If you ask an expert gardener how to propagate crocus, you will probably be told that humans don’t propagate crocuses. Crocuses propagate themselves.
How They Grow
Crocuses grow from bulb-like modified stems called corms, which are fleshy chunks of stored nutrients. Each corm has a bud or tip on its top, from which the leaves and flowers will sprout. Over the course of a growing season the nutrients in a corm are used up and the corm shrivels. At the same time, however, a large new corm is forming below the existing one, which will sprout the following year’s plant. Offsets called cormels grow around the edges of the new corm; each cormel will also sprout a plant the following year, although these plants may not bloom until their second year.
Allow Crocuses to Self-Propagate
If you simply want to see an ever-increasing patch of crocuses in the same location, all you need to do is keep the surrounding soil adequately watered and fertilized. After the crocuses are done blooming, remove the dead blossoms but allow the leaves to grow and eventually wither naturally. That is how the plant collects and stores nutrients for the new corm and cormels. Over the course of three to four years a single crocus corm will produce as many as 30 cormels and new corms.
If you want to move some of your crocuses to a new location, lift the corms from the soil using a garden fork after the first hard frost. Remove the old spent corm and the new cormels. Replant the new corm in the same location. Plant the cormels in a nursery bed where they can grow to blooming size. The following fall dig them up–you will be amazed at how they have grown. You can then plant them wherever you wish to have new crocuses the next spring.