ArdourVST not vst_ path ?

I have installed ardourVST 2.8.4.
But echo $VST_PATH gives no result.

I just edit .bashrc
export VST_PATH=/home/anton/vst/

Then restarted now it works.

Otherwise I think you just could have created the directory /usr/lib/vst which is where fst would look for it. I have done it a little different than you. I have a link from /home/myname/vst to /usr/lib/vst as I also use Rosegarden with vst as well as vst apps as standalone synths. This way I use the deafault location for both the fst and dssi-vst libs as well as having write-permission to the directory.