Nope. While that might seem reasonable, it won’t work, as the subdomain is a different domain altogether, and “relative” links will only work within the same webspace.
I do not know of a way to make a “relative” link between domains, short of manipulating apache re-write rules via an .htaccess file, and that is not for the faint of heart.
Try to think of it this way: How would you make a “relative” link from one of your pages to wiki.dreamhost.com? Answer: You can’t.
Just because both domains are under “crochetgarden.com”, doesn’t mean they are not seperate “webspaces”.
Does that make any sense?