sadly... round up...

I'm down in Texas....I've had callas in full sun for the last few years and the folliage looks great all summer long. I even planted some especially this year to camouflage the ugly cement well in the front yard.

Since your plant was forced to bloom for Mother's Day it may be ready to rest. But if keep warm the hardy calla's do not go dormant. It's hard to tell which variety you have. Did it have a small flower and lanced shaped leaves or big flower with heart shaped leaves? Here is a link to the two different kind. Once you know which variety you have I can answer your question better. In the meantime repot it in a 12in diameter pot with fast draining soil. They love a lot a water but do not like to be in standing water or soggy. Did yours come with a plastic sleve over the pot? These will hold water. Always remove the sleve. Most of these calla below are not hardy. The flowers are smaller and leaves are smaller. http://www.pacificcallas.com/Varieties.htm You will find lots of information on this site about how to care for them. Here is a link that might be useful: hardy calla

There are several different leaf shapes. Remove the yellow leaf at once! Use some liquid calcium. Hope the leaf is just not drying out very quickly. Actually, by the time you read this, if your plant has not become a puddle of clear watery goo my alarm is just a false alarm. There is a disease called Rot that will destroy a calla in a matter of hours and presents like that. I lost over 300 callas in two beds in 3 days and there was nothing to do but sit and cry. In any case ALWAYS use a fertilizer with calcium. Bone Meal has about 15% by weight but it isn't all available. A good bulb fertilizer should have a high percentage of calcium. If your plant has bloomed, it will need a rest in order to produce new flowers. Set it to one side and allow it to dry out. Don't fertilize and keep it cool. After about 6 weeks, water, fertilize and let it have more light and warmth. It should set blooms in a short time. The blooms will likely be white. I expect it is Zantedeschia aethiopica. Outdoors, it does will as a bog plant or a marginal pond plant as that is how the original grows in South Africa. There are many cultivars. Sandy