Siberian Iris Care Guide (Iris Sibirica)

If you have a Siberian Iris, you’ll want to read the entirety of this Siberian Iris care guide so you can develop beautiful blooms.

The Siberian Iris, (Iris sibirica), is a perennial plant that provides a burst of color early in the spring season.

The Siberian Iris features gentle, grass-like foliage and beautiful flowers. The blooms are most commonly purple, although different varieties can feature other colors, such as yellow, white, blue, or pink.

They are among the easiest perennial flowers to grow and care for, and they can be divided and propagated through the growth of their underground rhizomes.

The Siberian Iris is not to be confused with its well-known cousin, the Bearded Iris (Iris germanica). While the Siberian variety may lack a “beard”, it is just as attractive and usually requires less maintenance. They are both perennial plants, returning year after year to provide your garden with a touch of color.

The Iris was made popular by French monarchs who employed a depiction of the Iris bloom on their “fleur-de-lis” royal banners. This is the official emblem of the city of New Orleans, while the Iris is also the state flower of Tennessee.

If you are thinking about growing these popular perennials, keep reading for our essential care tips for Siberian Iris gardening.

General Care Guide

The Siberian Iris is known to grow well in USDA Hardiness Zones 3 through 8.

They are resistant to deer and rabbits and are commonly used as a “border” plant, as their slim, green foliage provides an attractive appearance even when the plant is not blooming.

For a longer-lasting bloom season, feel free to mix and match early and late Siberian Iris varieties. For instance, the “Strawberry Fair” variety blooms in the early to mid-summer, while the “Over in Gloryland” variety is known to bloom in the late spring. Planting these two variations together will ensure a long season of beautiful Iris blooms.

Siberian Iris care is generally simple and easy.

They do not require much attention apart from adequate water, sun, and nutrients. If you choose to, Iris plants can be divided and transplanted in the early spring, summer, or fall seasons. By late fall, Siberian Iris plants will go dormant for the winter, reemerging to grow again when the warmth of spring arrives.

Amount of Sun

In warmer climates (approximately Zones 7 and 8), Siberian Iris should be grown in a shady location. In colder climates (approximately zones 3 and 4), Siberian Iris will only thrive if grown in full sun. Otherwise, Iris plants well in partial to full sun in most moderate climates.

Watering Frequency

Siberian Iris plants prefer regular waterings and well-drained soil. However, they can withstand droughts when necessary, although this may slow or prevent growth in the plant.

Be sure not to keep the soil too moist, as the roots are susceptible to rot.

They are best planted with other perennials in your garden that receive frequent watering. Place a 2 to 3-inch layer of mulch around your Iris plants to preserve moisture and help them survive any dry spells.

Fertilization

Siberian Iris plants do best with an annual fertilization. Since the blooms and the greenery of the plant utilize different nutrients, it is important to consider what type of fertilizer you will be applying. Fertilizers that are higher in nitrogen (the first number in the NPK labeling system) will promote foliage growth but will not do as much for the flowers. While compost or manure can be used, it is usually high in nitrogen levels.

A 5-10-10 fertilizer is a good choice. After the flowers have bloomed and died away, you can apply about ⅓ cup of fertilizer around the base of the plant. Lightly mix the fertilizer into the surface soil and water it in.

Fertilization is best performed after the blooms have appeared on your Siberian Irises.

Dividing Siberian Iris

Siberian Iris can be propagated from seed like most plants.

However, the species also features “rhizomes”, which refers to the thick underground stems that can send new roots down into the ground while also sending new stems to the surface.

These rhizomes form into a clump that can be broken apart and planted elsewhere, creating multiple plants from one.

Early spring, summer, or fall are good times to divide your Irises. Avoid the heat of summer, as the new plants will have a harder time establishing themselves. Also, it is best to wait directly after bloom season when the Iris flowers have fallen.

If your Irises are in their first year of growth, then the rhizomes will not be ready to separate. If the plants have been growing for a few years, then the clumps are usually big enough to divide.

Dig up an Iris clump and separate the rhizomes, using your hands, a spade, or a sharp knife. Make sure to leave each rhizome with two fan divisions.

Transplanting Siberian Iris

Once you have separated your rhizomes, you are ready to transplant them into your garden.

Place each division on the ground and cover with around 1 to 2 inches of soil. They can be planted slightly above soil level, creating a small 1 to 2-inch mound at each plant site.

Water regularly for at least two months, giving the new plants enough time to establish a healthy root system.

As mentioned above, Siberian Iris planting is best done in early spring, summer, or fall seasons. If you can transplant after the first signs of growth in the spring, that will work best. If not, just wait until after the blooms have fallen from the plants or after the heat of summer has passed. 

Siberian Iris Varieties

There are a wide range of Siberian Irises that are differentiated by the color and timing of their blooms. They all enjoy the same care regimens and their rhizomes can be divided in the same manner, as explained above. Most of the varieties enjoy partial to full sun.

Below are some popular varieties. As you keep reading, keep in mind the terms standards and falls. The top 3 petals of Iris flowers are referred to as “standards”, while the bottom 3 petals of the blooms are called “falls”.

Flight of Butterflies Siberian Iris

The “Flight of Butterflies” Siberian Iris features blue standards and white fall petals. The blooms appear in late spring or early summer. The plant will grow to around 36 inches in height.

Ruffled Velvet Siberian Iris

The “Ruffled Velvet” Siberian Iris features deep purple blooms with a light yellow vein at the base. These Iris flowers appear in the late summer or early spring season and grow to around 24 inches.

Butter and Sugar Siberian Iris

The “Butter and Sugar” Siberian Iris features white standards and yellow falls. The Iris variety blooms in late spring or early summer and will grow to around 28 inches tall.

Silver Edge Siberian Iris

The “Silver Edge” Siberian Iris features blue flowers with a distinctive silver edge around the petals. The unique variety blooms in late spring or early summer and can grow to around 30 inches in height.

King of Kings Siberian Iris

The “King of Kings” Siberian Iris is one of the largest varieties available. It features large white flowers with some yellow shading in the center. It will grow to a height of around 36 inches and bloom in the early summer.

These are just a few of the many Siberian Iris varieties that are available. New variations continue to appear as adventurous gardeners experiment with hybridization and selective breeding of Siberian Irises.

Siberian Iris Gardens: Beautiful Flowers and Foliage

Iris gardens are a popular feature in backyards or botanical gardens. This is due to the endless combinations that are possible by mixing and matching the different varieties of Iris plants in the garden. They also make an excellent feature in any mixed perennial garden, providing great foliage and blooms while only requiring minimal care.

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Happy Planting!

About the author: Carley Miller is a horticultural expert at TheGreenPinky. She previously owned a landscaping business for 25 years and worked at a local garden center for 10 years.

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