You an link directly to a comment in the database. Here's how:
Go to the plant's page and click on "Reply to this comment". That will take you to a page that looks like this:
https://garden.org/thread/post...
You'll see the entire comment is quoted at the top in a box, and under that it gives you the opportunity to post a reply. But that's the page that you can link to if you want to link directly to a comment.
