Giant-flowered usually over 254 mm. (10 inches) in diameter.
Large-flowered usually between 203 mm. (8 inches) and 254
mm. (10 inches) in diameter.
Medium-flowered usually between 152 mm. (6 inches) and
203 mm. (8 inches) in diameter.
Small-flowered usually between 102 mm. (4 inches) and 152
(6 inches) in diameter.
Miniature-flowered not usually exceeding 102 mm. (4 inches)
in diameter.
Small Ball dahlias usually between 102 mm. (4 inches)
and 152 mm. (6 inches) in diameter.
Miniature Ball dahlias usually between 52 mm. (2 inches)
and 102 mm. (4 inches) in diameter.
Pompon dahlias not exceeding 52 mm. (2 inches) in diameter.