18 BULLETIN 797, U. S. DEPARTMENT OF AGRICULTURE. 



class of bulbs, based upon this artificial heating, known as "Dutch 

 prepared," has been on the market for some years. These are noth- 

 ing more than bulbs whose development has been forced by artificial 

 heat while in storage. 



Very fundamental changes take place in bulbs while they lie 

 " dormant " on the shelves. Should one cut a large tulip bulb open 

 through the growing point upon digging, as soon as the leaves have 

 died down, he would probably be disappointed in not being able to 

 find readily the flower bud; but by September 15, unless low tem- 

 peratures have been maintained, the flower will have developed to 

 half the length of the bulb, and by the first of November the flower 

 may be actually protruding through the tip of the bulb. All this 

 growth has taken place in storage and is of tremendous importance 

 to the consumer, the florist, and the producer of bulbs, for future 

 behavior is largely influenced by these changes which take place 

 in the bulb house. The higher the temperature during storage the 

 more rapid is the development of the flower spike; consequently, 

 the shorter the time necessary for it to come into blossom. A long 

 period in storage produces simihir results, so that a region which 

 is able to dig its bulbs early will have bulbs that can be forced earlier 

 than where they mature later and are consequently dug late. This 

 fact is well brought out in comparative forcing tests of stocks grown 

 in the Netherlands, in Bellingham, Wash., and in Eureka, Calif. 

 Bulbs from the last-named locality are the earliest and the Holland- 

 grown bulbs the latest to flower. The time was when our early 

 forcing stocks were grown almost entirely in southern France the 

 year previous to their importation. Now earliness is brought about 

 in Holland-grown (late-dug) bulbs by a process of forcing in stor- 

 age. The indications are that, by the selection of the locality, we 

 can produce in this country the equal of the " Dutch prepared " or 

 French stocks without resorting to artificial processes. 



This all means that to the commercial grower the temperature of 

 his bulb house will be such as is natural in the region from July to 

 October, coupled with proper moisture control, and that the higher 

 the temperature the shorter the time the bulbs can be held out of 

 the ground, for after the flower begins to push out of the bulb de- 

 terioration takes place very rapidly. 



CLEANING. 



As practiced in the Netherlands cleaning is one of the tedious 

 processes of bulb culture, as it is hand labor exclusively. A great 

 deal of it, however, can be accelerated by the aid of simple ma- 

 chinery. When one has but few bulbs the operation may be done 

 by hand, but with lots of several thousand bulbs simple devices are 

 time savers. 



