Late last year, I stopped by a favorite nursery and binged on plants for which I did not have a place prepared in the garden. Among the must-haves that found their way into my cart were Habranthus robustus, the nodding rain lily.

Zephyranthes sp. and Habranthus sp. are two genera commonly known as rain lilies, because they come into flower after summer rainstorms. Interestingly, they don’t respond in the same way to a shower from the hose or watering can–even if the water comes from a rain barrel. I am fascinated to know how these plants know the difference between the water sources. I have read a suggestion that it’s to do with nitrogen in the rainwater fixed by lightning, but they bloom after storms without lightning as well.

I am not sure why it’s called nodding rain lily–I didn’t observe the blooms nodding downward to any extent, but perhaps mine were duds. The position of the bloom, though, is one way to tell the genera apart: Zephyranthes species’ blooms tend to face upward, while Habranthus species’ blooms face outward, like those of their relative, the amaryllis.

The bulbs begin blooming in late summer, when little else shows up, and will often multiply steadily if planted in a happy spot. Unfortunately, I think mine may have been lost to last winter’s polar vortex. Plant Delights Nursery and Brent and Becky’s Bulbs carry lots of these fascinating plants, which are hardy between USDA Zones 7-10. I have read that Zephyranthes citrina is hardy to Zone 5. I’m keen to repopulate my garden with them all, but I may have to wait until next spring. I hear that another polar vortex may be in future this winter.