Blue Flag Iris is a perennial grown for its blooms, which open in summer and return year after year. Notably, it shrugs off deer. Its summer flowers are a moderate draw for native bees and butterflies.
Zones
Data not available
pH Range
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Sun
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Days to Maturity
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Score Blue Flag Iris on your exact land.
Zone averages can't see the slope, soil, frost, and sun that decide whether blue flag iris actually takes — and those shift from one yard to the next. Enter your address and we'll score blue flag iris against your land's real conditions.
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What Blue Flag Iris is
Blue Flag Iris grows as a perennial and reaches around 2.5 feet at maturity. It blooms in summer. It's also deer-resistant.
How to grow Blue Flag Iris
USDA Zones
Data not available
USDA PHZM 2023
Soil pH
Data pending
USDA PLANTS Database
Sun
Data pending
plant_species_v5.csv
Drainage
Data pending
plant_species_v5.csv
Mature Height
2.5 ft
plant_species_v5.csv
Frost-Free Days
0+
plant_species_v5.csv
Start the season right
Plant blue flag iris in full sun, once the soil has warmed and frost risk has passed.
Match the soil
Pull a soil test from your local Extension lab to confirm pH and drainage match blue flag iris's needs before planting.
Water steadily
Keep the root zone evenly moist through establishment. Match watering to the plant's drainage preference and your local rainfall.
Harvest at its peak
Cut blue flag iris blooms in the cool of the morning, just as they open, for the longest display.
Good to know
One caution for pet owners — blue flag iris is toxic to dogs and cats (moderate severity). Keep it out of reach, and call ASPCA Animal Poison Control at (888) 426-4435 in an emergency. (Source: ASPCA.)
Blue Flag Iris offers moderate value to bees and other pollinators. (Source: Xerces Society, Pollinator Partnership.)
Where Blue Flag Iris thrives
Whether blue flag iris thrives on a given site comes down to its soil pH, drainage, sun, and frost dates — the conditions that vary parcel to parcel.
See if Blue Flag Iris will thrive on your land
Zone averages are a start. Your exact soil pH, drainage, sun exposure, and frost dates shape whether blue flag iris actually takes — we score it against the real conditions at your address.
Three things about your exact spot that zone averages miss:
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Frequently Asked Questions
Can I grow Blue Flag Iris in my zone?
Zone data for blue flag iris is being finalized. A Growable Ground report checks your parcel's full suitability against federal soil, climate, and zone data.
When should you plant Blue Flag Iris?
Most growers plant blue flag iris after the last spring frost, once the soil has warmed. Your local frost dates set the exact window — a Growable Ground report reads them for your address.
What soil does Blue Flag Iris need?
Specific pH data for blue flag iris is pending. A soil test from your local Extension lab confirms what your site needs.
Does Blue Flag Iris attract pollinators?
Yes — blue flag iris's flowers are a solid nectar source for native bees and butterflies (Xerces Society, Pollinator Partnership).
Is Blue Flag Iris safe for pets?
Blue Flag Iris is toxic to pets (dogs,cats) with moderate severity. Keep it out of reach, and call ASPCA Animal Poison Control at (888) 426-4435 in an emergency.