The blog is not going away. So if it's a blog post you are referring to, it will still be there!
I totally know what you mean! I have a few nieces that like to post anything and everything - sometimes 10-15 posts a day!
What I've done is to click on their name, and then there's some grey buttons: Friends, Following, Message, ... Click on Following and change it to "Unfollow". You are still friends, but their posts won't be in your newsfeed. I know that might not work for you; I thought I'd throw it out there anyway.