General (Bulbs 101)
Keukenhof is to bulb lovers what Cooperstown is to baseball fanatics. 7.5 million bulbs bloom across 70 acres during the six weeks that this amazing show garden is open. There are more than 1.7 million tulips alone! This dazzling display attracts tourists from around the world and is a sensational backdrop for countless weddings.
Three reasons: the climate, the coast and Carolus Clusius, who introduced tulips to Holland in the 16th century. At the time, the Netherlands was a leading center of trade. As tulip fascination caught on, the Dutch began cultivating them more professionally. Add to this a marine climate (mild winters, cool summers) and a particularly well-suited strip of land just inside the Dutch dunes (proper soil with good drainage, consistent water levels) and the global bulb trade was born. Today, expanses of land in the northern regions of the Netherlands are where the action happens and where the millions of the bulbs we know and love today have their ancestral home.
I have seen the same variety of bulb priced very differently, some very cheap and others quite expensive. What's the difference?
In a word: size. Bulbs from Holland are gauged by "caliber" which is the circumference of the bulb. Since larger bulbs yield larger flowers, they typically cost more. Smaller caliber bulbs are younger and often cost less. For plantings in a front bed or other highly-visible garden setting, it's worth the higher price for the grander display. If you have a larger area or a portion of yard that's less visible, smaller caliber bulbs can add color and enliven the scene at lower cost. Left in the ground, these bulbs will naturalize and eventually become bigger bulbs. By the way: the Dutch will not export bulbs below certain established calibers. Tulips, for instance, must be 4 inches (10 cm) or larger without exception. Only naturally sized species tulips fall outside this guideline, but no other tulip bulb smaller than 4 inches (10 cm) will be exported from Holland.
Bigger doesn't necessarily mean better. Bigger bulbs do yield bigger flowers, but tulipa tarda — among the most delicate and lovely bulb flowers you can grow — is a tiny bulb (and quite hardy) compared to a large Darwin hybrid bulb such as 'Apeldoorn.'