Jack-in-the-Pulpit (Arisaema triphyllum) - purple flowers, illustrated plant card

Illustration

Jack-in-the-Pulpit

Arisaema triphyllum

Jack-in-the-Pulpit blooms from April through June.

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Bloom calendar

Bloom time

Apr–Jun

checked

Hardiness

Zones 4–9

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Sun

Part shade

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Water

Moderate water

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Mature size

20 in × 16 in

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Type

Bulb

house classification

Months here are Northern Hemisphere months; in the Southern Hemisphere, shift them by six months.

Plant it in part shade. It prefers moderate water. It is hardy in USDA zones 4–9. Expect it to reach about 20 in tall and 16 in wide at maturity, in roughly 1 year (a house reading).

Is Jack-in-the-Pulpit toxic to dogs or cats?

Listed as toxic to dogs and cats by NC State Extension and Pet Poison Helpline.
Listed as poisonous to people by NC State Extension.

Lists differ and none is complete. If a pet eats a plant and seems unwell, call a veterinarian or a pet poison helpline.

Verification

Planting record checked

What was checked

Nine facts were checked against named botanical sources, each recorded beside the sources that carried it: mature height and spread, hardiness zones, sun, water, bloom months and color, the trait tags, and years to mature size, which rests on a recorded house rule where no publisher states one and is marked so. Soil, diseases, pests, toxicity and the plant's own names have not yet been read for this plant, and its trait tags are the ones a feature uses rather than every word a page prints. Each fact above carries its own mark. The planting, spacing and size sections are derived from these checked facts by a fixed rule, not checked separately, and the plant type is the library's own classification.

See the 7 sources it was checked against

When to plant Jack-in-the-Pulpit

Jack-in-the-Pulpit is a fall-planted bulb: get it in the ground 6 to 8 weeks before the ground freezes, typically September or October in zone 6, the middle of its hardy zones 4 to 9. It pays you back the following April to June.

Month-by-month timing for your zone is on the planting calendar; if you garden near zone 6, the middle of this plant's hardy range, start with zone 6 in September. Derived from the plant's category, zones and bloom months plus typical zone frost dates, not checked separately.

How big does Jack-in-the-Pulpit get?

Illustration of Jack-in-the-Pulpit drawn to scale beside an adult — About 20 in tall and 16 in wide at maturity: knee-high beside an adult.

See Jack-in-the-Pulpit in a garden plan: the planner shows it in 3D beside everything else you add, growing toward this size over the years.

Where these facts come from

Jack-in-the-Pulpit's height, spread, hardiness zones, sun, water, bloom months and color and trait tags were checked against 7 published sources on October 25, 2026. Each one is linked below with every fact it carried, which can include a fact this page still marks as not yet checked, because a source carrying a value is not the same as the value being held to the standard. Facts not in that list, and the planting, spacing and size sections, are not covered by these sources.

Missouri Botanical Gardenheight, spread, hardiness zones, sun, water, bloom months and color and trait tags
NC State Extensionheight, spread, hardiness zones, sun, water, bloom months and color and trait tags
University of Illinois Extensionheight, hardiness zones, sun, water, bloom months and color and trait tags
Chicago Botanic Gardenhardiness zones, sun, water, bloom months and color and trait tags
Prairie Moon Nurseryheight, hardiness zones, sun, water and bloom months and color
openprairie.sdstate.eduSouth Dakota State University, Open PRAIRIEheight, sun, water and bloom months and color
Missouri Department of Conservationheight, bloom months and color and trait tags