The fruiting bodies of morels have been observed growing as much as 1/2-inch taller over the course of three days, according to The Great Morel. Under ideal conditions, the sclerotia forms primordia within 2 weeks, and the fruiting bodies take 12 to 15 days to mature from the primordia, according to Thomas J. Volk of the University of Wisconsin.
The Farm reports that the spores of morels can send out visible growths within a few hours of being placed in ideal conditions and that it takes four to six weeks for morel sclerotia to develop from mycelia.
The life cycle of the morel mushroom is complicated, as explained by Tom Volk. Spores released by the fruiting bodies form thread-like structures called mycelia. The mycelia grow continuously until growing conditions become harsh, and at that point they develop into sclerotia. Sclerotia are small, hard lumps that lie dormant until conditions for growth improve. Once stimulated to regrow, sclerotia can either grow more mycelia or develop primordia that grow into the fruiting bodies. The decision depends on the growing conditions. Certain areas have been documented where the fungus exists as mycelia during the summer and sclerotia during the winter for 80 to 100 years at a time before sending up fruiting bodies in response to a forest fire. The fruiting bodies are what are commonly referred to as the "morel mushroom," which is a prized delicacy in the kitchen.