What is a mass of flowers called?

A mass of flowers could be called a bouquet.

Certain types of flowers are referred to as mass flowers. Examples are: rose, carnation, gerbera, sunflower, lily, daffodil, tulip, iris, freesia, zinnia, alstroemeria, protea and chrysanthemum. They are usually the main flowers in a bouquet.

Mass planting is filling in an area in the landscape with flowers of one or more types.