Iris pseudacorus (Yellow flag)

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

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How to care

Watch out for

Specific pests

Sawflies

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

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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: 7^th March 2019 For more information visit: https://planthealthportal.defra.gov.uk/