Question
I am growing callas and caladium's from bulbs I found in a discount store. They are lovely and I would like to know how to winter over the bulbs as I live in southern New Hampshire and cannot bring the entire plant inside.

Answer
Clemson horticultural extension service (hgic.clemson.edu/factsheets/HGIC1160.htm) posts a simple technique for saving Caladiums.  They time this procedure in autumn before leaves have lost all their color.

"Spread [the tubers] out and allow them to dry for a week. Cut or pull the dry foliage from the tubers and remove all dry soil, then pack in dry peat moss or vermiculite for storage. Pack tubers so they do not touch each other. Store them where the temperature will not drop below 50 degrees F."

Clemson experts point out that each tuber includes a central bud and several smaller buds.  Most varieties produce one large middle bud and smaller buds attached. They are generally expected to grow a handful of colorful leaves if that middle bud is allowed to grow. Removing that middle bud in the center encourages the tuber to grow abundant numbers of lush leaves."

They also recommend you use the tip of a sharp knife to carefully pop out the middle bud.

They note: "Starting with new tubers each year may give better results since second year foliage is usually not as good as the first year. You may have better luck storing and regrowing tubers of white-foliaged caladiums than those of other types."  

Regrettably, I plead guilty to the less-is-more Caladiums school of gardening, as I have always (with a heavy heart) tossed spent Caladium tubers and re-ordered fresh ones in the spring - if I want to grow them again.  The overwintering routine is simply too, too high maintenance, especially given the Dahlias and orchids I tend through winter.  Caladiums are a lush breath of spring if you grow them indoors during the winter - the low light and beautiful leaves grow beautifully in any bright room, away from the direct sun.

By the way, don't put your Caladiums in the refrigerator for storage.  They will rot in a New York minute.  Keep them in a dry basement, a closet, even the attic - a non-freezing area of the garage will most likely be too cool since they need to be relatively warm, at least 60 degrees F, during the winter.  

Store them in cardboard shoe boxes resting in vermiculite.

In much warmer climates, as in South Florida and souther, Caladiums are replanted in the early summer, when the soil reaches 70 degrees, but in the Northeast, you should start them much earlier, as growth can be painfully slow.

Callas are another story.

Callas are left outside only in USDA Zones 8 and 9, where they are mulched with bark or straw before winter. The Dutch Gardens website posts the simple tips for keeping Callas for the winter (www.dutchgardens.com/on/demandware.store/Sites-DutchGardens-Site/default/Link-Page?id=5325&SC=):

"In colder areas, lift the rhizomes after first frost, clean off excess soil, let dry out of the direct sun for a few days, then store in a dry location that remains between 50 and 60 degrees F."

You replant these in the spring when all danger of frost has passed.

Overwintering is a tricky balancing act.  Even with your best shot, expect to be discouraged at least a few seasons over one problem or another.  Like anything else, practice makes perfect.  If you can keep at it, these overwintering rituals will be your routine in a few short years, with spring smiles to follow.  Good luck and let me know if you need clarification on any of the above.