Stay out of the basement - R. L. Stine

They're baa-ack! Make way for the bestselling children's series of
all time! With a fresh new look, GOOSEBUMPS is set to scare a whole
new generation of kids. So reader beware--you're in for a scare!
Dr. Brewer is doing a little plant-testing in his basement. Nothing
to worry about. Harmless, really. But Margaret and Casey Brewer
are worried about their father. Especially when they...meet...some
of the plants he is growing down there.
Then they notice that their father is developing plantlike tendencies.
In fact, he is becoming distinctly weedy-and seedy.
Is it just part of their father's "harmless" experiment? Or has the
basement turned into a garden of horrors?