I thought very seriously about including one in my tropicalesque bed but upon closer investigation ultimately found that they are a very unattractive plant.
Go for it for the novelty but don't put it somewhere for public viewing :)

"a very unattractive plant"
I completely disagree with this.
Beautiful spring flowers, attractive autumn fruit, striking long thorns and deep green winter stems. What more could you want?
Certainly put it somewhere for public viewing - people are amazed to see 'oranges' growing in cold climates!

Here is a link that might be useful: Poncirus trifoliata

Agreed. They are gorgeous when they flower. Put the trees out front, let people pick them (trying to get free fruit without asking), they won't be back to get at your good stuff :P

Trifoliate orange is not a new plant. It has been around for a long time, and is used as rootstock for sweet oranges and mandarins. It is cold hardy to -15 degrees, and resistant to root rot and crown rot, which is why it makes a good rootstock. In colder climates, it is grown as an ornamental. It will lose it leaves in the winter, but the blossoms in the spring can be attractive. Watch out for the large thorns. The fruit is not tasty.

Here is a link that might be useful: What's Growing On?

Thanks for the replies and I agree it is an attractive tree I would want to show off. I just don't know if I have any more room in my yard for a tree! I will find somewhere!!

I don't think they will reach maximum size that far north.

I think the naked branches with the yellow/orange fruit in the fall is very ornamental.

People grow it here in the south for an ornamental, too! I especially like the Flying Dragon. It's hard to find in nurseries, though. But it has naturalized here and I see it in fields, along fencelines, out in the country a lot. Rishel, you're right, anyone who steals the fruit won't be back for more!!