It´s not a secret anymore that poor gramma and bad spelling can hurt your articles ranking power. The Google team did mention it already but now we know that spelling and gramma is an important ranking factor on Bing´s search engine too. That´s what you can take from one of their articles.

Duane Forrester the Product Manager of Bing mentioned in the article “If you struggle to get past typos, why would an engine show a page of content with errors higher in the rankings when other pages of error free content exist to serve the searcher? Like it or not, we’re judged by the quality of the results we show. So we are constantly watching the quality of the content we see” and “, imagine how a reader sees this? It’s confusing when reading, to say the least. At best they simply move past the typo and keep reading. At worst they simply throw in the towel at such repeated issues and seek a new source for content to consume.”

This is a good point. I am german writer and I do write in english to improve. There is a long way to go but what I can already suggest is that most of the back ends of blogging platforms have a proofread feature. I use this here on WordPress very often and this is a good way to sort out a lot of typos. It maybe still does not help to check the gramma but it is anyway a good tool to sort out typos.