Oregon · Washington · Idaho
When to plant Oregon iris
Plant in the garden: Portland and Seattle Mar 1 – Apr 26; Spokane Apr 1 – May 27; Boise Mar 20 – May 15; Bend Apr 28 – Jun 23.
Your dates in
Oregon iris (Iris tenax) is a native iris that forms clumps of narrow, grassy leaves about a foot tall. Its species name, tenax, means tough, after the strong leaf fibers that Native peoples twisted into cord and nets.
Puts Oregon iris on your free plan, with dates for your town and a spot in your beds.
- Difficulty
- Easy
- Sun
- Full sun to light shade
- Spacing
- 12 to 18 inches apart
- Planting depth
- Same depth as in the pot; rhizomes just below the soil
- Frost
- Hardy perennial; comes back every year
- First harvest
- Blooms in late spring
A tough native iris with grassy leaves and lavender to deep purple flowers in late spring. It likes sun to light shade and dry summers, and dislikes being moved, so plant it where it can stay.
Oregon iri planting dates
| Towns | Plant in the garden |
|---|---|
| Portland, OR, Seattle and Tacoma, WA | Mar 1 – Apr 26 |
| Spokane, WA | Apr 1 – May 27 |
| Boise and Meridian, ID | Mar 20 – May 15 |
| Bend and Redmond, OR | Apr 28 – Jun 23 |
| Astoria, OR | Mar 25 – May 20 |
Dates for six main cities. For any of the other 80 towns, type it in the box at the top of the page or browse all towns.
| Gresham, OR, Oregon City and West Linn, OR, Portland, OR, St. Helens and Scappoose, OR, Wilsonville and Canby, OR | Mar 1 – Apr 26 |
|---|---|
| Hillsboro and Beaverton, OR | Mar 5 – Apr 30 |
| Corvallis and Albany, OR, Eugene, OR, Salem, OR | Mar 1 – Apr 26 |
|---|---|
| Cottage Grove, OR | Mar 13 – May 8 |
| McMinnville and Newberg, OR | Mar 4 – Apr 29 |
| Ashland and Talent, OR | Mar 25 – May 20 |
|---|---|
| Grants Pass, OR, Medford, OR, Roseburg, OR | Mar 1 – Apr 26 |
| Astoria, OR, Brookings and Gold Beach, OR, Coos Bay and North Bend, OR, Newport and Lincoln City, OR, Tillamook, OR | Mar 25 – May 20 |
|---|
| Bend and Redmond, OR, Klamath Falls, OR | Apr 28 – Jun 23 |
|---|---|
| Burns, OR | Apr 30 – Jun 25 |
| Lakeview, OR | Apr 23 – Jun 18 |
| Madras, OR, Prineville, OR | Apr 20 – Jun 15 |
| Baker City, OR, Enterprise and Joseph, OR, John Day, OR | Apr 20 – Jun 15 |
|---|---|
| Hermiston, OR, Hood River, OR, Ontario, OR, Pendleton, OR, The Dalles, OR | Mar 20 – May 15 |
| La Grande, OR | Apr 1 – May 27 |
| Bremerton and Port Orchard, WA, Everett, WA, Kent, Renton and Auburn, WA, Seattle and Tacoma, WA | Mar 1 – Apr 26 |
|---|---|
| Olympia, WA | Mar 18 – May 13 |
| Shelton, WA | Mar 16 – May 11 |
| Anacortes, WA, Bellingham, WA, Friday Harbor and the San Juans, WA, Mount Vernon and Burlington, WA, Oak Harbor and Whidbey Island, WA | Mar 1 – Apr 26 |
|---|
| Aberdeen and Hoquiam, WA, Forks, WA, Long Beach and Ilwaco, WA | Mar 25 – May 20 |
|---|---|
| Port Angeles, WA, Port Townsend, WA | Mar 1 – Apr 26 |
| Sequim, WA | Mar 10 – May 5 |
| Centralia and Chehalis, WA | Mar 11 – May 6 |
|---|---|
| Longview and Kelso, WA, Vancouver, WA | Mar 1 – Apr 26 |
| Chelan, WA, Wenatchee, WA | Mar 20 – May 15 |
|---|---|
| Leavenworth, WA, Omak and Okanogan, WA | Apr 1 – May 27 |
| Winthrop and Twisp, WA | Apr 3 – May 29 |
| Ellensburg, WA | Apr 1 – May 27 |
|---|---|
| Ephrata and Quincy, WA, Moses Lake, WA, Sunnyside, Grandview and Prosser, WA, Tri-Cities (Pasco, Kennewick, Richland), WA, Walla Walla, WA | Mar 20 – May 15 |
| Goldendale, WA | Apr 7 – Jun 2 |
| Yakima, WA | Mar 27 – May 22 |
| Colville, WA, Pullman, WA, Spokane, WA | Apr 1 – May 27 |
|---|
| Bonners Ferry, ID, Coeur d'Alene and Post Falls, ID, Sandpoint, ID | Apr 1 – May 27 |
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| Lewiston, ID | Mar 20 – May 15 |
|---|---|
| Moscow, ID | Apr 1 – May 27 |
| Boise and Meridian, ID, Emmett, ID, Nampa and Caldwell, ID | Mar 20 – May 15 |
|---|---|
| McCall, ID | May 11 – Jul 6 |
| Burley and Rupert, ID, Idaho Falls, ID, Pocatello, ID, Rexburg, ID, Twin Falls, ID | Apr 1 – May 27 |
|---|---|
| Salmon, ID | Apr 20 – Jun 15 |
Oregon iri year at a glance
| Task | J | F | M | A | M | J | J | A | S | O | N | D |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Plant | Mar | Apr | ||||||||||
| In bloom | Apr | May |
Around Portland. Colder towns, especially east of the Cascades, run a few weeks later; the table above has your town's planting dates.
How to grow Oregon iris
- Pick a spot in sun or light shade with soil that drains well. Dry summer slopes and meadow edges suit it.
- Plant Oregon iris plants on your city's dates, 12 to 18 inches apart. Same depth as in the pot; rhizomes just below the soil.
- Water through the first summer only. It needs no fertilizer.
- Harvest: Enjoy the flowers in late spring. Leave the leaves standing through summer; trim old ones in late winter.
Growing Oregon iris in your part of the Northwest
The same plant behaves differently on the wet west side, the foggy coast and the dry, colder east side.
West-side valleys
Willamette Valley, Puget Sound, southern Oregon
Oregon iris is native to west-side meadows and open woods and needs no summer water once established.
East of the Cascades
Columbia Basin, Yakima, Boise, Spokane, north Idaho
Rocky Mountain iris is the iris native to east-side meadows and is the better choice there.
More Oregon iri varieties
More widely sold picks that do well somewhere in the Northwest. The tag says which part of the Northwest suits each one best.
Oregon iris
Sold as the wild species by native plant nurseries. Usually lavender to purple, with grassy leaves.
West side
Pacific Coast hybrid irises
Hybrids of Oregon iris and its West Coast relatives, in a wide range of colors. They need the same dry summers and good drainage.
West side
How much to grow
How many to plant
Plant 3 or more, about 1 foot apart. Clumps widen slowly.
Key numbers
- West sideNative range
- April–JuneBloom
- 12–18 inHeight
- Fall onlyDivide
Top care tip: Leave established clumps alone, and divide only in fall after the rains start.
Growing notes
What makes the difference in Northwest gardens, in plain language.
A tough native iris
Oregon iris, Iris tenax, grows wild in meadows, open woods and roadsides in western Oregon and southwestern Washington. Its flowers are usually lavender to deep purple, but white, cream and yellow forms occur.
The narrow, grassy leaves form a tidy clump. They're so tough that tenax means tenacious; people once used the leaf fibers to make cord.
Planting
Plant in full sun to light shade in soil that drains well. It handles clay if water doesn't stand on it, and it likes dry summers. Water through the first summer only.
Pacific Coast hybrid irises are garden hybrids of Oregon iris and its relatives, with a wider range of colors. They need the same care.
Moving and dividing
Oregon iris dislikes being disturbed. Clumps dug in spring or summer often die. If you need to divide it, do it in fall after the rains start, when new white roots are growing.
Trim old, dead leaves in late winter. It needs no fertilizer.
Good neighbors
Grows well with
- Western columbine. The same sun to part shade.
- Camas. Shares open meadow sites.
Pests and problems
What most often goes wrong with Oregon iris in Northwest gardens, how to spot it and what to do.
Moving it
Signs: Clumps sulk or die after dividing in spring.
What to do: Divide only in fall, after the rains start.
Slugs
Signs: Chewed leaves and flowers.
What to do: Slug bait in spring.
Common questions about growing Oregon iris
When should I plant Oregon iris in Oregon, Washington and Idaho?
Plant in the garden: Mar 1 – Apr 26 in Portland and Seattle, Apr 1 – May 27 in Spokane, Mar 20 – May 15 in Boise and Apr 28 – Jun 23 in Bend. Pick your town at the top of the page for your own dates.
When does Oregon iris bloom?
From April to June, depending on elevation and how warm the spring is.
Can I divide Oregon iris?
Yes, but only in fall after the rains start, when new roots are growing. Divisions made in spring or summer often fail.
Does Oregon iris need water in summer?
Not once established. It's adapted to dry summers, and summer watering can rot it.
See what else to plant in March or April.
Huckleberries
Oregon grape
Red-flowering currant
Serviceberry
Camas
Thimbleberry
Salmonberry
Salal
Kinnikinnick
Western columbine
Douglas aster
Oregon sunshine
Pacific ninebark
Sword fern