This is the world-famous culture of embroidery. Its main motive is the wonderfully blooming flower pattern and the bold variation of three bright colors on the fabric.
I also believe that the word to be use here is "motif" not motive. When you say "motif", it is a theme or a design. The main subject here is the embroidery. You are describing something about kind of embroidery which is said to be "wonderfully blooming flower......". Since you describe its kind, then you are talking about its motif and not motive.