114 Bottom Heat. 



in a pointed and philosophical manner, endeavoured to draw attention to the 

 subject. However, we want data to proceed upon ; the vegetation year, or 

 active period, is not confined by Nature to any given months, but moves by 

 periodical fits. Those fits (a clumsy term, I confess,) are dependent chiefly 

 on the relation that the bottom heat bears to that of the atmosphere. 



I am of opinion that the average bottom heat of certain periods is much 

 more in advance of the average of the atmosphere, at the same period, than is 

 commonly imagined. I know it is common to say that the average bottom 

 heat of the year is about 2 or 3 degrees in advance of the average atmospheric 

 temperature ; but this, if correct, proves nothing, except that bottom heat 

 is one of Nature's established principles. 



To obtain the data requisite, the year should be divided into natural periods : 

 one of these is obviously the rest period ; a second points itself out as the 

 excitable period ; and a third as the perfecting or accumulating period. Now, 

 it is not proper, I conceive, to plunge a thermometer 1 or 2 feet deep to as- 

 certain how vegetation is influenced by bottom heat, seeing that the chief and 

 most efficient volume of roots lies probably within from 6 in. to 9 in. of the 

 surface. The radiation, too, from the surface may also be taken into con- 

 sideration ; as the accumulation of heat by the end of August must be very 

 considerable, especially within 3 in. of the surface. 



The time was when bottom heat was only deemed essential for pines and 

 cucumbers ; but now few processes of any importance are conducted under 

 glass without it. 



Many complain that they cannot get their greenhouse and conservatory as 

 gay through the months of December, January, and February, as they could 

 wish ; and I do not wonder at it. If plants in a somewhat dormant state are 

 to be subjected to a higher temperature all of a sudden, without activity of 

 root, what can be expected but abortions ? 



I am led to make these remarks in consequence of observing the effect of 

 bottom heat in flower-forcing in general, more especially Dutch bulbs. Mine 

 have been unusually early and good ; and I adopt a practice which deserves 

 to be more generally known. My hyacinths, narcissuses, &c., are potted at the 

 usual time and in the usual way, and immediately plunged over head in old 

 tan. This so far is every body's plan ; but about the end of October I take 

 them up, and prepare a bottom heat of from 75° to 80° of dung and leaves, 

 between the bricked asparagus pits, and place the pots thereon, covering them 

 as before with old tan. When this heat declines, I prepare the next pit in 

 like wa}', and remove them into it ; keeping them, in fact, in a similar bottom 

 heat constantly. By these means I get my root in advance of the bud ; for, 

 this season, having paid close attention to their movements, I found the pots 

 were full of roots, and well coiled round the bottoms of the pots, before the 

 buds were an inch long. This I conceive to be a point of high importance ; 

 for on removing them from the asparagus pits to a forcing-pit of dung and 

 leaves, where the bottom heat was 80°, and the top heat averaging 65"^, the 

 buds came up like magic, and were in bloom in a surprisingly short period. 



The same principle applies to nearly all of what are termed forcing flowers ; 

 not excepting strawberries, which, in my opinion, would be much benefited by 

 such a process. However, I have not yet proved this with strawberries, 

 although I have several experiments in progress, bearing on the subject of 

 bottom heat, which I shall probably make known as soon as completed. 



When the various flowers possessing capabilities for forcing are taken into 

 consideration, we may fairly conclude that our conservatories and greenhouses 

 ought to be as gay in the month of January as during any part of summer, 

 and so, in fact, have mine been ; for 1 have had abundance of camellias con- 

 stantly from the first of November (some thousands of blossoms), violets, 

 lilies, azaleas, bulbs, justicias, lilacs, eranthemums, and scarlet geraniums, in 

 great profusion, now, indeed, a complete blaze of colour. 



Oidton Park, near Tar-porley, Jan. 20. 1843. 



