Sounds like what we call a "7-B" climate zone... Let's see, -4C is around 20 Degrees Fahrenheit, if I am not mistaken...

Hmmmmmm??? Yeah, sounds like a perfect place to garden even with the dry climate...

I still kind wonder what it is you expect to achieve, Sister-C... Ornamentals??? Food??? Flowering plants??? Shade??? No shade??? Privacy???

B~