What is a person who grows grapevines called?
A person who grows flowers (ornimental horticulture) is called a horticulturist; horticulture is divided into a number of divisions: commercial horticulture ornimental horticulture retail horticulture public space management floriculture etc. A person who sells flowers is normally called a florist, but may have a background in design or horticulture.
The study of plants is called botany, the person who studies plants is called a botanist. Botany is a field of Life Sciences which looks at the classification and physical characteristics of plants. A person who studies the interaction of plants and animals in an environment is called an ecologist or environmentalist. A person who grows plants is called a horticulturist.