Are you using "orange" generically to mean any citrus, or do you mean specifically a sweet orange that one eats out of hand? There are a few options for ornamentals or citrus to use in cooking (i.e. zest, juice). Check out this site: http://mckenzie-farms.com/index.htm

I believe there are some trifoliate hybrids that would do well in your area. Are you in New Mexico? You might do some research on Citranges, Citrandarins, Citrumelos, as well as some of the hardier Tangerine varieties (10-degree tangerine, Keraji Mandarin, Changsha, etc.) Have you noticed any other citrus in your area?

carlsmx_z8a_nm,
I am in zone 8. I am growing Satsuma mandarin, lemon, and grapefruit.
They are in containers and during this recent cold snap I brought them into the greenhouse for a couple of days. I have put them in the garage before.
So, I would be cautious about growing in the ground in zone 8.
There are a few people downtown where it's protected that are growing mandarins outside and they are doing great!
I bought mine from Four Winds. they have a hardiness chart on their web site.
Tom

I'm in NC 7b ... about 10 miles from 8a. I planted a Satsuma Kimbough this past spring and after a 17 F night, it's doing fine. I have many other citrus and hybrids in my greenhouse that I will plant out this spring.

I'm in Washington State... have had a Changsha and Meyer Lemon outside for about 4 years. The Meyer gets hit pretty hard in the winter, but the Changsha seems to be a real winner. Been down to 14f this winter and it's still looking good (my Valencia seems to have bought the farm though).

Hi, i don't know if i live in zone 8A or just zone 8, but oranges do well over here. it does get really cold some winters and the frosts seem to damage the oranges depending on how bad the temperature is. I know people have orange trees everywhere around here and despite a little die back on the new growth, the trees seem to be fine. We had about 4 days that droped down around 26and 27 and alot of plants died , but i havn't seen any dead citrus trees. My neighbors on both sides have citrus and they are fine, one of my neighbors tree, still has a bunch of oranges on it. They sure are good!

I'd recommend growing a satsuma on flying dragon rootstock protected as follows:
{{gwi:560934}}

Satsuma is the best tasting cold hardy citrus, seedless too.

Here is a link that might be useful: mrtexas

Cold Hardy Citrus field experiment.

http://www.walterreeves.com/uploads/pdf/coldcitrus.pdf

I have read all of these ccomments and not one has answered the persons question which is, do you know of a cold hardy variety orange that will survive in zone 8. Not satsumas, etc, but ORANGES. No other information. Thanks

i live in nc obx i had satusmas for 3 years outside unpro tected no broblem i give away trees and oranges

I didn't see the answer, sorry if I missed it. Both Valencia and Blood Oranges can be planted outdoors in zone 8 if you are willing to take a little extra care with them. They should be planted on the south or southeast side to protect them from the colder north winds.

Ps. If you have a local farmer's market that sells citrus you can grow trees from their seeds, since they are already in your zone they should be able to thrive there.