I planted some in the spring of last year, and they didn't come back from the winter.

I live close to Augusta, zone 8.

So I would say, you could try it, but they didn't come back for me in zone 8.

I planted 4 varieties last year, green goddess, nightlife, dark eyes, and a yellow one. All came back great doubling last years size( this May - late breaking dormancy) with the exception of the yellow. The tags say zone 8 minimum 20 degrees. I'm boarder zone 7b-8 and it definitely was colder then 20 many times this winter....

So, I would for sure try! Oh, left in ground.

Thanks for the replies. Lorabell, did you add extra mulch? I use pine needles; easier for me to handle. But I thought I might cover them with pine park mulch to add some protection.

I did a layer of cypress mulch over my beds last Fall ( cheap)

Come to think about it, the yellow one that didn't make it was in an area I didn't mulch! I also was impatient this Spring when I didn't see them coming up and might have bothered the area of the yellow one and planted something else....lots of lessons for me here! First year of growing them.

If you're looking for cultivars to experiment with outside, 'Edge of Night' has returned for me for several years in Durham (zone 7a), including after last winter's single digits. No mulch, just whatever leaves fell off the trees. There's good drainage in that area of the garden, which has probably helped it survive winter.

They are well worth the effort.

I live in a USzone 4 (or my Canadian Zone 5). Much to my surprise a forgotten calla lily survived winter in my yard. So I think its fine for your zone but do protect it well. I think the key was that mine was well insulated under a heavy cover of snow - so when the weather dipped or warmed up, temperatures remained steady. I've also seen cannas survive winter here and these are tropical plants (zone 11).

I guess you never know how nature handles things, but I will definitely mulch!

I live about 30 miles east of Charlotte, NC and have about 15 callas. I have had most of them for about 10-14 years. After I planted them, I mulched them but now a lot of them do not have mulch covering them and they come back each year. Some years, there might be one of two that don't flower but most years they all flower. Good luck with your plants.

Im thinking that this plant is much more hardier than what we thought and perhaps the suppliers are playing it safe by saying its an annual for my zone..

I was told that the breeders mixed different species of Calla lilies to get all the different sizes and colors. Some of the original species are hardier than others and some live in regular garden soil conditions while others like wet soil. So, some colors are going to be hardier in some gardens and unless you know the genetic makeup of the variety you want you won't know how it will perform. There are dozens of white or yellow forms and each one has a different heritage so just because they are the same color doesn't mean they have the same characteristics or are the same plant. Most of them come back for me eventually but some don't poke their noses out of the soil until now!