(Rain lily, Rainflower, Valles yellow rain lily, Zephyr lily)
These Mexican native bulbs actually offer demanding gardeners flowers on demand. They produce strappy foliage to 12 inches tall and clusters of buttery-yellow, starry, crocus-like blossoms two to three days after every rain in summer and early autumn. Or, if it doesn't rain, simply water and fertilize three days prior to your intended display, and the moisture will prompt the flowers to appear, hence the common name, rainflower. These bulbs are widely adaptable to diverse soil conditions, and may be grown in full sun to partial shade, but they prefer some shade.