There is only one way to address this question successfully and it is with asking yourself another question:
What is your target audience when blogging?
Acknowledging the goal of your blog or company news feed, and targeting the audience that you are writing for will determine the language you blog in and shape the words and tone you will be using.
There is a goal behind any blog, from keeping a diary of your life journey, to help dozens of people on a specific topic. Whatever the goal is, the targeted audience can be from yourself, to a specific region or worldwide distribution. If this last one is the case, it is well known that english is the business language to transact all over the world, and the main language used when traveling. Wether some of your audience might not speak English, there are several tools that will help them translate your content in order to follow and understand your words.
The point here is to be well aware of your intentions and goals when blogging, and this will drive you to think of your audience and finally your blogging language.
In my case, there is another reason: mastering the language. Reading is a great way to improve any language, but writing is the best way to master it. However, this reason comes after thinking of my my target audience. I like to think that anyone could benefit of my thoughts, references and expertise on my field.
Lastly, try to think of your audience, what do they want to read, and how? This is the only way to answer What language should you blog in?
This post has been inspired by The Social Ms article with the title: Blogging in English – When It’s Not Your Primary Language that made me reconfirm why do I write in English instead of Spanish or even Catalan. Go ahead and read the post, they will convince you of using English and furthermore, they will take your fear away even though not being native in it.