Flowers in the Attic' has had a few adaptations, and whether you can watch them for free really depends on where you look. I recently stumbled upon the 2014 Lifetime version while browsing Tubi—it was totally free with ads, which wasn’t a big deal since the breaks were short. Sometimes platforms like Crackle or Pluto TV rotate older movies like this, so it’s worth checking there too. I’d avoid shady sites, though; the pop-up ads are nightmare fuel, and the quality’s usually garbage.
If you’re into the gothic vibe of the book, the movie captures the creepiness pretty well, though it cuts some of the darker details. Heather Graham’s performance as the mom is chilling in the best way. For a free legal option, I’d bookmark JustWatch to track where it’s streaming—it’s saved me so much time hunting down films.