Because common callas (Zantedeschia aethiopica) can thrive in up to a foot of water, they would make a good gift for the relative who always overwaters plants. These ones don’t mind soggy soil, and will even revel in it. They aren’t picky about illumination either and can get by on partial sunlight or even bright indirect light.
The downside is that the plants are highly toxic, so you’ll want to avoid them if you have pets or young children prone to mouthing greenery. Callas also tend to drip sticky moisture from the tips of their leaves, so don’t place them on your antique sideboard! Since they can grow 2 to 3 feet tall indoors—and probably at least as wide—they won’t fit on a narrow windowsill either.
In mid-autumn, pot the tubers in a mix of two parts acidic organic potting soil and 1 part sand. Unlike the more round tubers of other callas, those of Zantedeschia aethiopica tend to be lumpy and oblong. In Forcing, Etc., Katherine Whiteside recommends that you position them vertically in the soil with their growing tips up and the top one just peeking above that soil.
Because the plants do get large, it’s best to use a pot about 10 to 12 inches in diameter. How many tubers you can fit into it will depend on the size of those tubers. If they are over 2 inches in diameter, insert only one per pot. Should they be only about 1 1/4 to 1 1/2 inches across instead, you probably can squeeze in three, evenly spaced.
Keep the soil lightly damp until the tubers begin to sprout, which can take two weeks to two months. From that point on, it’s important that the soil remains evenly moist, since the plants may begin to drop into dormancy if they dry out completely. You can provide that moisture by setting the pot in a pot saucer and keeping that saucer full of water.
Feed the plants about once every three weeks with plant food at half strength. They should begin to bloom about four months after the tubers were planted. In other words, if you potted them up in mid-October, expect flowers around Valentine’s Day.
Once the plants stop blooming in mid-spring, cease fertilizing them, but continue to water them until mid-summer. At that time, stop watering them also and allow their foliage to die back to the tubers. Store the pot in a warm, dark location for two or three months until about the same time you planted the “lilies” the previous autumn. Then you can re-pot them in fresh soil and start the process all over again.
Since common callas tend to be more evergreen than other types, it’s sometimes hard to convince them to go dormant. In that case, you might want to follow Tovah Martin’s example. In The Unexpected Houseplant, she reports that she keeps her callas growing all year, but cuts off their leaves just before she brings the plants indoors in autumn. If the soil hasn’t been allowed to dry out, new foliage should sprout quickly.
Photos: The thumbnail photo is by henryr10 and the tuber photo by chris_lcf530, both from the Dave's Garden PlantFiles. The cropped and enhanced flowers photo is by Manfred Heyde, courtesy of Wikimedia Commons and this license. The antique image is by M. E. Eaton from Addisonia, Vol. 12, courtesy of plantillustrations.org.