Alphabetical Plant Listing

Iris missouriensis (Rocky Mountain Iris)

Rocky Mountain Iris, Western Blue Flag, Iris longipetala, Iris missouriensis var. arizonica, Iris missouriensis var. pelogonus, Iris pariensis, Iris tolmieana


Quite hardy, Iris missouriensis (Rocky Mountain Iris) is a spreading rhizomatous perennial boasting large, delicate, pale blue or blue-violet flowers, 2-3 in. long (5-7 cm), with deeply veined dark purple sepals adorned with a yellow-white signal. Blooming in late spring to early summer, 1-4 blossoms per stem, they are borne atop stout stalks that arise from dense clumps of long, narrow, arching blue-green leaves. The tough leaves are avoided by cattle and deer. Commonly found growing in wet meadows, dry steppes, and open woodland in western North America, this small rhizomatous perennial tolerate some dry soils once established but only after flowering. Rocky Mountain Iris is an excellent plant for sunny perennial borders or foundations.

  • Grows up to 12-24 in. tall (30-60 cm) and 10-12 in. wide (25-30 cm). Will spreads by rhizomes to form colonies.
  • Performs best in full sun in medium to wet, fertile, slightly acidic, well-drained soils. Some afternoon shade is welcomed in hot summer areas.
  • A welcomed addition to beds and borders, wall-side borders, city gardens, cottage gardens, coastal gardens.
  • Remove any dying foliage in fall, old flower stems can be cut down after flowering.
  • Keep an eye out for slugs, snails, whiteflies, thrips, gray mould. Deer resistant.
  • Roots are poisonous to humans.
  • Propagate by division of rhizomes from midsummer to early fall.
  • Native to North America, Mexico.

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Requirements

Hardiness 3 – 9
Heat Zones 1 – 9
Climate Zones 1, 1A, 1B, 2, 2A, 2B, 3, 3A, 3B, 4, 5, 6, 7, 8, 9, 10, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24
Plant Type Perennials
Plant Family Iris - Other
Exposure Full Sun, Partial Sun
Season of Interest Spring (Late)
Summer (Early)
Height 1' – 2' (30cm – 60cm)
Spread 10" – 1' (25cm – 30cm)
Spacing 12" – 20" (30cm – 50cm)
Water Needs Average, High
Maintenance Low
Soil Type Loam
Soil pH Acid, Neutral
Soil Drainage Moist but Well-Drained, Moisture Retentive
Characteristics Showy
Native Plants United States, California, Midwest, Minnesota, Nebraska, North Dakota, South Dakota, Pacific Northwest, Idaho, Oregon, Washington, Rocky Mountains, Colorado, Montana, Utah, Wyoming, Southwest, Nevada, Arizona, New Mexico
Tolerance Deer, Wet Soil
Attracts Hummingbirds
Garden Uses Beds and Borders, Wall-Side Borders
Garden Styles City and Courtyard, Coastal Garden, Informal and Cottage

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Guides with Iris - Other


By Danita Delimont, Shutterstock

While every effort has been made to describe these plants accurately, please keep in mind that height, bloom time, and color may differ in various climates. The description of these plants has been written based on numerous outside resources.


Requirements

Hardiness 3 – 9
Heat Zones 1 – 9
Climate Zones 1, 1A, 1B, 2, 2A, 2B, 3, 3A, 3B, 4, 5, 6, 7, 8, 9, 10, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24
Plant Type Perennials
Plant Family Iris - Other
Exposure Full Sun, Partial Sun
Season of Interest Spring (Late)
Summer (Early)
Height 1' – 2' (30cm – 60cm)
Spread 10" – 1' (25cm – 30cm)
Spacing 12" – 20" (30cm – 50cm)
Water Needs Average, High
Maintenance Low
Soil Type Loam
Soil pH Acid, Neutral
Soil Drainage Moist but Well-Drained, Moisture Retentive
Characteristics Showy
Native Plants United States, California, Midwest, Minnesota, Nebraska, North Dakota, South Dakota, Pacific Northwest, Idaho, Oregon, Washington, Rocky Mountains, Colorado, Montana, Utah, Wyoming, Southwest, Nevada, Arizona, New Mexico
Tolerance Deer, Wet Soil
Attracts Hummingbirds
Garden Uses Beds and Borders, Wall-Side Borders
Garden Styles City and Courtyard, Coastal Garden, Informal and Cottage

Guides with Iris - Other

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