There's a hint of frost in the cool night air and fall's spectacular parade of color will soon sweep down from the north. For gardeners the signs are obvious: It's time to plant bulbs again.
During the next few weeks, Northern Hemisphere gardeners will plant literally billions of spring-flowering bulbs - most of them hailing from the fields and polder lands of Holland. The Dutch, in fact, send more than 8 billion bulbs to 89 nations around the world each year.
An appropriate climate coupled with an expertise that has grown over more than four centuries has made the Dutch the world's best bulb growers. An Austrian diplomat from the royal court of Vienna brought the first tulip to Holland in 1559, little realizing the effect that simple act would have on the generally dour Dutch.
Passions for the strikingly colored flower grew to such absurd heights during the 1600s that it was not uncommon for a man to trade his home for a single bulb.
''Tulipomania,'' historians have called that period of excess, but because of it the tulip is today more a symbol of Holland than wooden shoes, windmills, or wheels of Gouda cheese.
On a pro rata basis, Americans are only moderately placed on the international list of bulb-planting gardeners, although the numbers are growing as the ease with which bulbs produce spectacular blooms is recognized. British gardeners, apparently, plant more Dutch bulbs than even Dutch gardeners. But then it should be remembered that, generally speaking, the Dutch grow bulbs. The rest of us grow the flowers that spring from those bulbs.
Each spring, the commercial flower fields of Holland bloom at their brilliant best for perhaps a day. Then the flowers are removed and scattered to the wind like so much confetti in many villages. On some farms the flowers are piled up and composted. But what seems an incredible waste is done for the ultimate satisfaction of the customer - the gardener wherever he might live.
Denied the ability to form seed because the flower has been removed, the plant devotes all its energy into producing a good bulb. That bulb contains the complete flower in embryo, along with all the food needed to grow it to perfection. The complete package, you might call it. Because of this the bulb will produce a top-flight flower even if planted in totally sterile sand. Under such circumstances the plant would not reproduce the following spring, of course.
Planted in your garden in good humusy soil and with a handful of bonemeal at the bottom of the hole, tulip and hyacinth bulbs should give you good blooms for several years. Daffodils, on the other hand, will go on producing top-quality flowers year after year, given the right treatment.
Incorporate peat moss, compost, or both to add moisture-retention qualities to light, sandy soils; clay soils are lightened by mixing in peat moss.
You can plant bulbs in individual holes dug with a bulb planter or hand trowel or, if you are into mass displays, you can excavate a large area, set the bulbs in with the pointed side up, and then spade the soil back over them.
Planting depths for North America, established by university research work, suggest 8 inches for large bulbs (tulips, hyacinths, daffodils) and 5 inches for minor bulbs (crocuses, grape hyacinths, snowdrops, aconite, etc.). Bulbs can adapt, too. Plant them a little too deep or too shallow and they will adjust.
Space the larger bulbs 6 inches apart and the smaller ones 3 inches. Planting in groups rather than in single rows is more effective. Remember, too, the more lavish your planting this fall, the more spectacular will be the display next spring.