BOOK I. PINERY. GENERAL CULTURE. 533 



after renewal, there will be four or five weeks to run, while the heat is to be sustained on the old mate- 

 rials, which will be generally found a convenient distribution of this business. In the continued hot 

 weather of tull summer, the fermentation in the bed may decline faster than the strength of the tan is 

 given out, from the mass of tan getting excessively dry. In this case, pour as much water on the surface 

 between the pots, as, in addition to that passing through the pots in common waterings, will restore suffi- 

 cient moisture to the bed. With a small fork, keep the surface of the bark free from fungi or crustv 

 spawn, which are apt to generate there. 



2857. Substitutes for tan. Tan is in many places scarce and dear, and in others not to 

 be got; in either case it becomes an object to know the best substitutes, and their manage- 

 ment. Horse-dung alone, as already observed, is used by some-; and, by others, mixed 

 with bark, with ashes, with leaves, sawdust, shavings, clippings of leather, chopped 

 spray, and such other durable substances as can be brought to ferment along with it, and 

 prolong its duration as a fermenting mass, 



2858. Nicol, when tanners' bark is difficult to be procured, recommends a mixture of leaves with stable 

 litter, using only a little bark (fifteen or eighteen inches), in which to plunge the pots. But in using leaves" 

 or leaves mixed with litter, they must always be well fermented, and the rank heat extracted out of them 

 before they are made up into a bed for the plants. 



2859. Ncifl observes, that flax-dressers' refuse ferments very slowly and regularly, and that used instead 

 of stable-dung, it will keep up a steady heat longer than almost any other substance. 



28GO. Oak-leaves. Speech! y used oak-leaves with great success, and gives the follow- 

 ing directions for their preparation : 



2861. After being raked into heaps, they should immediately be carried to some place near the hot-house 

 where they must lie to couch. I generally fence them round with charcoal-hurdles, or any thing else to 

 keep them from being blown about the garden in windy weather. In this place we tread them well and 

 water them in case they happen to have been brought in dry. We make the heap six or seven fe'et in 

 thickness, covering it over with old mats, or any thing else, to prevent the upper leaves from being blown 

 away. In a few days the heap will come to a strong heat. For the first year or two that I used these 

 leaves, I did not continue them in the heap longer than ten days or a fortnight ; but in this I discovered a 

 considerable inconvenience, as they settled so much when got into the hot-house, as soon to require a 

 supply. Taught by experience, I now let them- remain in the heap for five or six weeks, by which time 

 they are properly prepared for the hot-house. In getting them into the pine-pits, if they appear dry, we 

 water them again, treading them in layers exceedingly well, till the pits are quite full. We then cover 

 the whole with tan to the thickness of two inches, and tread it well, till the surface become smooth and 

 even. On this we place the pine-pots in the manner they are to stand, beginning with the middle row 

 first, and filling up the spaces between the pots with tan. In like manner we proceed to the next row, till 

 the whole is finished ; and this operation is performed in the same manner as when tan only is used. 



2862. Thus prepared, they will retain a constant and regular heat for twelve months without either 

 stirring or turning; and if I may form a judgment from their appearance when taken out, (being 

 always entire and perfect,) it is probable they would continue their heat through a second year; but, 

 as an annual supply of leaves here is easily obtained, such a trial with us is hardly worth the trouble 

 of making. However, as a saving in leaves may be an agreeable object in places where they are less 

 plentiful, I was induced to make the following experiments : In 1777, one of the pine-pits was filled 

 with one part of old, and two parts new leaves well mixed together ; and the next year, 1778, one 

 pit was filled with old and new leaves in equal quantities : in both these experiments, I had the 

 satisfaction to find the pits so filled to retain a heat through each season, equal to the other pits that 

 were filled entirely with new leaves ; and since that time we have always used the whole of the 

 undecaycd leaves mixed along with the new ones. I also have constantly used the leaves after 

 they were taken out of the hot-house in the early-made hot-beds, and always found them to answer 

 quite as well as fresh leaves. I must beg leave to observe, that when the leaves are intended to be used 

 a second time, it will be proper at the taking them out of the pits to remove some few at the top, as also 

 on each side ; because the leaves at the top and outside of the pit approach most to a state of decay. 

 After this the pines will have no occasion to be moved but at the stated times of their management; viz. 

 at the shifting them in their pots, &c. when at each time, a little fresh tan should be added to make up 

 the deficiency arising from the settling of the beds ; but this will be inconsiderable, as the leaves do not 

 settle much after their long couching. During the two first years of my practice, I did not use any tan, 

 but plunged the pine-pots in the leaves, and just covered the surface of the beds when finished, with a 

 little sawdust, to give it a neatness. This method was attended with one inconvenience ; for, by the 

 caking of the leaves, they shrunk from the sides of the pots, whereby they became exposed to the air, and 

 at the same time the heat of the beds was permitted to escape. Many powerful reasons may be given 

 why oak-leaves are preferable to tanners' bark. I believe that oak-leaves are preferable to those of any 

 other sort ; but I have found, by repeated trials, that the leaves of beech, Spanish chestnut, and horn- 

 beam, will answer the purpose very well. It seems, that all leaves of a hard and firm texture are very 

 proper ; but soft leaves that soon decay, such as lime, sycamore, ash, and of fruit-trees in general, are 

 very unfit for this mode of practice. 



2863. Superiority of oak-leaves. They always heat regularly; for, during the whole time that I 

 have used them, which is near twenty-five years, I never once knew of their heating with violence ; and 

 this is so frequently the case with tan, that I affirm, and indeed it is well known to- every person convers- 

 ant in the management of the hot-house, that pines suffer more from this one circumstance than from all 

 other accidents put together, insects excepted. When this accident happens near the time of their fruit- 

 ing, the effect is soon seen in the fruit, which always comes ill-shaped and exceedingly small. Sometimes 

 there will be little or no fruit at all ; therefore, gardeners who make use of tan only for their pines, should 

 be most particularly careful to avoid an over-heat at that critical season the time of showing fruit. 



2864. The heat of oak-leaves is constant ; whereas tanners' bark generally turns cold in a very short 

 time after its furious heat is gone off. This obliges the gardener to give the tan frequent turnings, in 

 order to promote its heating. These frequent turnings, not to mention the expense, are attended with 

 the worst consequences ; for, by the continual moving of the pots backwards and forwards, the pines are 

 exposed to the extremes of heat and cold, whereby their growth is considerably retarded ; whereas, when 

 leaves are used, the pines will have no occasion to be moved but at the times of potting, &c. The pines 

 have one particular advantage in this undisturbed situation ; their roots grow through the bottoms of 

 the pots and mat amongst the leaves in a surprising manner. From the vigor of the plants, when in this 

 situation, it is highly probable that the leaves, even in this state, afford them an uncommon and 

 agreeable nourishment. 



2865. There is a saving in point of expense, which is no inconsiderable object in places where tan 

 cannot be had but from a great distance, as is the case here, the article of carriage amounting to ten shil- 

 lings for each waggon-load. Indeed, this was the principal reason that first induced me to make trial of 

 leaves. 



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