The flowers are rather flat, rising above green blade-like foliage.
Japanese irises thrive where other plants would fail miserably.
Therhizomesare planted in early fall.
The Spruce / Evgeniya Vlasova
Note that Japanese irises are toxic to people and pets.
Japanese Iris Care
Japanese iris is a bit fussy with its growing requirements.
They are not as easy to grow as manyother types of irises.
The Spruce / Evgeniya Vlasova
Soil
Japanese iris requires friable,loamy soilthat isslightly acidic (5.5 to 6.5).
Dense, compacted soil is not suitable.
Water
Japanese irises require more water than many landscape plants.
The Spruce / Evgeniya Vlasova
They need even less in the fall and winter, when excess water is harmful.
Japanese irises thrive in humid conditions and don’t do well in hot, arid climates.
Fertilizer
Established Japanese irises are heavy feeders though you should neverfertilizenew transplants.
The Spruce / Evgeniya Vlasova
Apply afertilizer high in nitrogenin the early spring and once more just after the bloom.
Dividing the clumps every few years prevents overcrowding, which decreases their ability to bloom.
The best time to divide Japanese irises is in spring or fall.
The Spruce / Evgeniya Vlasova
Shallow and wide plastic pots with good drainage make ideal containers for Japanese iris plants in standing water.
Use high-quality, humus-rich potting soil.
Overwintering
When planted in garden soil, Japanese iris does not need winter protection.
‘Japanese Harmony’ IrisMaureen Bates Photography / Getty Images
Container plants, on the other hand,require winterization to insulate the rootsfrom the cold.
Pesticides andinsecticidal soapwill help control these pests.
Japanese irises are not frequently browsed by deer.
‘Japanese Pinwheel’ IrisCourtesy of Iris Encyclopedia
How Long Does Japanese Iris Bloom?
The bloom lasts about two weeks.
What Do Japanese Iris Flowers Look and Smell Like?
‘Freckled Geisha’ IrisCourtesy of Iris Encyclopedia
Japanese irises have a distinct flattened appearance compared to other irises.
The three petals of the standard are considerably shorter.
Three large petals fall around the standard.
The flowers have a subtle sweet fragrance similar to violets.
This deadlheading prevents the plant from developing seeds.
Common Problems With Japanese Iris
Faded Colors
Usually, the Japanese iris boasts deep colors.
Fading colors occur after transplanting or due to extreme temperature changes.
Exposed rhizomes after a critter has dug the soil around the plants is another possible explanation for fading colors.
Check the planting depth and replant them shallower, one to two inches deep.
They will fail to bloom at all.
Dig up the rhizomes, cut away any affected ones, and amend the soil to improve drainage.
Japanese irises spread via underground rhizomes.
This is easy to prevent by dividing the clumps every few years.
Do not plant them more then three inches deep.
North Carolina State University Cooperative Extension.
