Northern blue flag carries blue-purple flowers above upright, blue-green leaves, forming clumps beside ponds and in other consistently wet parts of the garden.
- Height
- 60–92 cm / 2–3 ft
- Spread
- 60–77 cm / 2–2.5 ft
- Light
- Full sun / Partial shade
- Soil moisture
- Moist, well-drained / Wet
- Foliage
- Deciduous
- Maintenance
- Low
- USDA zones
- 3a–9b
Planting
Choose rich, moist soil in full sun or partial shade. This iris also grows at pond margins in shallow fresh water, up to about 10 cm deep.
Care
Divide the rhizomes after flowering when you need more plants. After the first frost, cut the leaves back to just above the crown.
Before planting: Harmful if swallowed; sap, seeds and rhizomes can irritate skin. Wear gloves when handling.
Planting Northern blue flag?
Find a landscaper nearby to help with planting and establishment.
Find a landscaperMore plants to explore
Sources & photo credit
Plant reference: NC State Extension Gardener Plant Toolbox. Content checked . Flowering seasons vary with local climate; USDA zones describe winter cold tolerance.
- Northern blue flag: Danielle Langlois · CC BY-SA 3.0. Resized, converted to WebP and cropped for display.
- Dwarf crested iris: cultivar413c · CC BY 2.0. Resized, converted to WebP and cropped for display.
- Japanese roof iris: Photo by Jason Sturner · CC BY 2.0. Resized, converted to WebP and cropped for display.
- Siberian iris: Cathy Dewitt · CC BY 4.0. Resized, converted to WebP and cropped for display.