Gadenin日本語Get the appDormancy is the growing condition, not a gap
Saffron crocus comes from a climate with a long, hot, rainless summer, and it evolved to sit that summer out underground. The corm finishes its year in late spring when the leaves yellow, then spends two to three months completely inactive while the soil above it heats and dries. That baking period is what triggers the flower buds to initiate inside the corm. A corm that spends summer in cool damp soil frequently comes up in autumn with leaves and no flowers at all, and often does not come up at all.
This is the single most useful thing to understand about the plant. Most bulb failures get blamed on the planting or the feeding, but with saffron the commonest cause of a disappointing autumn is what happened to the bed through the summer dormancy, when there was nothing visible to look at.
Do not plant saffron among summer annuals, in a bed on an irrigation line, or under a lawn sprinkler's throw. Water landing on a dormant saffron bed is the main way home plantings are lost.
How dry is dry enough
The target is soil that is genuinely dry down to the depth of the corms, not merely dry on the surface. In a free-draining raised bed in full sun, ordinary summer weather achieves this on its own even with occasional rain, because water passes through rather than sitting. In heavy ground, a wet week in midsummer is enough to start rot at the base plate of the corm.
| Summer conditions | Risk to the corms | What to do |
|---|---|---|
| Hot, mostly dry, free-draining bed | Low | Leave the corms in the ground and do nothing at all |
| Hot with heavy thunderstorms, sandy or gritty soil | Low to moderate | Leave in place; make sure no surface water runs into the bed |
| Warm and regularly wet, heavy or clay soil | High | Lift the corms once the leaves have gone and store them dry |
| Cool and wet all summer | Very high | Grow in containers that can be moved under cover, or lift every year |
Lifting and storing where summers are wet
Lifting is straightforward and gives you a chance to grade the crop, but it has to be done at the right moment. Wait until the leaves have died back entirely, so the corm has finished drawing everything back into itself, then lift before the ground has a chance to get soaked.
- Wait for complete leaf die-back The leaves must be brown and dry all the way to the base, usually in late spring. Lifting while any green remains cuts short the corm's build-up and costs you flowers in autumn.
- Fork the block up whole Push a fork in eight inches (20 cm) out from the edge of the block and lever the whole mass up rather than digging into it. Corms sit deeper than you remember and are easily sliced.
- Clean and grade them dry Rub off loose soil by hand once the corms have surface dried for a day. Do not wash them. Separate the large flowering-size corms from the small offsets and keep the grades apart.
- Store in the warm, not the fridge Spread the corms one layer deep in open trays in a dry, airy place at 70 to 85F (21-29C). Warmth in storage does the same job the summer soil would have done. A cold garage or a refrigerator will not initiate flowers properly.
- Check the trays twice Look through the trays once a month and remove anything soft or moldy immediately; one rotting corm will take its neighbors. Replant at the end of summer as soon as the first roots or a shoot tip appear.
Breaking dormancy at the right time
Dormancy ends on its own when the soil cools and moisture returns. Stored corms show it first: a white root initial appears at the flat base and, a little later, a pale shoot at the tip. That is the signal to plant, and there is no advantage in waiting. Corms left in trays after they have started rooting will produce weak first-year flowers, because the flower is drawing entirely on stored reserves and the roots are not yet in soil to support it.
For corms left in the ground, do nothing to hasten it. Resist the urge to water an empty-looking bed in late summer to wake it up. The first proper autumn rain, or a single soaking once the nights have cooled, is enough, and flowers often appear within two to three weeks of that first wetting.
What to note before the bed disappears
Before the leaves vanish completely in late spring, write down the exact date they finished and re-mark the corners of the block. From that day until autumn there is nothing above ground to show where the corms are, and an unmarked bed gets planted over, walked on, or watered. If you lifted, record the count in each size grade and the date they went into storage. That grade count is the cleanest measure of whether the planting is gaining or losing ground year on year.