Ellen (Katherine Houghton; Guess Who's Coming To Dinner) and her husband John (James Congdon) enjoy the good life in their lovely Costa Rica home - all that's missing is a nice garden. Enter the mysterious and dangerously handsome Carl (Andy Warhol superstar Joe Dallesandro), who creates a botanical paradise while casting a spell on Ellen and her woman friends. Things take a turn for the worse when Ellen discovers that her Gardener may be planting his own "seeds of evil".
Notorious for its casting of real circus freaks, this is the story of Professor Nolter (Donald Pleasance), who is trying to solve the world's food crisis by genetically engineering a new breed of plant by crossing human DNA with plants. His human victims are supplied by the horribly deformed Lynch (Tom Baker) who works for a local circus freak show and whom the loony professor promised to rebuild. However, things go horribly array when the circus freaks figure out what the professor is really up to - engineering a new hybrid man-plant freak of Nature.