Hm, 40 degrees might stress some plants for overwintering, but.. I'd certainly try Pelargoniums and Heliotrope.

Melanie :)

Salvias, snapdragons, calibrachoa, zonal geraniums, diascias, bracteantha, nemesias, and gerbera daisies.

How do you winter over impatiens??

Vera - annuals are annuals and cannot be perennial, no matter where they are grown. Perennials are plants that are capable of completing at least three annual growth cycles. Where they are grown doesn't change them from perennial to annual. In colder zones e.g., impatiens are simply perennials that are often treated as annuals because they lack the cold-hardiness to survive in northern latitudes.

Al

The same is true with coleus being a perennial that is treated in colder zones as a annual. Interesting that they are both commonly known to be easily propigated in colder climits by taking cuttings at the end of the season and rooting them in water. Hmmmmmmmmm

I'm sorry Tapla but that is NOT true! But you are right that a 'true' annual grows, flowers, sets seed and dies. The cycle can be prolonged is not allowed to set seed. Biennials can also be tricked into performing as perennials given they are not allowed to set seed as well. Most things we call annual are actually perennials that bloom the first year but could not make it thru a zone 3 (or whatever) winter. Example What is an annual in zone 4 and 5 could be perennial in zone 6 or above.
Some folks grow Lavender 'Lady' as an annual below zone 5 because it is a first year blooming perennial. Here it grows as a perennial. Most people throw out their Poinsettia after the holidays even though they too are a perennial that can grow too HUGE proportions in Mexico (an like climates). I can only grow certain plants as annuals here (Pineapple Sage)in zone 5b-6a for instance but someone in zone 8 and above can grow it as a perennial.
I have had the same Coleus going on 3 years as well as a few peppers. As a matter of fact at school (I'm a greenhouse/nursery student) we have Coleus, peppers, Begonia, etc...that are kept as stock plants that have been in the greenhouse for years...it is from these that all our new cuttings are taken for spring annual bedding plant sales.
What else is perennial that most grow as annuals? Well lets see to name a few:
Hibiscus
Lantana
Geranium
Fuchsia
Dahlia
Canna
Crocosmia
Glad's
Capsicum sp.
Impatiens
Marigold
Salvia sp. (many)
Dianthus
Passion Flower (Passiflora)

Vera

That's what I said. ;o)

Al

Pardon! I missed that part since the question was about annuals that are actually 'tender perennials'...and since I misread, it seemed like you were saying NO plant called an annual is actually a perennial :)
It was a LONG day w/ my poor eyes on the blackboard LOL!

Vera

I just want to thank everyone who responded to my question. I've been filling my greenhouse with tender perennials these last couple of weeks. There's a nursery near me selling them for $.10 each, so at that price I can afford to experiment. I'll report back in the spring re: which ones did well.

Oh, and to answer Vera's question, I'll be using supplementary heat to keep the greenhouse at or above 40. I'd like to keep it warmer, but I don't want to spend a fortune on heating.

40 should be fine...plants will just stay dormant.
Look forward to your spring update :)

Vera

Vera, how do you overwinter Lantana? I have a cold frame and would like to try to salvage mine, as they were just beautiful this year.

Karen