It is not a native but naturalizes easily.
It is easy to grow, low-maintenance, and useful as an ornamental pond plant.
It is valued for its ability to live inwet areas of the landscapewhere many other plants would perform poorly.
The Spruce / Evgeniya Vlasova
Check with your local extension office for any limitations before buying.
However, if you are growing it in a water garden, give it full sun.
Water
This semi-aquatic plant likes wet soilit is difficult to overwater it.
The Spruce / Evgeniya Vlasova
Don’t let the soil dry out completely.
Gardeners in arid regions can mist their plants regularly to increase humidity.
Fertilizer
Yellow flag iris needs no more than an average degree of fertility in its soil.
The Spruce / Evgeniya Vlasova
Fertilize it in late winter or early spring withmanure tea.
If the iris grows in a garden pond populated with fish, it doesn’t need additional fertilizer.
Pruning
During the growing season, remove bloom-bearing stalks after the flower dies.
The Spruce / Evgeniya Vlasova
Here’s how:
It can take anywhere from 1 month to 6 months for the seeds to germinate.
Overwintering
After the foliage dies back completely in fall, trim the leaves to 1 inch.
Don’t apply a layer of mulch over yellow flag iris plants as winter approaches.
If the winter is particularly frigid, spread straw around the base of the plant.
Yellow flag iris can be grown in water as deep as 6 inches.
These pests will eat holes in the leaves, which may eventually cause the leaves to die.
What Do Yellow Flag Iris Flowers Look Like?
Yellow flag iris bears showy flowers consisting of 3 upright standard petals and 3 pendant petals.
It has striking, sword-shaped leaves that are a greenish-gray color.
How to Encourage More Bloom
Little work is required to encourage yellow flag iris to bloom.
Deadheading
After a flower dies, deadhead it, an action that sometimes prompts a second bloom.
If yellow flag iris is deprived of moisture, it grows less vigorously.
Yellowing Leaves
Too little light can cause leaves to turn yellow.
If light levels look accurate, yellow leaves could also be due to overwatering or poor drainage.
The rhizomes live for up to 10 years and support new growth for that length of time.
That prevents self-seeding but has no effect on rhizome spread.
Be prepared to pull up new plants every year.
North Carolina State Extension
Iris.
