multiple blogs or just one?

Which is better for SEO?

[numnum]

I operate a site with three related but distinct topics, each with it own discrete audience. I don't want to break it up into three separate sites because I'll lose too much link juice.

I'm developing a blog to improve traffic. From an SEO viewpoint, would it be better to use one blog -- perhaps as the site's home page -- or three separate blogs, each as the main page for the three distinct site areas (topics)? The problem with one blog is that most posts would not be relevant to any given visitor. And no, I will not be using category labels or tags to parse the posts for visitors. That option is out. Don't even ask me why. It just is.

I guess what I'm wondering is if Google blogsearch or general search views more favorably a single blog with, say, three-times-per-week posts than three separate blogs, each with once-per-week posts -- all else being equal.

[adder]

And no, I will not be using category labels or tags to parse the posts for visitors. That option is out. Don't even ask me why. It just is.

oh, ok... that was exactly what I was going to suggest especially as there are so many great plugins that make managing categories and tags a breeze both for visitors and search engines but I won't ask :)

Having 3 separate blog installations is going to be a webmastering nightmare. Imagine customising, updating and tweaking a blog and then repeating it all on two other blogs.

I think the answers is in how related those topics are. If a visitor was interested in topic A but he ended up landing on topic B. Would he bounce or would he still read the article on topic B? Then, considering you're going to ditch categories and tags (which means you will struggle to serve meaningful "related posts" to a visitor) will the visitor be able to navigate to topic A - which is what he's mainly interested in?

As far as search engines are concerned, there's very little difference between having
example.com/blog1/topic1.html
example.com/blog2/topic2.html
example.com/blog3/topic3.html

or having

example.com/blog/topic1.html
example.com/blog/topic2.html
example.com/blog/topic3.html

(unless you mess something up with the installation, permalinks etc etc)
So, for me, the best advice would be - think about the visitors and forget the search engines.

[numnum]

As far as search engines are concerned, there's very little difference between having
example.com/blog1/topic1.html
example.com/blog2/topic2.html
example.com/blog3/topic3.html

or having

example.com/blog/topic1.html
example.com/blog/topic2.html
example.com/blog/topic3.html

Right, that is the issue -- whether there's an SEO advantage per se in using one vs three blogs. My hunch is that the answer is no. So which to use depends on which users will find more useful.

In my case, I think three distinct blogs is better, mainly because the three topics are mutually exclusive (even though they are related). It would make little sense to require any user to scroll past two irrelevant posts or check an RSS feed twice unnecessarily to get to a third, relevant one.

Also, contextual ads would probably be more relevant in the case of three separate blogs, at least in theory. Right?

Finally, the names of the blogs themselves would be more specific and hence more likely to attract the right audience. Fewer bounces off the site.

[incrediBILL]

Building a site for 'link juice' is silly, build it for the 3 distinctly different audiences and if it's quality it will rank as 3 stand alone sites. For instance, If you had a site catering food and selling shoes it would be a big old mess all mixed together. I wouldn't mix them unless they're related, but that's just me.

If you split them up your 301 redirects to the new sites would pass the PR along.

I have a bunch of sites and getting a PR3/4 isn't hard, 5+ takes a little more work.

Imagine customising, updating and tweaking a blog and then repeating it all on two other blogs.

If they use the same layout you would only update one common staging copy and then deploy it on all 3 blogs, not hard at all.

If they are going to have 3 totally different topics, I'd host them on 3 different blogs.

[Dether]

If these are the three related somehow thematically categories, I'd left it on one blog. Separate it clearly into categories, so that users who are interested in only one subject could easily find articles about it. Add rss channels to specific categories so that users can track entire blog as well as specific categories. I would do it in that way if I were you.