 ft12-18 mExtension Gardener Plant Toolbox
Spread
40-60 ft12-18 mExtension Gardener Plant Toolbox
Flower
WhiteExtension Gardener Plant Toolbox
Blooms
SummerExtension Gardener Plant Toolbox
Native range
China North-Central, China South-Central, China Southeast, Japan, Korea, Kuril Is. and elsewhereGBIF Backbone Taxonomy
Hardiness zones
4-7Extension Gardener Plant Toolbox

Growing conditions

Sun
Full sun; Partial ShadeExtension Gardener Plant Toolbox
Soil
High Organic MatterExtension Gardener Plant Toolbox
Soil pH
Acid (<6.0), Alkaline (>8.0), Neutral (6.0-8.0)Extension Gardener Plant Toolbox
Moisture
Good Drainage, MoistExtension Gardener Plant Toolbox

Toxicity is noted only where a source states it. No note here is not a finding of safety.

Sources: Extension Gardener Plant Toolbox — NC State Extension; Plants of the World Online — Royal Botanic Gardens, Kew; GBIF Backbone Taxonomy — Global Biodiversity Information Facility.

Worth knowing

  • Castor aralia is the only species in its genus. It is grown in Europe and North America for the tropical look of its large, hand-shaped leaves, yet it is very hardy, standing temperatures down to at least −40 °C. Wikipedia: Kalopanax

This source reports three treatments. All are shown.

Protocol 1

DerivedN. C. Deno, 1996

Difficulty High Rated by us, not by the source.

Start around October 2, 2027 for a May 3 last frost. Too late for spring 2027 — that needed starting on October 1, 2026.

  1. Warm moist stratification

    Duration: 90 daysTemperature: 70°F 21°C Light: dark

  2. Cold moist stratification

    Duration: 90 daysTemperature: 40°F 4°C Light: either

    16 germinated in this phase.

  3. Warm moist stratification

    Duration: 90 daysTemperature: 70°F 21°C Light: dark

about 6 months from start to step 3. Germination happens during step 3, in 6 days.

53% germination in 2–6 days.

Seed Germination Theory and Practice, 1st Supplement — N. C. Deno, 1996 · 1st Supplement, Kalopanax p. 51Public domain
Show the original text
Kalopanax (Araliaceae). K. pictus germ. 70D-40(16% in 9-12 w)-70D(53% in 2-6 d) and none in 40-70D-40 and 70 GA-3-40-70D. Light had no effect. All rotted in OT. Seeds DS 1 y germ. 70D-40-70D(22% in 2-8 d), and seeds DS 2 y were dead. Kedrostis (?).
Seed Germination Theory and Practice, 1st Supplement, 1st Supplement, Kalopanax p. 51. Quoted exactly. Every value on this card comes from this record, except the difficulty rating, which is ours; the step names come from a fixed list.

Protocol 2

DerivedN. C. Deno, 1996

Difficulty High Rated by us, not by the source.

Start around September 30, 2027 for a May 3 last frost. Too late for spring 2027 — that needed starting on September 29, 2025.

  1. Dry storage

    Duration: 365 daysTemperature: 70°F 21°C

  2. Warm moist stratification

    Duration: 90 daysTemperature: 70°F 21°C Light: dark

  3. Cold moist stratification

    Duration: 90 daysTemperature: 40°F 4°C Light: either

  4. Warm moist stratification

    Duration: 90 daysTemperature: 70°F 21°C Light: dark

about 1.5 years from start to step 4. Germination happens during step 4, in 8 days.

22% germination in 2–8 days.

Seed Germination Theory and Practice, 1st Supplement — N. C. Deno, 1996 · 1st Supplement, Kalopanax p. 51Public domain
Show the original text
Kalopanax (Araliaceae). K. pictus germ. 70D-40(16% in 9-12 w)-70D(53% in 2-6 d) and none in 40-70D-40 and 70 GA-3-40-70D. Light had no effect. All rotted in OT. Seeds DS 1 y germ. 70D-40-70D(22% in 2-8 d), and seeds DS 2 y were dead. Kedrostis (?).
Seed Germination Theory and Practice, 1st Supplement, 1st Supplement, Kalopanax p. 51. Quoted exactly. Every value on this card comes from this record, except the difficulty rating, which is ours; the step names come from a fixed list.

Protocol 3

DerivedN. C. Deno, 1996

  1. Cold moist stratification

    Temperature: 40°F 4°C

Germination happens during step 1.

0% germination.

Nothing germinated at 40.

This source doesn't state how long step 1 lasts.

Seed Germination Theory and Practice, 1st Supplement — N. C. Deno, 1996 · 1st Supplement, Kalopanax p. 51Public domain
Show the original text
Kalopanax (Araliaceae). K. pictus germ. 70D-40(16% in 9-12 w)-70D(53% in 2-6 d) and none in 40-70D-40 and 70 GA-3-40-70D. Light had no effect. All rotted in OT. Seeds DS 1 y germ. 70D-40-70D(22% in 2-8 d), and seeds DS 2 y were dead. Kedrostis (?).
Seed Germination Theory and Practice, 1st Supplement, 1st Supplement, Kalopanax p. 51. Quoted exactly. Every value on this card comes from this record; the step names come from a fixed list.

How each step is done, in Deno’s words, and what Verified and Derived mean.

Germination trials

Readers’ own records of sowing this species, published after review. Share your trial · All trials

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