Hydroponics outside in the winter?

I am starting some hydroponic experiments in my house.  I started wondering, can hydroponics be used outside?  It does get down to 0C where I like, not usually more than 8 times a year but it is very damp.  What is the lowest temperature for the plant substrate - root system?

I once visited a hydroponics farm in the north that specialized in growing basil, it was a all set up in greenhouses and produced organic crop all year long supplying local grocery store chain.

I get no active growth in the cold, but I've had perennials overwinter in my system. Mostly clover and weeds, but also including strawberries and apples. My fish are all hardy against my winters. Goldfish and minnows at that time. Goldfish, koi and crayfish now. My tank has always frozen on top, but they survive underneath. It's never stayed cold long enough to freeze solid, I don't think they'd survive that.