Siberian Irises

Discover the tough-as-nails beauty found in Siberian iris.

'Butter and Sugar' Siberian Iris

'Butter and Sugar' Siberian Iris

©2011, Dorling Kindersley Limited

2011, Dorling Kindersley Limited

Easy and trouble-free, ‘Butter and Sugar’ Siberian iris forms clumps of grassy foliage with a late spring display of butterfly-like flowers. These bicolored blossoms are large, with creamy white standards and butter-yellow falls.

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Give your garden a pop of color with Siberian irises. These low-maintenance bloomers open flowers from mid-spring to early summer, giving any landscape a reliable, long-lasting show. Despite the name, Siberian iris aren’t native to Siberia, but hail from an area that runs from Northern Italy into Turkey and Southeastern Russia. Nevertheless, Siberian iris bring a sturdy presence to the garden, boasting winter hardiness from Zones 3 to 9. 

Siberian iris are known botanically as Iris sibirica. They open flowers that have a classic iris form with several upright petals skirted by cascading petals known as falls. The most common color among Siberian iris is a purple or blue iris bloom. The blossoms are beardless, meaning they lack the line of fuzz like appears on the falls of a bearded iris flower. 

This group of iris differs in other ways from their bearded iris cousins. Where bearded iris need full sun to flower, Siberian iris can tolerate some shade. In hot Southern locales, they prefer light shade during the hottest part of the afternoon. You’ll get the strongest flower display from Siberian iris in more temperate zones by siting plants in full sun. 

Give Siberian iris soil that’s high in organic matter and slightly acid. Amending soil with compost, humus, composted oak leaves or peat moss can help maintain a slightly acid soil base. This iris prefers a moister soil. They’re often planted near pond edges, but while Siberian iris like moist soil, they cannot grow in standing water. This is the iris of choice for clay soils. 

Siberian iris grow two to four feet tall and have grassy leaves that arch over at the tips. The leaves form an attractive clump in the garden that’s virtually care-free. This perennial can easily grow into clumps that measure several feet across in the course of a few years. You’ll know you need to divide clumps when the center dies out or when flower number and size diminish. 

The right time to divide Siberian iris depends on where you garden. In colder northern zones, divide plants in early spring (best time) or late summer (second-best time). In southern zones, divide plants in fall. In all cases, keep newly planted Siberian iris well-watered during their first year of growth, and mulch plants for winter using several inches of a porous material that allows water to flow freely through it. 

Look for Siberian iris that open flowers in shades of blue, purple, pink, red, white, yellow and orange. After flowering, cut down spent flowers to prevent seed formation if you’re concerned about plants self-sowing. Siberian iris aren’t invasive, but will self-sow. If you let seed pods form, you’ll find they have sturdy stems and make nice additions to dried arrangements. 

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