Plant of the Month for June, 2017

arisaema sikokianum header
Arisaema sikokianum

 (air-uh-SEE-muh  si-ko-kee-AH-num)

General Information:

If you think Jack-in-the-pulpits are plain looking you have not seen this queen of the arisaems, Arisaema sikokianum. One look and you will desire her.

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Arisaema sikokianum:photo by Robert Pavlis

As a member of the aroid family this flower has a white protruding sex organ called a spadix, surrounded by a dark purple pitcher, the spathe. The white spadix glows in a shady garden and can be spotted from quite a distance. The plant will be shorter with smaller leaves in more light and larger in heavier shade. A. sikokianum is one of the first arisaemas to flower – late May in zone 5. By mid-summer it will have gone back underground. If you are lucky, the seed head will continue to ripen until fall, producing spectacular read berries.

This plant is also known as the circumcised Japanese Jack-in-the-pulpit, the Japanese cobra lily, the Japanese dragon arum and my favourite, the gaudy Jack. The flower is single-sexed but it can change its sex from year to year. Both sexes need to be present in order to form seeds and it will cross pollinate with closely related species.

arisaema sikokianum closeup

Arisaema sikokianum:photo by Robert Pavlis

Unlike many arisaema, this one rarely produces offsets. The best way to propagate it is from seed which takes 3-4 years to flower. Seed germinates fairly easily at room temperatures.

Life Cycle: perennial

Height: 45cm (1.5ft)

Bloom Time: spring

Natural Range: Japan, China

Habitat: woodland edges

Synonyms:  Arisaema sazensoo, Arisaema mafnificum, Arum sazensoo


Light: part shade

Soil: moist but well drained

Water: medium to wet

USDA Hardiness Zone: 4– 9

Propagation: seed, seldom produces offsets

Seedex availability (ORG&HPS annual Seed Exchange): regularly


Requires darkness.
Pulpy coat inhibits germination. Remove by soaking and rinsing in clean water daily for approximately 7 days. Discard water.
Sow @4°C for 3 weeks, then place @20°C.
ORG&HPS member Bill Snowden brought this article to our attention In brief, for best germination collect seed when fruit turns red (in December), wash 3 times in water to remove coating, dry at 20° for 1 month. Sow, place pot at 4° for 6 weeks then 15 to 20° in the dark. Germination is enhanced by GA3. Keep in seed pot for 2 years
Robert Pavlis