What cause irises rhizome to rot?

Several factors can contribute to the rotting of iris rhizomes:

1. Poor Drainage: Irises prefer well-draining soil. If the soil is heavy clay or retains too much moisture, it can lead to waterlogged conditions around the rhizomes, increasing the risk of rotting. Improving soil drainage by amending with organic matter and avoiding overwatering can help prevent rhizome rot.

2. Overwatering: Excessive or frequent watering can saturate the soil and create overly moist conditions, which can lead to rot. It's important to water irises moderately and allow the soil to dry slightly between waterings. Avoid watering during periods of heavy rainfall or when the soil is already wet.

3. Crown Rot: Crown rot is a fungal disease that affects iris rhizomes. It typically occurs when the rhizomes are planted too deep or are covered with excessive mulch or soil. The fungus can attack the crown of the plant, causing rotting and eventual decline. Planting the rhizomes at the appropriate depth and avoiding excessive mulching can help prevent crown rot.

4. Poor Air Circulation: Lack of airflow around the plants can contribute to the development of fungal diseases and rot. Planting irises too closely together or in crowded conditions can hinder air circulation and create a favorable environment for rotting. Proper spacing and removing any overcrowded plants can promote better airflow and reduce the risk of rot.

5. Pests and Damage: Certain pests, such as iris borers, can bore into the rhizomes and create entry points for rot-inducing fungi or bacteria. Additionally, physical damage to the rhizomes, such as cuts or bruises, can make them more susceptible to rot. Regularly inspecting the plants for pests and taking preventive measures can help minimize the risk of rot.

To prevent rhizome rot, it's important to provide the right growing conditions for irises, including well-draining soil, moderate watering, proper planting depth, good airflow, and pest control. By practicing good cultural practices and monitoring the health of your irises, you can minimize the chances of rhizome rot and enjoy healthy, blooming plants.