Hornwart is more like a weed, it grows fast, minimal lighting, floating (no roots req'd) and you can add weights to hold it down if you like.
In my small tanks, I just let if float, and prune it every so often.
If I had a preference, I would only have 1 male per 3 gal tanks. The only reason I used dividers now is because I had to seperate my females (they were all in the 3gal) because Reena would pick on the other two constantly.
Once I can dig-up, steal (indefinately borrow I mean) or afford a bunch of new tanks, I will have one 3gal tank per male, and a divided tank for my females.