- Light: Hymenocallis like bright light, but not necessarily full sun. When the bulb is first planted, they need less light but as growth resumes and the plant becomes larger and goes into flowering, you can move it steadily into brighter light.
- Water: During the winter dormancy, the bulb should be stored in sawdust or a bag of dry peat. In the later winter or early spring, plant the bulb in moist soil and keep it moderately warm (about 65˚F) until growth emerges, watering steadily but not overwatering. Water-logged soil will likely result in a rotting bulb. As the flowers and leaves die back in the fall, reduce water until you can pull the bulb up again.
- Soil: Use a fast-draining potting soil with plenty of organic material.
- Fertilizer: Feed with a weak liquid fertilizer throughout the growing season.
Hymenocallis are typically bought either as bare bulbs or as potted plants already. They can be propagated from bulbs, as older plants will eventually send out offshoots that can be carefully separated from the parent bulb and potted up individually.
Because these are bulbs, they will require annual repotting in a fresh container with new potting soil. These are slightly larger than many varieties of lily, so you can safely put them in larger containers with a pretty ground cover around the base of the plant. At the end of the season, discard the old soil and move the bulb to its winter home (probably a bag filled with sawdust, wood shavings or dried peat). You can store the bulb in a cool cellar or garage at about 55˚F until it's time to pot it up again.
The most common variety is the H. narcissiflora, which features a 3-foot tall flower stalk and enormous flowers. Somewhat less common is the Hymenocallis x festalis, which is slightly smaller but has stark white blooms. Finally, the H. speciosa is relatively rare. This species does not go into a winter dormancy and can be overwintered in its original container.
Hymenocallis are definitely novelty plants for indoors. It's fun to grow them in the middle of a larger container with a low-growing, attractive ground cover. Its unassuming leaves will attract little attention until its huge flowers erupt in a show display over the container. Better yet, the flowers themselves are subtly fragrant. They are also not terribly difficult to grow: simply provide warmth, steady but not overbearing moisture, and decent light and your plant will thrive through the summer months. Some people find overwintering to be difficult for indoor bulbs—no matter, if you're not the type to dig up and store bulbs, just discard the bulb and buy a new specimen next spring. Hymenocallis are vulnerable to pests including aphids, mealy bugs, scale, and white fly. If possible, identify the infestation as early as possible and treat with the least toxic option.
These are really cool plants. The Hymenocallis is a member of the lily family, so grows like other lilies from an underground bulb. Most varieties of Hymenocallis go into dormancy in the winter, so there is the question of overwintering bulbs and replanting them in the spring. Once they've begun growing, however, a loose crown of strap-like leaves emerges from the bulb. The leaves themselves aren't very spectacular until the flowers emerge. The typical Hymenocallis features huge and very unusual flowers on tall stems. The flowers are beautifully fragrant and definitely eye-stopping. It's worth noting, however, that the leaves of this plant are poisonous, so if you have a child or pet that's likely to put the leaves in their mouth, this is not a good option.