This rain lily is a small un-imposing plant that produces big beautiful flowers periodically throughout the summer depending on rainfall patterns.
Several of the zephyr lilies (genus Zephyranthes) are called "rain lily", but this one most deserves that name: Zephyranthes grandiflora blooms numerous times throughout the summer and autumn, always after a rain that follows a dry period. Atamasco lily (Z. atamasca), on the other hand, blooms only once each year, in the early spring. Other members of the genus bloom in spring or autumn only. Shortly after a summer rain, the rain lily produces a single maroon lipstick-like bud atop a hollow 7 in (17 cm) flowering stem, known technically as a "scape." Within a day or two the bud opens to produce a lovely rose-pink flower about 3 in (7.5 cm) long with six petals spreading about 3 in (7.5 cm) across. The flowers last a few days, closing up at night. The grasslike leaves that emerge from the underground bulb are strap shaped and about 10-12 in (25-30 cm) long.
Location Zephyranthes grandiflora is believed to have come originally from Central America, but no one knows exactly where - probably Mexico or Guatemala. Generations of sharing gardeners have spread the rain lily throughout the Deep South, and today rain lilies can be found in lawns and gardens even if the house that once stood there is little more than a memory and a crumbling chimney.
Grow potted rain lilies in a soil-based potting mix with extra sand added. They do best when crowded and slightly pot-bound. During the summer, fertilize every 3-4 weeks with a balanced fertilizer. Outdoors, rain lilies like a moist but well drained soil in full sun. Light: Grow rain lilies in full sun, or in part shade, especially a high shade from tall trees. Moisture: Rain lilies bloom after spring, summer and autumn rains. They can wait out a drought, but if you water freely after a dry period, you can induce them to bloom. Water potted plants infrequently in winter, and for rain lilies in the ground, don't supply supplementary water at all in the winter, as the bulbs need a rest. Hardiness: USDA Zones 8-11. Many references say that the rain lily is hardy only as far north as zone 10, but we in Florida's zone 8B have been growing rain lilies for decades without any winter protection. Farther north you will want to mulch the bulbs before freezing temperatures dominate, or lift them for indoor storage. Farther north still, you should grow them in pots that can be brought inside during winter. Propagation: The rain lily we have in cultivation is sterile and does not produce seeds. The bulbs, however, produce offsets which can be divided in spring. Set bulbs 1-2 in (2.5-5 cm) deep, and don't worry about crowding - they seem to like it!
Scatter colonies of rain lilies throughout the garden, among shrubs and even in the lawn for post-rain popup surprises of colorful flowers.
Rain lilies are often grown in pots on the porch or deck in summer where they flower gloriously after each rain. Crowd a dozen or so bulbs in an 8 in (20 cm) pot, and you will be rewarded several times a year with a spectacular show. In warm climates, use rain lilies along a walkway or at the front of a sunny border. They are often used in rock gardens. Rain lilies are really at their best, though, when clumped in large, irregular masses.
There are some 70 species of zephyr lilies, all from the New World tropics and subtropics. Zephyranthes grandiflora is sometimes marketed in the bulb trade under incorrect names, such as the Cuban Z. rosea, which actually has much smaller flowers, wider leaves and is considerably less frost hardy; or Z. robusta which is a synonym for the Brazilian Habranthus robustus, whose pale pink flowers, although a little smaller than those of the rain lily, are carried on taller scapes. It also is less hardy than Z. grandiflora.