How are bulbs measured?
A. Bulbs are usually measured in centimeters around the perimeter of the bulb. Thus, tulip bulbs that are advertised as “Size 12/14” are a minimum of 12 to 14 centimeters around the circumference of the bulbs. Some narcissus bulbs are advertised as “Topsize”. This simply means that those bulbs are among the largest available for that particular variety. Narcissus and daffodils are often advertised as “DNI”, “DNII”, or “DNIII.” “DN” means “double-nose” and refers to the fact that multiple bulbs of various sizes are attached at the basal plate. “DNI” bulbs are the largest, and up to three flowers may grow from that bulb. “DNII” bulbs are large and two flowers may grow from that bulb. “DNIII” bulbs are the smallest and least expensive. Fewest flowers will grow from DNIII bulbs. “DN” does not refer to the actual measurement around the circumference of the bulb. However the bulbs are marketed, keep in mind that the largest bulbs cost more but will produce more flowers and be most satisfying
