Does the cold weather kill everything or...

Hi. This year I was the proud owner of 4oz. that I grew myself. It was my first time growing so I think I did very well to get that much off of one plant. But anyway, since I only had 1 plant, I didnt want to take any chances with it so I harvested like 2 weeks ago. The temp. outside was getting below 30 degrees at night. I was worried about the weather killing it. Then after I harvested, a fellow grower I know, said that the weather will kill everything on the plant EXCEPT the buds. I'm not too sure about that so I figured I'd ask you guys. Thanks.