The Iris genus, known for its striking, architectural flowers, is a popular ornamental plant found in gardens worldwide. While most gardeners propagate Irises by dividing the fleshy underground stems called rhizomes, the plants also produce true seeds after successful pollination. Understanding the physical characteristics of these seeds and the structure that protects them is the first step for anyone interested in propagating new Iris varieties. This process begins with recognizing the distinct container that holds the developing seeds.
Development and Appearance of the Seed Capsule
Following the fading of the flower, a small, swollen structure begins to form at the base of the bloom, marking the development of the seed capsule. This capsule is a dry, dehiscent fruit that holds the seeds and is often triangular or three-sided in shape. Initially, the capsule is firm and a vibrant green, blending in with the surrounding foliage.
The capsule requires approximately two months to fully mature after pollination, usually reaching ripeness in late summer or early fall. As it dries, the color transitions from green to a brittle, light or dark brown. The timing for harvest is indicated when the capsule naturally begins to split open along its seams, allowing the mature seeds to disperse.
Visual Characteristics of Mature Iris Seeds
Once the capsule splits open, the mature seeds are revealed, typically appearing plump and irregularly shaped. The size of an individual Iris seed can vary depending on the species, but they are generally comparable to a small BB or slightly larger. Seeds from different Iris types often display a range of distinctive traits.
For instance, seeds from Bearded Irises are frequently irregular and hard, while many Beardless Irises, such as those from the Siberian group, produce seeds that are flattened or D-shaped. The color of mature Iris seeds is most often a dark brown, black, or a deep golden-brown. They usually possess a hard, sometimes wrinkled, or waxy outer coat. This protective layer plays a role in the seed’s dormancy.
Preparing Seeds for Propagation
Harvesting should occur promptly once the seed capsule begins to crack open to prevent the seeds from dropping naturally. After collection, the seeds need to be removed from the pod and dried in a cool, dark place for a few weeks to ensure they are fully cured. This initial drying period is important for successful storage.
Before planting, Iris seeds must undergo a process called cold stratification to break their natural dormancy. This treatment mimics the cold, moist conditions of winter. Seeds are often soaked in water for one to two days to soften the hard seed coat before being placed in a refrigerator for 6 to 14 weeks in a moist medium like damp sand or vermiculite. This ensures the seeds are ready to germinate once they are planted.