Growing the Siberian Iris

Growing the Siberian iris (I. sibirica) is different than the bearded iris and well worth your attention, too.

March 29, 2016
Siberian Iris Purple

When you hear the word “iris,” do you see a big bearded beauty rising up above swordlike leaves? You’re thinking of the bearded iris (Iris germanica), a popular spring/summer garden star. The Siberian iris (I. sibirica), another flower entirely, is well worth your attention, too.

Easier to grow than I. germanica and needing very little care, I. sibirica has no beard but is beloved for its delicate flowers and soft, grasslike foliage.

The Siberian iris generally grows 2 to 4 feet tall; withstands wind, rain, and cold; and makes a lovely cut flower. Impressively, one mature plant can send out more than 20 stems of flowers at once, in a bloom season that lasts from late April to early summer. The Siberian iris quickly fills in spaces in a sunny border and works well at corners, too. Good companion plants are aquilegia, daisies, lupines, peonies, phlox, and pinks.

Best Conditions for Iris

The Siberian iris grows well in USDA Zones 2 to 9. In northern regions, grow it in full sun. It performs reasonably well in light shade where seasons are warm. In extremely hot southern climates, grow it in a shady location. Although it will tolerate dry periods, for best performance, plant it with perennials that you water well all summer long.

How to Plant Iris

Plant rhizomes with the crowns 1 inch below the soil level and cover them with soil—2 inches deep, if the soil is sandy. To avoid air pockets beneath the crown, make a small hill of soil in the center of the planting hole, place the rhizome on the hill with the roots spread around it, fill the hole with soil, and pack it tight. Keep evenly moist for 6 to 8 weeks after planting.

Ensure a Long Season

To have Siberian irises in bloom for the longest period of time, include both early and late varieties in your garden. Here are a few examples:

Early Bloomers: 

  • ‘Bouquet’
  • ‘Indy’
  • ‘Pleasures of May’

Late Bloomers:

  • ‘King of Kings’
  • ‘Liberty Hills’

For Best Iris Blooms

Remove spent flowers after they bloom to keep seed heads from forming. In late fall, cut foliage to the ground and mulch well after the ground has frozen.

After a few years, when large clumps form, divide them to ensure continued bloom. Dig mature iris plants in the spring or early summer after they bloom or in the early fall, well before frost threatens. Loosen the soil carefully and pry the rhizomes loose with a rocking motion. Cut the rhizomes with a sharp knife, leaving each new piece with two fan divisions. Plant the divisions, cover with soil to a depth of 1 to 2 inches (as directed), and keep the new plants evenly moist for 6 to 8 weeks after planting.

Photo: Michael thaler/shutterstock

The Top 12 Siberian Iris Varieties

  • Siberian irises come in a wide range of colors—purple, blue, pink, lavender, yellow, white, and bi- and tritones. In a poll, the Society for Siberian Irises (SSI) members put these varieties at the top of their list: ‘Roaring Jelly’
  • ‘Over in Gloryland’
  • ‘Jewelled Crown’
  • ‘Strawberry Fair’
  • ‘Coronation Anthem’
  • ‘Shaker’s Prayer’
  • ‘Lady Vanessa’
  • ‘Sultan’s Ruby’
  • ‘Lake Keuka’
  • ‘Mesa Pearl’
  • ‘Pink Haze’
  • ‘Somebody Loves Me’

Iris: What’s in a Name?

In Greek mythology, Iris is the name of the goddess of the rainbow. The iris bloom has been the symbol of monarchs and royal families throughout history. One of the earliest paintings of an iris is a fresco in King Minos’s palace on the Greek island of Crete. The palace dates from 2100 b.c.

The Bourbon kings of France, including Louis XIV, adapted the iris bloom on royal banners as the “fleur-de-lis.”

The iris is the state flower of Tennessee, and the fleur-de-lis is the emblem of the city of New Orleans, Louisiana.


Reader Comments

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Love your growth tips

Iris flower seeds.

Can I get iris flowers if I plant the seeds from in the spent flowers?

Low temperatures tonight and tomorrow night.

My Siberian irises have just budded and should be opening any day now. Tonight and tomorrow night the temp is going to be in mid 30s to low 30s. Will this harm the buds? Do I need to cover them?

Thank you!

Freezing Temps

The Editors's picture

It wouldn’t hurt to provide some extra protection during these unexpectedly cold nights! If you plan to use something like a sheet to cover them, create a sort of tent around the flowers with stakes to hold the sheets off the buds, if possible, in order to prevent the sheet from getting cold and wet and then resting directly on the buds. 

First iris photo - is a bearded iris

Your first photo looks like a bearded iris, not a Siberian iris.

Planting iris in spring

Since iris are such good growers. Can I plant some new ones this spring instead of fall?

The best time to plant irises

The Editors's picture

The best time to plant irises is in late summer and fall. But if you want to plant some this spring, feel free, however, you won’t have flowers until next spring. And note that bearded irises do not always flower the first year after planting.