The Magic of Rain Lilies
The common name rain lily comes from this plant’s tendency to bloom after a good soaking from Mother Nature. They are native to tropical and semi-tropical regions of the Americas. There are 3 genera commonly known as rain lilies – Zephyranthes, Habranthus, and Cooperia. Rain lilies are a perennial bulb with a hardiness of USDA Zones 7 to 11 for most species. They come in various colors, mostly ranging from pinks, yellows, and whites and new colors are popping up through hybridizing and breeding all the time. Although the common name would suggest that they are in the Liliaceae (lily) family, they actually fall under Amaryllidaceae.
Rain lilies are often grown in containers where they can be placed on a front porch or around a deck and will reward all season long. I have found that if grown in containers, they seem to prefer being slightly crowded and even somewhat pot-bound. They also look great along a pathway or in the front of a sunny border and are often used in rock gardens. To get the finest show, Rain lilies look best planted in masses. Most Rain lilies will bloom several times a season, usually after a good downpour.
If you live in a zone where Rain lilies are not hardy they are easy to overwinter. When it starts getting cooler, simply bring them indoors (either the container or, if planted, the dug up plants – if possible give them a quick potting) and keep them dry all winter, then set them outside again in the spring. You can pull off the foliage as it dies to keep them clean. You may want to either add soil or rough the edges of the pot prior to setting them outside if the soil has shrunk over the winter.
Rain lilies grow best in full sun to partial shade. They prefer to be kept evenly moist but can tolerate periodic dry spells without problem. During summer months use a well-balanced fertilizer (either liquid or slow release). The bulbs produce offsets which can be divided and planted in spring or you can sow seeds if you wish. If you are collecting seeds, sow right away before they dry as they tend to lose the ability to germinate and may take extra time to do so. Rain lilies are very gardener-friendly as they have no serious pest or disease issues. I have had problems with mealy bugs, however, but that is because I start watering them earlier in the season than normal and I keep them in the greenhouse for a fuller plant come spring. Be aware that all parts of the plant can be toxic if ingested.
After reading this, you may be eager to see some Rain lilies for yourself, so please stop by the Ripley Garden at the Smithsonian Institution this summer and enjoy their beauty. Some of the ones we display are Zephyranthes flavissima, Habranthus robustus ‘Russell Manning’, Habranthus texanus, and Zephyranthes candida.
-Matt Fleming, Smithsonian Gardens horticulturist