"The Gardener" by S.A. Bodeen

Mason visits his mom at the nursing home where she works. While he's there, he notices some teenagers are "living" there, which is weird, given nursing homes are normally for old people. The teens are comatose, except for one gorgeous girl who wakes up. She's able to talk to Mason, and he quickly realizes that these special patients may be in trouble. Before he can realize what's happening, Mason is helping the girl escape.

It turns out the hospital is not your typical place for medicine and health. In a special greenhouse, a man called the Gardener is conducting unique experiments. Scientists who work for the Gardener are concerned that the planet will soon run out of food, due to overpopulation and climate change. They are working to develop human autotrophs - humans that don't need to eat, but who can produce and consume their own energy, just like plants!

But, something about this project doesn't seem right, and hospital authorities are soon chasing after Mason and the mysterious girl from the hospital. Is she connected to the Gardener? Something about her isn't quite right, but Mason is determined to protect her at all costs.