If you are looking for a bright blue early summer bloomer for the pond edge, the Siberian iris is the perfect choice. This is how you grow the wild shrub correctly in your garden.
Profile of Siberian iris:
Scientific name: Iris sibirica
Plant family: iris family (Iridaceae)
Other names: Siberian flag
Sowing time: autumn
Planting time: best in spring, autumn is possible too
Flowering period: May to June
Location: sunny to partially shady
Soil quality: sandy to loamy, lime tolerant, moderately nutritious, humus rich
These information are for temperate climate!
Use in: flowerbeds, flower bouquets, flower meadows, single position, group planting, pond planting, flower garden, natural garden, water garden
Winter hardiness: hardy, USDA Plant Hardiness Zones: 6 (-20 °C / -5 °F)
Bee and insect friendly: Yes
Plant characteristics and classification of Siberian iris
Plant order, origin and occurrence of Siberian iris
The Siberian iris (Iris sibirica) belongs to the large genus of irises, which comprises about 300 species. But no, the perennial is not at home in Siberia. It belongs to the iris family (Iridaceae). Throughout Europe, it occurs sporadically in fens, on pond banks, in ditches or on damp meadows. Within North America, it is found in the damp ditches beside roadsides. This has also earned it the common name meadow iris in some countries. Everywhere the flower is endangered by draining or intensively fertilized agricultural land. It is classified as highly endangered on the Red List. Iris sibirica has been cultivated in the garden since the 16th century, it is already mentioned in Charlemagne’s estate regulations, and with its stylish flowers it was one of the preferred subjects in Art Nouveau.
Characteristics of Siberian iris
Typical for the Siberian iris are rhizomes that run just below the earth’s surface – that’s why it is added to the rhizomatous iris, in contrast to the bulbous iris. In the course of the time Iris sibirica forms dense clumps. Depending on the variety, the plants grow to a height of 30 to 150 centimeters (12 to 60 in), and several flowers appear on one shoot towards the middle and end of June.
The delicate, narrow leaves of Iris sibirica, which initially point upwards, are reminiscent of grasses and take on an attractive yellow to bronze coloring in autumn. They are fresh green, only 2 to 6 centimeters (0.8 to 2.4 in) wide and thus clearly differ from the usual “sword shape” of the other Iris species. The leaves grow up to 50 centimeters (20 in) long.
The three-part flower with light blue, dark blue veined petals opens from reddish buds in May and June. Up to five flowers sit on the branched shoot, which protrudes clearly above the leaves. The three inner petals are slightly darker than the outer ones. The hanging petals of the flower are smooth, therefore the Siberian iris is also assigned to the group of Beardless Iris. The standard leaf stands upright above the hanging petals.
The perennials form seed capsules, which have a high ornamental value even during the winter if they are dried out.
Siberian iris – cultivation and care
Iris sibirica is very adaptable: sunny and partially shady places in flat and hilly terrain are welcome.
A moist to fresh, moderately nutrient-rich soil with plenty of compost is the preferred choice of the meadow iris. It can also dry out in the short term. If the soil is too sandy or too clay you should mix some compost to the soil. The pH-value can vary between alkaline-rich and slightly acidic. Only high nitrogen levels are not tolerated. During the cultivation from the 1950s onwards, great importance was also attached to the adaptation to “normal” garden soils.
The best time of planting is in spring, from the end of March, but it can be planted till October, although experts believe that early planted Siberian iris develops better. A flat planting is important, the rhizomes should still look out of the ground with the upper third. The roots point diagonally downwards. The planting distance can vary depending on the variety, normally 25 centimeters (10 in) are appropriate.
Nitrogen should not be added to the Siberian iris, but a small amount of compost in spring is desirable. It is best to cut back wilted plants, so that not too much energy is put into the seed formation. The leaves should be cut back only in the next spring.
Every four to five years the clumps should be divided and replanted. To do this, one digs out the meadow iris and separates it into several parts. The outer parts are the most vital, so they are usually the only parts that are replanted. To reduce evaporation, cut the foliage back by about half before replanting.
The Siberian iris should be sown in autumn as it needs cold to germ. The seeds should be covered with soil 1 to 2 centimeters (0.4 to 0.8 in). Dividing the rhizomes usually leads faster to success and produces offspring true to the variety. Dividing is best done in late summer, early autumn.
Diseases and pests
For snails and mice, foliage and rhizomes are a favorite food. Iris rust and leaf blight are best combated by cutting off infested areas. If aphids spread on iris sibirica in the dry spring, simply spray them off with a strong water jet.
Siberian iris is hardy down to -20 °C / -5 °F. There is no need for winter protection.
Use in the garden
Original varieties of Iris sibirica fit well into a natural garden ambience, for example on meadows or at the edge of a pond. However, it cannot compete with strong grass clumps. Large-flowered and double varieties can visually compete with magnificent perennials without any problems. Planting partners in humid areas are for example globeflower (Trollius europaeus), Jacob’s ladder (Polemonium caeruleum), lady’s mantle (Alchemilla) and day lily (Hemerocallis). In the shrub bed, phlox, tradescantia and avens are excellent companions.
In the meantime, the Siberian iris is available in a wide variety of colors, and cultivators now also work with quadruple chromosome sets. Especially these triploid irises are usually more demanding and want to be taken care of more than those with a diploid chromosome set. Mostly you can recognize them by larger flowers and a wavy edge. Especially from Japanese and US-American cultivators double flowers are brought into play.