After 6-8 months of growing when summer ends, your colorful caladiums will begin to look tired, stringy and bedraggled. When foliage begins to die back, they're ready for a nap. But if their bulbs are stored properly, they'll winter just fine and you can replant them next year. Lift your bulbs before the first predicted frost from August to October, depending upon your location. Caladiums can't tolerate freezing.
Cut the caladium's browning foliage back to about 6 inches tall. You'll use that stub as a handle when removing the bulb from the ground. It's also a good idea to leave enough foliage intact so that you'll be able to identify its variety after digging, if necessary.
Grasp the stub in one hand and drive a trowel vertically into the soil several inches away. Start digging a circle around the bulb, scooting the trowel blade underneath it. Gently tug on the bulb as you loosen the soil around it. You can slip a hand under it to help pull it upward. Take care not to nick or cut the bulb with the trowel, since damage can cause the bulb to rot during storage.
Use your fingers to scratch around in the hole a bit. You may find some small bulbs that have developed from the mother plant but have become dislodged. These are as viable as any remaining on the mother bulb.
Spread the caladium bulbs out in a cool, dry location and allow them to dry for about a week. Don't remove the soil from them until they're through drying.
Brush dry soil from the bulbs and cut or pull any remaining foliage off. Examine them for signs of rot or damage, and discard any that aren't perfect. You can divide them with a sharp knife at this point, if desired. Any bulbs that you cut will require an additional 2-3 days drying time for the wounds to heal. Also, keep in mind that second year plants will probably be smaller than they were this year. So most gardeners prefer to leave new tubers on the original for the sake of producing more abundant displays on each plant next year.
Dust caladium bulbs with powdered fungicide, if desired. Layer a cardboard box 3-4 inches deep with Vermiculite or dry peat moss. Arrange the bulbs on the surface so that they aren't touching each other. Add another 3-4 inch deep layer of substrate. You can continue to add layers of bulbs and medium as desired. Store the caladiums in a well ventilated area which doesn't drop below 50 degrees F until you're ready to plant them back outside in early May.