Saffron bulbs multiply, although the term “bulb” is botanically inaccurate for this plant. Saffron, derived from the dried stigmas of the Crocus sativus flower, is a sterile triploid plant unable to reproduce by seed. Therefore, cultivation relies entirely on the plant’s natural ability to multiply its underground storage organs, ensuring the continuous production of the valuable spice.
Defining the Saffron Corm
What is often called a saffron bulb is actually a corm, a significant botanical distinction. Unlike a true bulb (like an onion) made of fleshy, layered leaves, the corm is a solid, swollen underground stem base. This tissue serves as a storage unit, packing starches and energy reserves to fuel the plant’s growth cycle.
The corm’s structure, typically globular and protected by a fibrous outer tunic, is solely for propagation and survival. It is the foundation from which the leaves sprout and the autumn-blooming purple flowers emerge. The size of the corm is an important factor in cultivation, as a larger corm (often weighing over 10 grams) correlates with higher yields and increased multiplication potential.
The Mechanism of Corm Renewal and Multiplication
Saffron’s reproductive strategy involves complete annual turnover, where the parent corm sacrifices itself to create new individuals. Once planted in late summer, the parent corm uses stored energy to produce leaves and flowers in the autumn. During the growing season, which extends through the spring, the mother corm begins to shrink as its resources are depleted.
This energy is redirected to form new, smaller daughter corms (cormels) that grow around the base of the dying parent. The growth rate of these daughter corms increases significantly in late winter and early spring, reaching maximum biomass as the leaves begin to senesce. The parent corm is fully consumed by the end of the season, leaving behind a cluster of daughter corms that become the next generation of flowering plants.
A single mother corm typically produces multiple daughter corms, often yielding 2 to 5 new corms per cycle. Larger mother corms tend to produce more and heavier daughter corms. This is important because the size of the daughter corm directly influences the likelihood of flowering the following year. This strictly vegetative propagation allows the sterile Crocus sativus to continue its life cycle and provide a sustainable saffron harvest.
Managing Corm Division and Density
The natural multiplication of saffron corms necessitates regular intervention to maintain high spice yields. As corms reproduce year after year, the planting bed becomes increasingly crowded. This high-density environment leads to intense competition for nutrients, water, and light, causing a decline in flower production and reducing the size of new daughter corms.
To prevent this drop in productivity, “lifting” or dividing the corms is required, typically every three to five years. This action is best performed after the foliage has died back and the corms have entered summer dormancy, usually in late spring or early summer. The corms are dug up, separated from one another, and checked for disease.
Once divided, the corms must be replanted at a proper density to ensure optimal future growth and multiplication. Recommended planting densities vary, but a common range is 6 to 12 corms per square foot, or 3 to 4 inches apart. This careful management ensures each new corm has sufficient space and resources to mature into a large, flower-producing size, sustaining the saffron harvest.