This one acre, family owned botanical garden and cactarium in Palm Springs is filled with 3000 varieties of desert plants. I would love to visit on my next trip to the States.
Photos one, two, six and seven by Amy Merrick. Three, four and five by Chuck B.
More info on the garden here.
The Secret Garden 
Great pictures. Looks like some strange forgotten world where cacti run riot. Could not be more different from an English Garden. What a joy to see!