Iris sibirica [EYE-ris, sy-BEER-ah-kuh] is an herbaceous perennial native to Europe, Central Asia, Armenia, Azerbaijan, and Siberia.
This member of the Iridaceae family is known for its delicate yet beautiful and showy blue flowers.
Their beauty is so well-loved in European countries Poland uses an illustration of the Siberian iris on their postage stamps.
They’re often grown in rain gardens and look great combined with other daylily plants.
You may hear this plant by its common name, Siberian Iris.
Siberian Iris Care
Size & Growth
In ideal conditions, the plant grows at a medium growth rate.
It can reach up to 2’ – 4’ feet in height and a spread somewhere between 3” inches and 1’ foot.
The plant has creeping rhizomes, forming a clump from which the stems grow with a bright green foliage color.
The plant type produces ribbed grass-like leaves about 10” – 30” inches long and less than 1″ inch wide.
They are shorter than the flower stems and die down with the foliage in the fall, reemerging in early spring.
Flowering and Fragrance
The plant bears purple flowers during the Spring bloom time while some varieties produce white flowers.
The stems rise above the foliage and have 2 – 5 flowers on each.
The flower color may range from the iconic purple to lavender, blue, and white with the occasional wine, pink, and yellow depending on the cultivar.
For instance, Caesar’s Brother bears deep purple flowers.
The small beardless flowers are 2” – 3” inches in diameter and have 2 pairs of petals, 3 larger sepals, and 3 inner smaller petals.
Light & Temperature
The plant is hardy to USDA Hardiness Zones 3 to 8.
Native to temperate climates, Siberian iris plants are quite hardy and drought-resistant.
It tolerates temperatures down to -4° degrees Fahrenheit (-20° C), especially when they are mulched.
The plant tolerates part shade but does best in full sun.
Add more mulch for the soil to sustain moisture for the bare root system.
Watering and Feeding
Iris sibirica plants require consistent regular watering for the first year.
Once the plant has established, space the watering so the soil is never dry but also not too wet.
If drought conditions persist, increase the frequency of watering.
In late spring, feed the plants with a nitrogen-rich fertilizer.
Fertilize again when you notice spent blooms.
Soil & Transplanting
Iris sibirica plants are tolerant of various types of soils such as clay soil and wet soil.
However, they grow best in well-drained, humus-rich, moist soil.
Organic medium or slightly acidic soils will do well.
Avoid soils with poor drainage or ones which tend to get too wet or too dry.
As for transplanting, the plant responds well when it is done immediately.
When you’re dividing the rhizomes in late summer, dig out the entire clump, cut foliage to approximately 6” or 8” inches and divide into sections.
Choose a location with plenty of sunlight (occasional partial shade) and well-drained soil.
If the soil is too dry, adding organic matter before transplanting helps.
You may have to mulch the plant come springtime.
Grooming and Maintenance
Regular pruning is not necessary for Siberian irises as they are low maintenance plants.
Just remove yellowing or dying foliage in the fall.
To encourage better flowering, cut and remove old stems once the flowering season has passed.
How to Propagate Iris Sibirica
The best way to propagate Siberian iris is with seeds.
The seeds are suitable for winter sowing.
- Sow the seeds in the soil after carefully scarifying or nicking the seeds.
- Once done, sow indoors in individual pots and keep them in 64° – 68° degrees Fahrenheit (18° – 20° C) for about 4 weeks.
- After this, move the seeds to a lower temperature location between 40° – 53° degrees Fahrenheit (4° – 12° C).
This will aid the germination process.
Keep in mind germination in these plants is erratic.
Another option is to propagate the plants by dividing the rhizomes in the early summer of late fall.
Iris Sibirica Pest or Disease Problem
Siberian iris plants are generally pest-free.
However, the plant has some susceptibility to certain problems including those experienced by bearded iris.
These typically include problems such as iris border and bacterial soft root.
Also, the occasional slug, snail or thrip attack is not uncommon.
The plant is also deer resistant.
Similar to other iris species, most parts of the plant such as the rhizomes and leaves are poisonous.
If ingested in a large quantity, it may cause stomach pain and induce vomiting.
Also, the sap from the plant can irritate the skin or cause an allergic reaction if handled with bare hands.
Suggested Siberian Iris Uses
The beautiful and vibrant blooms of the Siberian iris mixes well with various other flowering perennials.
Add the plant in your garden design with other companion plants which grow well in the corresponding USDA Zone.
The plants grow successfully in moist locations and provide some of the best cut flowers.
Even though they usually last less than two days, they look beautiful whether placed on vases or added to a bouquet.
Back in the day, the Tara Tartars from West Siberia or Russia used to color cloth to a yellow shade with the Siberian iris.