532 PRACTICE OF GARDENING. PART III. 



warmth In the house to cause young roots to spring from the stems of the plants to draw 

 into them sufficient nourishment to sustain them ; and farther, if the roots of fruiting plants 

 be destroyed in winter, it will probably hinder them from showing fruit in time to ripen, 

 or make them show weak." (Gard. Rem.) 



2848. Abercrombie and Nicol agree in the following standard for the different classes of pines, allowing a 

 latitude of from five to eight degrees, below or above : Nursing bark-bed 75 ; Succession bark-bed 72 ; 

 Fruiting bark-bed 82. The standard for the succession-pit is fixed lower than that for the nursing-pit, to 

 guard against the chance of starting the plants into untimely fruit. Abercrombie observes, that when the 

 bottom heat of a bark-pit is as high as 80, with a layer composed of old and new tan at top, that layer will 

 scarcely exceed 65. " Many persons," he adds, " work pine-stoves with a bottom heat five or ten degrees 

 higher than the maximum standard set down for each house above. These, on the one hand, and the 

 theorists, on the other, who censure the application of any bottom heat to exotics as unnatural, both seem 

 to be in extremes. In tropical climates, the earth itself about the roots of plants is frequently so pene- 

 trated with the violent heat of the atmosphere, as to maintain a temperature of 80 degrees, or more, in the 

 shade ; consequently, for the roots of exotics from such climates to be plunged into a bed heated to that 

 degree is not unnatural : still it should be recollected, that the heat of the air there has a proportionate 

 elevation above that of the earth. During our winter, therefore, instead of keeping the roots of 

 pine-plants in a factitious heat of 80, while the artificial temperature of the air is, in some cases, let 

 down to 55 and 60, perhaps a better relation of the bed with the atmosphere would be supported by 

 having the bark-bed at 60*? or 65, and the air of the pit at 70, at least never less than the heat at the 

 roots." 



2849. The measurement of bottom heat is effected by keeping trial-sticks in the bed, 

 which M'Phail considers sufficient for any experienced person ; but the most accurate 

 mode is, to plunge the bulb of the thermometer about a foot into the bed, till it reach that 

 depth where the layer of old bark into which the pots are plunged, and the fermenting 

 mass may be supposed to join. This will give the heat at the bottom of the pots. 



2850. Renewal of the bark-bed. When the decline of the bed below a given temper- 

 ature requires it to be renewed, take out the pots, tie the leaves carefully with bass, to 

 protect them from being broken, and set them in a place where the plants will receive no 

 check. If the top layer be earthy and decayed, so as to run through the screen, take it 

 entirely off. Let the rest of the old bark be screened, and that which passes through be 

 carried out of the house. Bring in new bark equal to the quantity taken away ; but, be- 

 fore mixing it with the retained portion of the old, separate the least efficient of the old to 

 serve as a top layer. Proceed then to mix the new bark equally with the soundest part 

 of the old, turning over the bed from the bottom with a fork. Tread this part equally. 

 To receive the pots, spread on lightly at top a layer composed three fourths.of old bark, 

 extending at least to the depth of the pots. Dress the surface of the bed full up to the 

 sides of the pit, making it rather higher in the middle. After renewing a bark-bed, if 

 there has been a great proportion of new tan introduced, or if there is any probability that 

 the heat may rise excessively, plunge the pots but one third of their depth into the bark, 

 or set them merely on the surface, till the full heat has risen and been found not in ex- 

 cess ; then plunge them to the rims. 



2851. Reviving tan with the fork. If it be not requisite to take off the top, begin at one 

 end of the bed, and dig out as much bark as will allow the remainder to be loosened, and 

 completely forked over, without spilling any into the house. Fork it accordingly ; return 

 the bark taken out, level the top, and replunge the pots to their rims. 



2852. Times of renewing and reviving the bark-bed. After the bark-bed has been re- 

 newed by the substitution of new bark for that which is quite wasted, it may be expected 

 to last in good action, with the help of an intermediate forking up, for ten or eleven weeks ; 

 consequently, it will require renewal about five times in the year. As a gradual decline 

 must take place between one renewal and another, the heat can scarcely be kept by any 

 management from fluctuating less than ten degrees ; and therefore, in planning the busi- 

 ness of the year, it is a desirable thing to distribute the times of renewal so that they may 

 just precede those periods when something critical depends on having the bajk-bed at a 

 maximum heat. The principal occasions seem to be these : 



2853. The time of the principal annual potting and repotting, when established plants are advanced to the 

 last and intermediate stages, and new plants are brought into the nursing-pit. This will commonly fall in 

 the first week in August ; but let it fall when it will, one of the fundamental reparations of the bed must 

 be adapted to it ; because the plants want a good growing heat to strike them, and the successive clearance 

 of one pit after another affords the easiest opportunity for shifting the bark. 



2854. That crisis of autumn when the weather is declining, yet not cold enough to light fires. This hap- 

 pens about the beginning of October, and may commonly follow too close after the entire restitution of the 

 bed to admit of timing the second renewal exactly to it ; the bed may be, however, well forked up, when 

 the season is on the turn. The second renewal will scarcely be demanded by the state of the bed till eleven 

 weeks after the first. As it respects the fruiting-house, it should be particularly sound and complete, to 

 allow of timing the third to a critical period in the culture of the pine. Rather protract the interval be- 

 tween the second and third renewal to three months or more, than precipitate the third, which might start 

 the plants too soon into blossom. In the fruiting-house, accordingly as you calculate that the plants 

 will show fruit at the end of January or later, renew the bed just before, in the proportion of one third, 

 if necessary, so as to have the bed steadily up to 80 when the plants come into flower. 



2855. In March. A shifting of the roots into larger pots is frequently requisite for plants in the nursery 

 and succession pits about the middle or end of March. Whenever repotted plants are to be struck, the 

 bed should be prepared for yielding the approved degree of heat. 



2856. In May. The same principle prescribes a renewal at the partial repotting, which is commonly made 

 at the end of May. This may be combined with another object: contrive to have the pit in lively action 

 just before you discontinue fire-heat As to forking up merely : if this be done at the end of six weeks 



