At the end of the growing season, small corms develop at the base of the stems on top of the old withered corm. Some plants, such as Crocosmia, produce their corms in long chains.
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Step by step
- Carefully dig down in the soil with a trowel or hand fork and gently lift the corms, separate them and either replant at the original depth or smaller corms are best potted up in small pots.
- Chains of corms, such as with some Crocosmia, can be replanted intact or separated; usually maintaining the chains intact is the better option.
- Cormels, or cormlets, which are miniature corms, sometimes form between the new and old, withering corm.
- With these, carefully lift the corm at the end of the growing season when the plant is dormant.
- Remove the cormels, allow them to dry in indirect light for a week and then store them in a dry, cool (2-5C) place.
- Plant in pots the following spring, soaking first for a few hours if they have dried out, and grow them on. Cormels will take at least two years to reach flowering size.
- You can also propagate corms by cutting them into smaller sections while dormant.
- With small corms, or those that have few buds, you can remove the main stem by snapping it off or cutting it out to induce side buds to form shoots. At the end of the growing season, you will have several small corms or a large corm with several buds.
- Cut the corm into several pieces with a sharp, clean knife, ensuring that each piece has at least one good bud.
- Leave the pieces on a wire rack in a warm, dry place (18-21C) for 24 to 48 hours to allow the cut surfaces to seal.
- Once the pieces have developed a corky layer over the cut surface, plant each singly in small pots. Grow them on until they’re large enough.