Each year, i get very frequent bloody noses during the winter (2x a week). what can i do to stop them? vitamin k supplements? saline spray?

Dry nose?: If this only happens during the winter, most likely the lining of your nose is getting too dry and cracking, causing nose bleeds. Using saline spray is reasonable as well as using a humidifier. Also a little bit of vaseline can be helpful for some. Since this is most likely not a problem with coagulation, vit k won't help. If continues and is really bothersome, visit to ENT doc may be warranted.

Epistaxis: Nosebleeds are common, especially during the winter time. Using heat can dry out the nasal cavity. Also, if there is a septal deviation (also very common), there might be thinned mucosa on one side making it more susceptible. Keep the nose moist with a saline sinus rinse bottle and consider ayr gel if there is one particular dry/bleeding spot. See an ENT if you want it looked at!