Why do deserts sometimes bloom after heavy rainfall?

Deserts bloom after heavy rainfall primarily due to the presence of ephemeral plants, which have evolved to survive long, arid periods as dormant, resistant seeds within the soil seed bank.21

When significant, well-timed rainfall occurs, it provides the necessary moisture to trigger germination. In some species, this process is regulated by seed coats that contain growth inhibitors, which must be washed away by a substantial amount of water to ensure the plant does not sprout after only a brief, insufficient shower.213

Once triggered, these plants grow rapidly, flowering and completing their entire reproductive cycle within a few weeks before the soil dries out and harsh conditions return. This strategy allows them to take maximal advantage of infrequent wet periods. In rare instances, when conditions are exceptionally favorable, a large number of these seeds germinate simultaneously, resulting in a spectacular phenomenon known as a super bloom.142