Blue flag iris Iris versicolor
Blue flag iris (Iris versicolor) is a deciduous perennial flowering plant in the Iridaceae family, native to Eastern Canada and the north-eastern US. It grows 50–90 cm (20–35 in) tall and 40–60 cm (16–24 in) wide, wants full sun and high water, and is hardy to about -40 °C (-40 °F). Space plants about 40 cm (16 in) apart.
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Blue flag iris at a glance
| Type | Perennial flowering plant, deciduous |
|---|---|
| Family | Iridaceae |
| Mature height | 50–90 cm (20–35 in) |
| Mature spread | 40–60 cm (16–24 in) |
| Spacing | 40 cm (16 in) centre to centre |
| Sun | Full sun, at least 5 h of direct sun a day |
| Water | High; drought tolerance none, waterlogging tolerance high |
| Soil pH | 5–7.5 |
| Cold hardiness | About -40 °C (-40 °F) once established (roughly USDA zone 3) |
| Heat stress | Likely above about 32 °C (90 °F) |
| Flowering | from about June for 3–4 weeks (northern hemisphere; later in cold climates, earlier in warm ones) |
| Wind tolerance | Moderate |
| Pollinator value | High |
| Edible | Not grown as food |
| Native to | Eastern Canada and the north-eastern US |
| Common in gardens of | 🇨🇦 Canada, 🇺🇸 United States |
Is Blue flag iris toxic?
- People: moderately toxic
- Cats: moderately toxic
- Dogs: moderately toxic
- Parts: rhizome
Rhizomes cause vomiting and diarrhoea; sap irritates skin.
If a child or pet may have eaten part of a plant, call a poison centre or vet straight away.
Companion planting: what to grow with Blue flag iris
No well-documented helpful pairing. Group it with plants that like full sun and high water.
Questions about Blue flag iris
- How far apart should I plant Blue flag iris?
- About 40 cm (16 in) apart, centre to centre. A mature plant spreads 40–60 cm (16–24 in).
- Does Blue flag iris need full sun?
- Full sun: at least 5 hours of direct sun a day.
- How much water does Blue flag iris need?
- High water. Drought tolerance is none and waterlogging tolerance high.
- How cold-hardy is Blue flag iris?
- It tolerates about -40 °C (-40 °F) once established, roughly USDA zone 3.
- When does Blue flag iris flower?
- From about June for 3–4 weeks (northern hemisphere; later in cold climates, earlier in warm ones).
- Is Blue flag iris poisonous to cats and dogs?
- For cats it is moderately toxic; for dogs moderately toxic; for people moderately toxic. Rhizomes cause vomiting and diarrhoea; sap irritates skin.
- What grows well with Blue flag iris?
- There is no well-documented companion pairing for Blue flag iris. Group it with plants that like the same sun (full sun) and water (high).
Sources and evidence
Evidence grade A (A: strong evidence).
- VASCAN: Database of Vascular Plants of Canada, Canadensys / Université de Montréal Biodiversity Centre
- Missouri Botanical Garden Plant Finder, Missouri Botanical Garden
Notes and assumptions
- Provincial flower of Quebec. Grows at pond edges in up to 15 cm of water.
Reference values for planning, not horticultural, veterinary or medical advice. Varieties, soils and local climates differ: check with a local nursery or extension service.
Related plants
- Bearded iris Iris germanica
- Japanese iris Iris ensata
- Siberian iris Iris sibirica
- Dutch crocus Crocus vernus
- Gladiolus Gladiolus x hortulanus
- Freesia Freesia refracta hybrids
- Montbretia (crocosmia) Crocosmia x crocosmiiflora
- African iris Dietes grandiflora