I’ve been told that the bigger the tulip bulb, the better the flower. Is this true?

Not entirely. It is true, however, that, as a general rule, the bigger the tulip bulb the bigger the flower. But bigger does not necessarily mean better. The flower bulbs of a species tulip such as tulipa tarda for example would appear quite tiny beside, say, a large darwin hybrid flower bulb such as “apeldoorn.” but these small species tulips are some of the most delicate and lovely bulb flowers you can grow. They’re quite hardy as well. Tulip bulbs are sold by calibre or size. Within any particular type or variety of tulip, the larger bulbs will fetch a higher price than the smaller ones. For big showy displays, the larger calibre bulbs are certainly worth the price. However, some excellent bargains are to be had by buying lots of smaller calibre bulbs for brightening up a marginal spot in the spring yard.