Illustration
Douglas Iris
Iris douglasiana
Also comes in blue, white and yellow.
Douglas Iris blooms from May through June.
Months here are Northern Hemisphere months; in the Southern Hemisphere, shift them by six months.
Growing Douglas Iris
Plant it in part shade. It prefers moderate water. It is hardy in USDA zones 7–8. Expect it to reach about 1.5 ft tall and 3 ft wide at maturity, in roughly 2 years (a house reading).
Is Douglas Iris toxic to dogs or cats?
- Listed as toxic to dogs and cats by NC State Extension, Pet Poison Helpline and Royal Horticultural Society.
- Listed as poisonous to people by NC State Extension and Royal Horticultural Society.
Lists differ and none is complete. If a pet eats a plant and seems unwell, call a veterinarian or a pet poison helpline.
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.
When to plant Douglas Iris
Plant Douglas Iris in early spring as soon as the soil is workable, or in early fall at least six weeks before your first frost, so roots establish in cool weather. In zone 7, the middle of its hardy zones 7 to 8, spring means March to May and fall means September or October. Once settled, it blooms from May to June.
Month-by-month timing for your zone is on the planting calendar; if you garden near zone 7, the middle of this plant's hardy range, start with zone 7 in March. Derived from the plant's category, zones and bloom months plus typical zone frost dates, not checked separately.
How big does Douglas Iris get?
1.5 fttall5 ft 7 inan adult3 ftwideSee Douglas Iris in a garden plan: the planner shows it in 3D beside everything else you add, growing toward this size over the years.
How far apart to plant Douglas Iris
Derived from the mature spread above by a fixed rule, not checked separately: spacing is the spread, center to center.
Space Douglas Iris about 3 ft apart, center to center, so each plant has room to reach its full width.
Add Douglas Iris to a garden plan and the planner draws it at its full width, so you see the spacing before you buy.
Where these facts come from
Douglas Iris' height, spread, hardiness zones, sun, water, bloom months and color and trait tags were checked against 8 published sources on October 23, 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.
- boethingtreeland.comBoething Treeland Farmsheight, spread, hardiness zones, sun, water and bloom months and color
- calfloranursery.comCalifornia Flora Nurseryheight, spread, sun, water, bloom months and color and trait tags
- store.theodorepayne.orgTheodore Payne Foundationheight, spread, sun, water, bloom months and color and trait tags
- devilmountainnursery.comDevil Mountain Wholesale Nurseryheight, spread, hardiness zones, water and bloom months and color
- Plant Delights Nursery/ Juniper Level Botanic Garden, North Carolinaheight, spread, hardiness zones, sun and bloom months and color
- calscape.orgCalifornia Native Plant Society, Calscapeheight, spread, sun, water and trait tags
- RHSRoyal Horticultural Societyheight, bloom months and color and trait tags
- spcni.orgSociety for Pacific Coast Native Irisbloom months and color and trait tags
How the checking works, and what each standard covers, is on the verified plants page.
Where it grows wild
Native to 2 states
United States: California, Oregon
Recorded growing wild in 20 counties.
Range data from the World Checklist of Vascular Plants, Royal Botanic Gardens, Kew (CC BY 4.0, adapted) and USDA PLANTS. How the native range is credited.
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Drop this plant onto a 3D plan, see how it fills in, and watch your whole garden bloom across the year.