Blog comments are a vital part of all blogs, because they make blogs social. Without comments, a blog is just like any other one-sided conversation on a website that reports and talks at its audience rather than with its audience. For your blog to grow and thrive, you should not only allow comments on all of your blog posts, but you shouldn't close them either.
Keeping blog comments open indefinitely is particularly important because blog archives live forever. You never know when someone might stumble on one of your blog posts through a search engine or link on another website and want to comment on that post. If your posts are timeless, there is no reason to stop the conversation by closing comments at a specific point in time.
However, there are exceptions to every rule, and closing blog comments is not immune to its own exceptions. With that in mind, following are some reasons why you might consider closing comments on individual blog posts.
To Reduce Spam Comments
Older blog posts attract a lot of blog comments that are spam. It can be time consuming to moderate all of those spam comments, so if a specific older blog post is generating a lot of spam comments, you can close comments on that single post to eliminate the problem.
To Manage Time Sensitive Posts
Sometimes you'll publish a blog post that is highly time sensitive. For example, you might publish a post announcing a blog contest and inviting people to enter the contest. If you continue to get comments and entries through that blog post long after the contest is over, you might want to turn comments off on that post. This eliminates the need for you to continually respond to those comments to let people know the contest is over. Closing comments on these types of posts can also improve the user experience on your blog.
To End a Controversial Conversation
It's very possible that you could publish a post that's not at all controversial but it becomes controversial through the comments people submit to it. For example, a blog post could launch a volatile political debate or an argument about any number of topics. Sometimes these debates take an ugly turn and your blog post becomes a place for nasty arguments, hate-filled comments, and personal attacks. In order to put a stop to the problem, you can close comments on that post. Just be sure to include a note in the post body to explain why comments had to be turned off. Also, be sure to refer to your blog comment policy within your update, so people know what types of comments are acceptable on your blog in the future. See a sample blog comment policy.
Remember, your blog is your space online. You control it and you can configure it in anyway you want to meet your individual goals. If you want to close blog comments, then that's your prerogative.
Most blogging applications give you the option to close posts on all posts (so no one can comment on any of your blog posts) or on posts that are a specific number of days old. For example, if you want to close comments on all posts once they reach 90 days old, you can do so in your comment settings. Another option is to close comments only on specific posts, as most of the examples above would require. Don't worry. You can always turn comments back on at a later date if you want to.