I'm in Long Island. Have had Hens and checks outside for three years.But they're in a container and next to the houser,so I think its a slightly-warmer micro-climate.

Jean ,
Is your's the yellow flowering pear? There is a Purple Texas Cholla(Opuntia imbricata)that is hardy to zone 4 , hummers and butterflys love it .
Kareen

Here is a link that might be useful: Our pond and gardens

The June issue of Horticulture Magazine had an article about cactus that suggested these.

Escobaria vivipara(Coryphantha vivipara; beehive cactus) hardy to zone 4
Echinocereus reichenbachii subsp. baileyi (lace cactus)hardy to zone 5
Echinocereus triglochidiatus (claret cup hedgehog cactus) hardy to zone 5
Opuntia humifusa (prickly pear cactus)hardy to zone 4
Opuntia phaeacantha (purple-fruited prickly pear)hardy to zone 5
Cylindropuntia imbricata (cane cholla)hardy to zone 5

You may also want to check with the;

Cactus and Succulent Society of America
P.O. Box 2615, Parhump, NV 89041-2615
www.cssainc.org

Yes, Kareen, mine is the yellow flowering pear? And I was so excited when it bloomed this year! That picture of the Purple Texas Cholla(Opuntia imbricata)is absolutely beautiful! And to think it is hardy to zone 4! I will absolutely have to get one!
Thanks a bunch my dear friend.......Jean