Why Ranunculus tubers rot shortly after planting?

Question

I live in zone 11. My climate is warm Mediterranean. Those plants marketed locally are Mediterranean too. There should be no problem to grow them, I thought, but I was wrong.

First, they are hybrids marketed only with the genus name, so no further classification is given.

The practice: Plant them in fall. Winter rains and declining temperatures will make them break dormancy. Package instructions say soak tubers in water for 24 hours before planting.

The problem: tubers rot. Some rot before sprouting, others rot after sending out their first few leaves.

attempts: i skipped the soaking stage, and tried my luck in the garden. In my latest attempt, I used a fast-draining cactus potting mix.

So far, no progress. My next window of opportunity is in the coming November.

Answer 1

Generally tender bulbs will suffer if they get cold, too wet, or too dry for long periods and particularly suffer if multiple conditions persist together. You may also have a garden soil with a high load of fungal spores in which case very little is required to trigger their activity.

Zone 11 should be plenty warm enough, so if we were to guess it might be towards wetness and soil that cannot breathe easily. Your effort to use a fast draining mix is maybe a good idea, but an alternative might be to mix in some sharp sand and raise up the bulbs in "hills" so that they stand plenty high relative to the surrounding soil. The same technique is helpful with squash seeds when they tend to rot, and even with avocado trees where we need to ensure that the roots are not sitting in water for any extended time. This way you can ensure that the bulbs do not dry out while establishing themselves but still have an opportunity to drain fast and allow air into the soil after heavy rain.