Don't feel bad nanner- i've done something similar before. Yes, as long as the bulb looks good and firm it should resprout. They really are pretty carefree. if you hadn't rescued it from the compost it probably would have sprouted out there. They are hardy in this area- at least most of them are.

I have several of the smaller, colored, hybrids in the ground - they come back pretty reliably as far as being there. I have to admit that I didn't water this summer as much as I should/could have (I am on a well, but....), so the blooms weren't great. However, considering the size of the bulbs (corms, tubers, ?) when planted and when I dug one up this spring, forgetting that there already WAS something in that spot, they are obviously thriving. With some extra mulching, I would think that yours would do the same in the ground. Of course, if you LIKE them in pots, you can also do that with them...., but I would protect them from hard freezes, whether in an unheated shed/garage or in your greenhouse.

While the un-improved, plain white one will grow in water - and probably not like to be in freezing water - they would also grow as a weed in sandy soil in San Francisco (where you had BETTER want them where you planted them, because you would only with assiduous efforts get all the bits of root, and thus all the sprouts, out of the soil after several years if you changed your mind about location) - the other, colored, hybrids, can thrive in drier conditions, but don't like to be soggy.

You'd be surprised what I find in my compost pile! Anyway, when I stumble upon a calla bulb this time of year I usually brush as much of the soil off of it and let it sit out and dry (in the shade) and then store it inside the house for the winter and plant it outside the following spring. They may not survive outdoors in a pot unless it is large and in a sheltered place. They are pretty reliable in the ground though. Still, I wouldn't risk it at this point. I usually store them inside in a pot filled with peat moss or dried sphagnum or dry spanish moss. They can rot if kept in moist soil while they are dormant (not sure why, since they survive outside in moist soil all winter...)

Thanks one more time John!! I appreciate the advice!! :-)

My regular, white calla lily lives in the waterfall year round. I've seen it encased in ice and it just grows bigger and wider and I divide, divide, divide. It's tough.

I have a pink one in the ground year round. It's right in front of the stone foundation with a full southern exposure in a protected corner (no frost in winter).