Siberian iris Iris 'Roisin' (Sib)

Water

Siberian irises, like 'Roisin', should be watered deeply to encourage root development, especially during the first growing season. Established plants typically require about one inch of water per week, whether from rainfall or irrigation. During the growing season, water them once a week with approximately 1.5 gallons per square yard. In hotter, drier weather, increase watering to maintain soil moisture. In colder months or periods of rainfall, reduce watering to prevent waterlogging, which can lead to root rot.

Light

The Siberian iris 'Roisin' thrives in full sun to partial shade. It's best situated in a spot that receives at least six hours of direct sunlight daily. However, in areas with very hot summers, providing afternoon shade can help protect the plant from excessive heat.

Temperature

Siberian irises like 'Roisin' are hardy and can tolerate a wide range of temperatures. They can survive winter temperatures as low as -40 degrees Fahrenheit and can handle summer temperatures well into the 90s. However, the ideal growing temperatures for these irises are between 50 and 75 degrees Fahrenheit.

Pruning

Pruning Siberian iris 'Roisin' involves removing spent flowers to prevent seed formation and cutting back the foliage to the ground in late fall after the first hard frost. Pruning is also necessary to remove any damaged or diseased leaves throughout the growing season. The best time to prune is after blooming and in late autumn.

Cleaning

As needed

Soil

Siberian iris 'Roisin' prefers well-draining soil with a pH of slightly acidic to neutral (pH 6.5-7.0). A mix that includes loam, peat moss, and coarse sand or perlite is ideal, ensuring good drainage and aeration around the roots.

Repotting

Siberian irises like 'Roisin' typically don’t require frequent repotting and can be repotted every 3 to 4 years. They perform best when undisturbed so only repot when they are overcrowded.

Humidity & Misting

The Siberian iris 'Roisin' tolerates a range of humidity levels but prefers average to high humidity. Consistently moist soil can support its humidity needs without the need for additional atmospheric humidity.

Suitable locations

• Indoor

  Ensure bright light, cool temps, and moist soil for indoor Siberian iris.

• Outdoor

  Plant in full sun to partial shade, in moist, well-drained soil.

• Hardiness zone

  3-9 USDA

Life cycle

The Siberian Iris, known as 'Roisin', begins its life cycle as a seed, which, once sown, will germinate in damp conditions with cool temperatures. After germination, the plant develops into a seedling with a small rosette of leaves at the soil surface. As it matures, the plant produces long, slender leaves and a strong rhizome system underground. Each spring, the Siberian Iris produces tall, sturdy stems that bear the characteristic vibrant blooms, typically in shades of purple, blue, or white. After flowering, which occurs in late spring to early summer, seed pods may form, distributing seeds that can give rise to new plants. In subsequent years, the plant continues to grow and expand through its rhizomes, clumping to form larger masses, and requires division every few years to maintain vigor.

Propogation

• Propogation time

  Late summer to fall

• Propogation: The Iris 'Roisin', a cultivar of Siberian iris, is typically propagated through division, which is best done in the late summer after flowering has tapered off or in the early fall. To propagate by division, carefully dig up the clump of irises, gently wash off the soil to better see the rhizomes and roots, and use a sharp knife to separate the clump into smaller sections. Each section should have at least one fan of leaves and a healthy portion of roots. Replant the new divisions promptly, placing them at the same depth they were growing before and about 18 to 24 inches apart to give them enough space to mature. Water the transplanted divisions thoroughly to help establish them. This method of propagation helps to rejuvenate older clumps that may have become crowded and ensures the gardener can create more plants to expand their garden or share with others.