Crinum are a species of lily from the Amaryllidaceae family. These large, showy lilies are usually variegated white and pink. Most have at least some white in their coloring, which is where the name crinum (white lily) originated. Crinum plants can reach 5 feet tall and are one of the hardiest lilies. Crinums require only basic cultivation.
Crinums thrive in US Department of Agriculture hardiness growing zones 8b through 11. These lilies are native to tropical areas throughout the world, but they can survive the occasional frost in zones 8b and 9. A compost mulch in early winter will help protect and feed the crinum.
Crinums grow best if exposed to full sunlight, which is defined as a minimum of 6 hours of sunlight per day. Eight to 12 hours is even better. Some species will grow in partial shade, but most prefer full sunlight. If you are going to plant crinums under a tree, choose a species that will grow well in partial shade, such as C. acaule.
Crinum lilies need nutrient-rich soil. Amend your soil with organic material down to a foot before planting. Otherwise, these plants will tolerate pretty much any type of soil, from slightly acidic to slightly alkaline, sandy or clay. Some species, such as C. moorei, will tolerate dry soil, but most prefer moist soil. C. campanulatum actually needs to be grown submerged in water.
All crinums are heavy feeders and will benefit from regular feeds as well as organic mulch. Fertilize once a month with food made for flowering bulbs during the plant's first year. After that, fertilize once in midsummer and use an organic compost to mulch the plant in the winter.
Water first-year crinums at least once a week during the growing season if it does not rain. Try to avoid wetting the leaves, as this can lead to leaf spot, a fungal disease. Once the flower is established (year 2 and beyond), you may not have to water it at all save for hot, extended periods of drought.