Question
QUESTION: My daughter gave me a beautiful potted white cala lily for Mothers day. I would love to plant it outside so it can come back each year. Question I have is the information spike that came with the plant says "full sunlight" and shows a 60-65 degree temp range. I am not sure what that means. We live in Chicago so the winters are cold and lasting much longer than I remember in my younger years. It is almost mid June and some nights I still have my heat on. That said, is it safe to plant in the ground in this climate. If not, can I put the pot outside until fall/winter?

ANSWER: Hi Sheryl-Jones,
Thanx for your question.  In the Chicago area, you can safely plant the calla lily outdoors in late May.  The plant however, is not hardy north of Zone 8, Zone 7 for the large white Aethiopica type.  After the first frost has killed back the foliage, dig up the rhizome and keep it in dark, dry, cool basement and replant in the spring after ground temperatures are 65F and above.  You could keep it in a pot outdoors also, which might be easier if you don't want to dig up and store.  This way, you could just move the pot indoors to the basement for the winter while the rhizome is dormant.  I hope this helps.
Tom

---------- FOLLOW-UP ----------

QUESTION: Thanks for the answer. Follow up questions is: Do you know how I can find out what Zone 7 or 8 covers? I am in Chicago Il. Also if I put it outside in a pot..should I transplant it to a larger pot than what it came in ? Last but not least, if I keep it in a pot and bring it in in fall after first frost..do I cut it down or back? Thanks so much!!

Answer
Hi Sheryl-Jones,
Thanx for the followup.  Chicago is in USDA Zone 5 so you are considerably colder than the limit for calla lilies Zone 7 starts in the south like Oklahoma, Tennessee, Arkansas.  Zone 8 is Much of Texas and much of the Deep South parts of Arizona, California and Oregon.  Zone 5 stretches across the mid-Northern tier of the U.S. northern Kansas, Nebraska, Colorado, Iowa, Illinois, Indiana, Ohio, etc.

Here's a link
http://www.usna.usda.gov/Hardzone/ushzmap.html

Yes, I would transplant to a larger plant but make sure you can easily handle the pot.  No one wants to handle a heavy, bulky pot at the end of a growing season.  The first frost will kill back the foliage.  Don't worry.  The plant is still alive.  Bring the pot indoors and keep it in a dark, dry, cool basement where it is not warm but not freezing either.  The rhizome will go dormant until you bring the pot out in the spring.  You can cut the wilted foliage off an inch or so above the soil level afte the frost has killed it back.  I hope this helps.
Tom