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Iris pseudacorus (Yellow flag)
1 hour care
per year
per year
1.5m
Max height
Max height
1.5m
Max spread
Max spread
2-5 years
To maturity
To maturity
Low
Toxicity
Toxicity
Plant details
Botanical name
Iris pseudacorus
Other names
Yellow fleur-de-lis, Water flag, Water skegs, Daggers, Flagon, Jacob's sword, Yellow flag, Yellow iris
Genus
Iris Iris
Species
I. pseudacorus - I. pseudacorus is an extremely vigorous, rhizomatous, deciduous perennial forming an extensive clump of erect, sword-shaped, grey-green leaves and, in summer bright yellow flowers with brown or purple- veined falls.
Iris pseudacorus is: Deciduous
Habit
Clump-forming, Erect
Toxicity
Severe stomach discomfort may result if ingested.
Flower
Yellow in Summer
Foliage
Green in Spring; Green in Summer; Green in Autumn
How to care
Watch out for
Specific pests
Sawflies Sawflies
Bacterial soft rot , Botryosphaeria fungus Bacterial soft rot , Botryosphaeria fungus
General care
Pruning
Remove faded flower stems to prevent any unwanted seedlings. Cut back when leaves start to yellow in autumn.
Propagation methods
Division
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Where to grow
Iris pseudacorus (Yellow flag) will reach a height of 1.5m and a spread of 1.5m after 2-5 years.
Suggested uses
Aquatic, Beds and borders, Bees (attract & feed bees), City, Coastal, Cottage/Informal, Low Maintenance, Waterside, Wildlife
Cultivation
Plant in autumn in full sun or partial shade in moist to wet, humus-rich, acid soil at pond or stream margins. Site carefully as may naturalize and form large colonies. Tolerates neutral soil. Do not allow to dry out.
Soil type
Clay, Loamy
Soil drainage
Moisture-retentive, Boggy damp conditions, Pond/In water
Soil pH
Acid
Light
Partial Shade, Full Sun
Aspect
South, East, West
Exposure
Exposed, Sheltered
UK hardiness Note: We are working to update our ratings. Thanks for your patience.
Hardy (H4)
Companion plants
Botanical name
Iris pseudacorus
Other names
Yellow fleur-de-lis, Water flag, Water skegs, Daggers, Flagon, Jacob's sword, Yellow flag, Yellow iris
Genus
Iris Iris
Species
I. pseudacorus - I. pseudacorus is an extremely vigorous, rhizomatous, deciduous perennial forming an extensive clump of erect, sword-shaped, grey-green leaves and, in summer bright yellow flowers with brown or purple- veined falls.
Native to
Garden origin
Foliage
Deciduous
Habit
Clump-forming, Erect
Toxicity
Severe stomach discomfort may result if ingested.
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Colour
Flower
Yellow in Summer
Foliage
Green in Spring; Green in Summer; Green in Autumn
How to care
Watch out for
Specific pests
Specific diseases
Bacterial soft rot , Botryosphaeria fungus
General care
Pruning
Remove faded flower stems to prevent any unwanted seedlings. Cut back when leaves start to yellow in autumn.
Propagation methods
Division
Monthly care advice
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Where to grow
Iris pseudacorus (Yellow flag) will reach a height of 1.5m and a spread of 1.5m after 2-5 years.
Suggested uses
Aquatic, Beds and borders, Bees (attract & feed bees), City, Coastal, Cottage/Informal, Low Maintenance, Waterside, Wildlife
Cultivation
Plant in autumn in full sun or partial shade in moist to wet, humus-rich, acid soil at pond or stream margins. Site carefully as may naturalize and form large colonies. Tolerates neutral soil. Do not allow to dry out.
Soil type
Clay, Loamy
Soil drainage
Moisture-retentive, Boggy damp conditions, Pond/In water
Soil pH
Acid
Light
Partial Shade, Full Sun
Aspect
South, East, West
Exposure
Exposed, Sheltered
UK hardiness Note: We are working to update our ratings. Thanks for your patience.
Hardy (H4)
USDA zones
Zone 8, Zone 7, Zone 6, Zone 5
Defra's Risk register #1
Plant name
Iris pseudacorus (Yellow flag)
Common pest name
Red rice root aphid; Rice root aphid
Scientific pest name
Rhopalosiphum rufiabdominalis
Type
Insect
Current status in UK
Absent
Likelihood to spread to UK (1 is very low - 5 is very high)
3
Impact (1 is very low - 5 is very high)
3
General biosecurity comments
Potentially significant glasshouse pest; growers should monitor for its presence. Routine aphid control should be effective in mitigating risk.
Defra's Risk register #2
Plant name
Iris pseudacorus (Yellow flag)
Common pest name
common blossom thrips; cotton bud thrips; tomato thrips
Scientific pest name
Frankliniella schultzei
Type
Insect
Current status in UK
Absent
Likelihood to spread to UK (1 is very low - 5 is very high)
2
Impact (1 is very low - 5 is very high)
3
General biosecurity comments
Polyphagous glasshouse pest; present in many countries; single finding in UK.
About this section
Our plants are under greater threat than ever before. There is increasing movement of plants and other material traded from an increasing variety of sources. This increases the chances of exotic pests arriving with imported goods and travellers, as well as by natural means. Shoot is working with Defra to help members to do their part in preventing the introduction and spread of invasive risks.
Traveling or importing plants? Please read "Don't risk it" advice here
Suspected outbreak? Click here for contact details to report to the relevant authority.
Date updated: 7th March 2019 For more information visit: https://planthealthportal.defra.gov.uk/
In order to add a note on this plant, please add this plant to your plant lists.
| This plant likes... | Garden match | |
| Soil types: | Clay, Loamy | Tell us... |
| Soil drainage: | Moisture-retentive, Boggy damp conditions, Pond/In water | Tell us... |
| Soil pH: | Acid | Tell us... |
| Light: | Partial Shade, Full Sun | Tell us... |
| Aspect: | South, East, West | Tell us... |
| Exposure: | Exposed, Sheltered | Tell us... |
| Hardiness: | Hardy (H4) | Tell us... |
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