Transactions of the Prussian Gardening Society. 435 



watering the roots and the tops, should be from 67° to 68° 

 Fahrenheit. Plenty of air should be given in the daytime, 

 unless the weather is unusually severe : the want of abun- 

 dance of fresh air at this season is one chief cause of the fly 

 {blattlaus). 



c 2. From the Appearance of the Blossom to its fill Expansion. — 

 In the open air, the cherry blossoms in the last half of April, 

 and in the first week of May ; therefore, agreeably to our prin- 

 ciple of imitating nature, this will give the temperature to be 

 maintained in the cherry house, during the last half of January 

 and the first week of February. It may, however, be raised a 

 little higher when the blossoms are completely expanded, or 

 from 6* J to 68° Fahr., but must afterwards be lowered to. 

 56° or 51°. It has been observed that, when cherries have 

 been in blossom in the open air in April, snow has fallen, and 

 that the crop of cherries has, nevertheless, been very abun- 

 dant. From this and various observations it appears that, 

 though a temperature of from 64° to 74° Fahr. may be favour- 

 able for the full expansion of the blossom, and the develop- 

 ment of the pollen, a far less temperature is sufficient, and 

 even favourable, for strengthening the incipient fruit. The 

 trees cannot be sprinkled while in blossom, but an equally 

 advantageous effect may be produced by watering the flues. 

 To promote the setting of the fruit, shake the trees by hand, 

 in imitation of the natural winds of April ; and shade from the 

 intense rays of the mid-day sun, by gauze covers, in imitation 

 of the passing clouds of that season. These gauze covers also 

 prevent the accumulation of too great heat in the house, and 

 check the production of the mildew and the fly {blattlaus). No- 

 thing promotes the production of the blattlaus more than the 

 sudden admission of cold fresh air, when the house is raised to 

 a high temperature. The blattlaus is to be kept under by 

 filling the house with the smoke of tobacco. " The gardener 

 must not think it too much trouble to put on and take off the 

 gauze covers, often several times a day, during the blossoming 

 season." 



3. From the Blossoming to the Stoning of the Fruit. — The 

 setting and stoning of fruit in plants may be compared to the 

 breeding of teeth in young children, being for both a critical 

 period. The time required, from the commencement of the 

 opening to the full expansion of the blossom, is between six 

 and eight days in the open air, but a longer period is neces- 

 sary in the forcing-house. About the same length of time, 

 and the same variation between the open air and the forcing- 

 s' f 2 



