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Plant Profile: Yellow Flag Iris (Iris pseudocornus)

One of the most successful plants in my bog garden is yellow flag, a rhizomatous, beardless iris. It’s long narrow sword-like leaves give a strong vertical accent to the garden and the bright yellow flowers in provide a splash of color in mid-spring. Yellow flag thrives in wet lands but also does well in a border with moist soils where it is less vigorous and, therefore, less likely to become invasive. It spreads by seeds and rhizomes and can form large dense colonies that are difficult to remove once established. Yellow flag has been used in sewage treatment because it can remove heavy metals from the soil. Historically, preparations from the roots have been used as snuff, the flowers for dye, and the rhizomes as a laxative. The flowers are lovely in bouquets and were probably the model for the fleur de lis, the heraldic emblem of French kings in the 12th century.

Type: Herbaceous perennial

Bloom: Yellow to cream flowers 3-4” across in mid-spring

Foliage: Long, narrow, sword-like leaves

Size: 3-5’ H x 2-3’ W

Light: Full sun to partial shade

Soil: Rich, wet to moist

Hardiness: Zones 4-9

Care: Control size if plant becomes invasive

Pests and Diseases: None of significance

Propagation: Seed, division in late summer to fall

Companion plants: Bog plants such as Venus fly trap, pitcher plant, sundew.

Outstanding Selections:

    ‘Berlin Tiger’ (yellow flowers with brown veining)
    ‘Crème de la Crème’ (white flowers)
    variegate (variegated foliage)

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