No Blade of Grass...I saw that movie 39 years ago! What a date! Garnett Theater, Tulsa, OK. Now closed.
The book was ...interesting. I have been a fan of post-apocalytic fiction for years.
Alas Babylon
Lucifer's Hammer
Some of the recent Jonny Ringo books in the Looking Glass series
Some writers do have a very. .. let's say 'vivid' imagination.