2014 subaru outback 3.6 r

Perhaps you need a block heater. If the battery is weak you should replace it with a high capacity battery like Optima.

Thank you Mark. The Dealer changed the battery yesterday, but it did the same thing this morning. I fell like I should pull out the choke.... If they can't work it out next week (when it will be cold again ) I'll try the block heater. Thanks again Julian

Does it turn over slowly when cold but normally when warm? I hate to tell you this but dealers install the inadequate stock battery instead of good ones.

No, the engine turns over normally with the new battery or with the old it is as though it is not getting any petrol

I would try using a good fuel system cleaner such as Techron. It is possible your fuel pump is getting tired. I re read your initial post. 0 degrees C is not really cold at all which means there is a problem that a block heater won't fix.