MONTHLY CALENDAR. 629» 



tutional, hereditaiy, and infectious. I believe it may also be induced by any 

 or all of the following causes : — imperfect drainage ; the use of crude and not^ 

 sufficiently decomposed manure or leaf-mould ; the presence of oxide of iron, 

 in the soil ; sudden draughts of cold air ; using water for the plants much colder 

 than the temperature in which they grow ; allowing the sun to shine on the 

 foliage, so as considerably to raise the temperature of the house previous to the- 

 admission of air in the morning ; permitting the drops of cold condensed 

 vapour to drop from the roof on the same leaf, or part of a leaf, for days, per- 

 haps weeks together ; over-watering ; using too strong manure-water ; not 

 giving water enough, or dropping the same on the leaves ; escape of gas 

 from flues ; careless fumigation and excess of moisture in the atmosphere of the 

 house, especially if it is cold and close ; and, in fine, any or everything that 

 tends to check the free current of the sap through root or branches, may pro- 

 duce, and always intensifies, the destructive energy of this disease. By care- 

 fully avoiding all these causes, the probability is, that you will never bo 

 troubled by the spot, and it is certain that your care will be rewarded by 

 healthy and beautiful plants. Green-fly is often troublesome, but it is easily 

 got rid of by fumigation, and with good culture no other insect ever attacks 

 pelargoniums. 



1975. To secure profusion of bloom, early growth and under-potting are 

 of the first importance. No matter how robustly a plant is grown, one 

 eighteen months old cannot be made to flower so freely as one four or five 

 years old. Whether the closeness of tissue, induced by age, modifies the 

 nature of the sap during its passage or not, I cannot tell. It is probable that 

 the smallness of the vessels may influence, not only the quantity, but the 

 quality of the sap. It is at least certain that age in this and many other 

 species is favourable to profuse inflorescence. Early growth is of the most 

 importance. Plants to flower in May should be cut down by the end of the 

 previous June ; have broken, been reduced, repotted, and encouraged to 

 grow two or three inches in a close cold frame, for a fortnight, and 

 have received their final stopping by the end of July, and be placed iu< 

 their blooming-pot by the 1st of November. Success depends upon their 

 chief growth being completed before Christmas. No after-management can 

 compensate for the neglect of early growth. Any size of plant or leaf may 

 be obtained at any period ; but the flower will be scarce unless early growth 

 is secured. Under-potting is the next great point. Plants in general, and 

 pelargoniums in particular, flower best when they are pot-bound ; that is, 

 when the roots are trying with all their strength to burst the pot asunder. 

 The energy they thus acquire appears to rush to the other extremity, and 

 expend itself in flowers. Some varieties will scarcely flower at all unless 

 their roots are in this condition. The reason seems to be, that whatever tends 

 to check the extension of other parts, favours the development of flowers. The 

 vital energies arrested in the formation of wood, concentrate their force in the 

 exhibition of bloom. It would appear as if the vital force in plants was not 

 sufficiently powerful to carry on both these functions simultaneously. At aU 



