Daniel Gill, Merrill, Thomas A.
By Dan Gill
LSU AgCenter Horticulturist
Caladiums are among the most reliable summer bedding plants for providing color in shady areas. They stay attractive despite the intense heat of summer and are rarely bothered by insects or disease.
By the end of September or beginning of October, however, they reach the end of their growing season and begin to decline in appearance.
Since these plants grow from perennial tubers, now is the time to decide what to do. The choices actually are a little more complicated than to dig or not to dig. Your options include pulling them up and throwing them away, leaving the tubers in the ground with the idea they will sprout again next year or digging them up, storing the tubers and planting them again next year.
Caladiums tolerate heavy shade and even do reasonably well in full sun (with proper selection of cultivar). They are at their best, though, when planted where they receive part-shade to part-sun in evenly moist beds enriched with organic matter.
If you have provided your caladiums with the growing conditions they prefer, your caladiums should have produced nice sized tubers by this time (as big or bigger than the ones you planted). These tubers can be used to grow caladiums next year – whether you leave them in the ground or you dig them up, store them and replant later on.
Where the growing conditions were not ideal, particularly if they were growing in heavy shade or dry conditions, the tubers may be too small to perform well next year (The tubers will be much smaller than what you originally planted). If that’s the case, you may choose to discard them and purchase new tubers next year.
If the bed where the caladiums are planted will stay relatively undisturbed, you may simply leave the caladium tubers in the ground. Since the ground generally does not freeze in Louisiana during the winter, the tubers should survive the cold and come back up next year. But it would be a good idea to keep the area mulched this winter to protect the tubers just in case it is unusually cold. Just keep in mind that plantings in northern Louisiana are more at risk of unusually severe cold than those in the southern part of the state.
A bed that is not well drained and tends to stay wet over the winter may cause the tubers to rot. Caladiums enjoy abundant moisture when they are growing but prefer to be dryer when dormant. If the area where the caladiums are growing tends to stay wet for extended periods, that can be problem, and it would be best to dig and store them.
If you intend to replant the area with cool-season bedding plants, such as pansies, the tubers also should be lifted and removed to allow you to do bed preparation for the new bedding plants.
Caladiums should be dug when many of the leaves have turned yellow and the foliage looks "tired" and begins to fall over. Do not wait for all of the foliage to turn completely brown and disappear, or it will be hard to find the tubers. Use a shovel or a garden fork to lift the tubers – being careful not to damage them. Leave the foliage attached to the tubers, shake and brush off most of the soil and lay them out in a dry location where they will be sheltered from rain (in a garage, under a carport or in a store room).
Allow the foliage to dry for 10 days to 14 days – until it is tan and papery in appearance. At that time the foliage will easily separate from the tubers leaving a cleanly healed scar.
The tubers can then be cleaned by washing in water to remove any remaining soil adhering to them. But unless there is a large amount of soil clinging to them, washing usually is optional. If you do wash them, however, they should be air-dried in a well ventilated place for several days, so all the moisture will have evaporated from the surface of the tubers before storage.
When dry, the tubers are ready for storing over the winter. Throw out any tubers that appear to be rotten or that have soft spots. Tubers you may have accidentally damaged when digging them can be saved if they have healed well and feel solid.
Since gardeners sometimes have a hard time deciding which end is up when planting caladium tubers, if you like, use a felt-tipped pen to mark the top while it is easy to see where the leaves were removed. That might save some confusion next spring.
Place the healthy tubers in an old nylon stocking, a mesh bag (such as an onion sack), a paper bag or cardboard box. The idea is that the container should be able to "breathe." Do not store the tubers in a plastic bag or airtight container, because that may lead to rotting. Make sure you keep the tubers indoors where temperatures will stay at about 70 degrees F or above.
Remember that with poor growing conditions, particularly in areas of heavy shade, caladiums produce small, weak tubers that may not return well either left in the ground or dug and stored. Under the right circumstances and with proper care, however, the tubers you planted this year can provide a beautiful display again next year.
Get It Growing is a weekly feature on home lawn and garden topics prepared by experts in the LSU AgCenter. For more information on such topics, contact your parish LSU AgCenter Extension office or visit our Web site at www.lsuagcenter.com. A wide range of publications and a variety of other resources are available.