A 'super bloom' erupts in the Mojave Desert when winter rainfall exceeds 15 centimeters.

A super bloom is a rare botanical phenomenon in California and Arizona deserts where an unusually high proportion of wildflowers germinate and blossom at the same time. In the Mojave Desert, this typically requires at least 15 centimeters of rain during the winter months of October through February. This amount is nearly three times the region's annual average of 5 to 10 centimeters.The seeds of desert annuals like the California Poppy (Eschscholzia californica) and Desert Lupine possess a thick waxy coating. This coating acts as a natural timer, ensuring the seeds only sprout when enough water has soaked the soil to wash away chemical inhibitors. Without this mechanism, seeds might sprout after a light rain and quickly wither in the heat.The 2005 and 2016 super blooms were so intense that NASA's Operational Land Imager (OLI) on the Landsat 8 satellite captured the transformation from orbit. These events require a specific sequence of deep soaking rains followed by a mild spring without drying winds or extreme heat. Researchers at the University of California, Davis, note that while these events are spectacular, invasive grasses are increasingly competing with native flowers for these vital water resources.Climate change is also altering the frequency of these events by creating more volatile weather patterns. While some years see extreme drought, others see atmospheric rivers that provide the necessary deluge. Botanists track these events closely because they provide a massive, albeit temporary, boost to local pollinator populations like the endangered Quino checkerspot butterfly.