Iris pseudacorus
Yellow flag
Common names: Yellow iris, Water flag
At a glance
- Light
- Full sun
- Pot size
- from 80 l
- Lifespan
- Perennial
- Flowering
- May–Jul
- Hardiness
- Hardy
- Origin
- Native to Germany
Photo: ABesheva · CC BY-SA 4.0 · Source
Description
Iris pseudacorus is a native wetland perennial that produces bright yellow flowers from May to July. It grows in dense, spreading clumps along pond edges, ditches, and wet meadows, providing an attractive vertical structure and serving as an important nectar source for bees. The sword‑shaped leaves give garden ponds and shorelines a clear, upright appearance. All parts of the plant, especially the rhizome, contain toxic compounds; contact with skin, mucous membranes, or eyes should be avoided, and the plant should not be ingested by children or pets.
Care instructions
Iris pseudacorus prefers a sunny to partially shaded location with constantly moist to shallowly flooded soil, ideally at a pond edge in 5 to 15 cm water depth. Plant the rhizomes in spring (around mid‑April, week 16) just below the soil surface in nutrient‑rich, loamy substrate. After flowering, cut back spent stands after seed maturity if you wish to prevent uncontrolled self‑seeded spread. Every three to four years, the clump can be divided in autumn to keep the plant vigorous and limit its spread. Wear gloves when dividing or cutting, as the plant sap can cause skin irritation.
The care notes were machine-translated from German.
Garden year
FloweringMay–Jul
Soil & site
Soil pH
Soil type
moist, nutrient-rich, humus-rich, clayey
The yellow flag iris wants it permanently moist to wet, ideally right at the pond edge or in shallow water up to 10 cm deep. Nutrient-rich, clayey to loamy soil with a high proportion of humus comes closest to its natural home in bank and marsh zones. Waterlogging is no problem for it, while it avoids completely dry sites.
Feeding
Medium feeder
Months
Apr–May
One trowelful of mature compost in spring, directly into the root zone, is quite enough as a starter feed. At the pond, you can additionally mix in well-rotted manure or a special pond planting compost when you plant it. This robust wild perennial needs nothing more; it feeds well on the nutrients in the moist soil.
Overwintering
The yellow flag iris is hardy in Central Europe and needs no special protection. The rhizome comes through even severe frost without trouble in the soil or under a thin layer of ice at the pond edge. You can cut wilted foliage close to the ground in late autumn, or leave it standing until spring as natural winter protection.
Propagation
Methods
- Division
- From seed
The easiest way is to divide the rhizomes after flowering, from about June into late summer. Dig up the rootstock, cut it with a sharp knife into pieces each with one strong shoot and replant them straight away in moist conditions. Sowing is also possible but needs patience: the seeds germinate only after a cold period, and the young plants often flower only in the third year. At the garden pond, the species also spreads by itself over the years through drifting seeds.
For your garden
Grow Yellow flag yourself
Gartenkern tells you when frost is coming, when to sow and when to harvest, for your location.
Free, no time limit
Notes from real gardens
What other gardeners have written down about this variety, anonymous and voluntary.
No notes shared yet. Will you be the first to write one down?