i still remember having the begeezus scared out of me as a tyke when I first watched the “day of the triffids”, but not too many years later i laughed at “salt water” being the big solution to killing them. Now, using “salt water” as a killing solution is a meme equivalent to witches melting in the rain.
https://en.wikipedia.org/wiki/The_Day_of_the_Triffids_%28film%29
I've actually never seen that one, remember when it was out, that's about it. Sci-fi is part of the horror genre (aliens instead of monsters, technology or maybe telepathic or empathic 'powers' instead of magic, etc), and while I sometimes enjoy science fiction, horror is just dopey. :^) Reading your post, I do wonder if the salt water thing was an homage (or send-up) when it was used in the movie "Alien Nation".