Gardeners Dictionary: Tan
containing The Best and Newest Methods of Cultivating and Improving The Kitchen, Fruit, Flower Garden, and Nursery; As also for Performing the Practical Parts of Agriculture: Including The Management of Vineyards, With the Methods of Making and Preserving Wine, According to the present Practice of The most skilful Vignerons in the several Wine Countries in Europe.
Together with Directions for propagating and improving, From real Practice and Experience, All sorts of Timber Trees.
The Eight Edition,
Revised and Altered according to the latest System of Botany; and Embellished with several Copper-Plates, which were not in some former Editions.
By Philip Miller, F. R. S.
Gardener tothe Worshipdul Company of Apothecaries, at their Botanic Garden in Chelsea, and Member of the Botanic Academy at Florence.
Printed for the Author;
M. DCC. LXVIII.
Tan, or Tanners Bark is the Bark of the Oak-tree, chopped or ground into coarse powder, to be used in tanning or dreffing of skins, after which it is of great use in gardening: first, by its fermentation (when laid in a proper quantity,) the hear of which is always moderate, and of a long duration, which renders it of great service for hot beds; and secondly, after it is well rotted, it becomes excellent manure for all sorts of cold stiff land, upon which one load of Tan is better than two of rotten dung, and will continue longer in the ground.
The use of Tan for hot-beds has not been many years known in England. The first hot-beds of this sort, which were made in England, were at Blackheath in Kent, above fourscore years ago; these were designed for the raising of Orange-trees, but the use of these hot-beds being but little known at that time, they were made but by two or three persons, who had learned the use of them in Holland and Flanders, where the gardeners seldom make any other hot-beds; but in England there were very few hot-beds made of Tanners Bark before the Ananas plants were introduced into this country, which was in 1719, since which time the use of these hot-beds has been more general, and are now made in all those gardens where the Ananas plants are cultivated, or where there are collections of tender exotic plants preserved; and the gardeners here are now better skilled in the making and managing of these hot-beds than in most other countries, which might render it less necessary to give a full description of them here; but yet, as there may be some persons in the remote parts of England, who have not had an opportunity of informing themselves of the use of Tanners Bark for this purpose, I shall insert the shortest and plainest method of making and managing these hot-beds, as they are practised by the most knowing persons, who have long made use of these hot-beds; and first, I shall begin with the choice of the Tan.
The tanners in some parts of England do not grind the Bark to reduce it into small pieces, as is commonly practised by the tanners near London, where there is great difference in the size of the bark, some being ground much smaller than the other, according to the different purposes for which it is intended; but in many places the Bark is only chopped into large pieces, which renders it very different for the use of hot-beds; for if the Tan is very coarse, it will require a longer time to ferment than the small Tan; but when it begins to heat, t will acquire a much greater degree, and will retain the heat a much longer time than the small; therefore where there is choice, the middling-sized Tan should be preferred, for it is very difficult to manage a hot-bed when made of the largest Tan; the heat of which is often so great, as to scald the roots of plants, if the pots are fully plunged into the bed; and I have known this violent heat continue upward of two months, so that it has been unsafe to plunge the pots more than half their depth into the Tan, till near three months after the beds have been made; therefore where the persons, who have the care of these beds, do not diligently observe their working, they may in a short time destroy the plants which are placed in the beds: on the other hand, if the Tan is very small, it will not retain the heat above a month or six weeks, and will be rotten and unfit for a hot-bed in a short time; so that where the middle-sized Tan can be procured, it should always be preferred to any other.
The Tan should be always such as been newly taken out of the pits, for if it lies long in the tanners yard before it is used, the beds seldom acquire a proper degree of heat, nor do they continue their heat long; so that when it has been more than a fortnight or three weeks out of the pit it is not so good for use as that which is new. If the Tan is very wet, it will be proper to spread it abroad for two or three days, to drain out the moisture, especially if it is in autumn or winter season, because then, as there will be little fun to draw a warmth into the Tan, the moisture will prevent the fermentation, and the beds will remain cold; but in the summer season, there is no great danger from the moisture of the Tan. The heat of the sun through the glasses will be then so great, as soon to cause a fermentation in the Tan.
These Tan-beds should be always made in pits having brick-walls round them, and a brick pavement at the bottom, to prevent the earth from mixing wit hthe Tan, which will prevent the Tan from heating. These pits must not be less than three feet deep, and six feet in width, but seven is better; the length must be in proportion to the number of plants they are to contain, but if they are not ten feet in length, they will not retain their heat long; for where there is not a good body of Tan, the outside of the bed will soon lose its heat, so that the plants which are there plunged, will have no benefit of the warmth, nor will the middle of these beds retain their heat long, so that they will not answer the purpose for which they are intended.
When the Tan is put into the bed, it must not be beaten or trodden down too close, for that will cause it to adhere, and form one solid lump, so that it will not acquire a proper heat; nor should it be trodden down at the time when the pots are plunged into the beds, to avoid which there should be a board laid cross the bed, which should be supported at each end, to prevent its resting upon the Tan, upon which the person should stand who plunges the pots, so that the Tan will not be pressed down too close. When the Tan is quite fresh, and has not been out of the pits long enough to acquire a heat, the beds will require a fortnight, or sometimes three weeks, before they will be of a proper temperature of warmth to receive the plant; but in order to judge of this, there should be three or four sticks thrust down into the Tan, about eighteen inches deep, in different parts of the bed, so that by drawing out the sticks, and feeling them at different depths, it will be easy to judge of the temper of the bed; and it will be proper to let a few of these sticks remain in the bed after the plants are plunged, in order to know the warmth of the Tan, which may be better judged of by feeling these sticks, than by drawing out the pots, or plunging the hand into the Tan.
When the Tan is good, one of these beds will retain a proper degree of heat for near three months; and when the heat declines, if the Tan is forked up and turned over, and some new Tan added to it, the heat will renew again, and will continue two months longer; so that by turning over the Tan, and adding some new Tan every three months or thereabouts, as the bed is found to decline of its heat, they may be continued one year, but every autumn it will be proper to take out a good quantity of the old Tan; and to add as much new to the bed, that the heat of the bed may be kept up in winter; for if the heat is suffered to decline too much during the cold season; the plants will suffer greatly; to prevent this, there should always be some new Tan added to the bed in winter, when the heat is found to decline; but the Tan should be laid in a dry place a week or ten days to dry, before it is put into the bed, otherwise the moisture will chill the old Tan in the bed, and prevent the fermentaation; so that unless the Tan is turned over again, there will be little or no heat in the beds, which often proves fatal to the plants which are plunged in them; therefore whoever has the management of these beds, should be very careful to observe constantly the warmth of the Tan, since, upon keeping the beds in a due temperature of warmth, their whole success depends, and where this caution is not taken, it frequently happens that the Ananas plants run into fruit very small, or the plants are infected by insects, both which are occasioned by the growth of the plants being stopped by the decline of the heat of the Tan; therefore great regard must be had to that, especially in winter.
The great advantages which these tan-beds have of those which are made of horse-dung, are the moderate degree of heat which they acquire, for their heat is never so violent as that of horse-dung, and they continue this heat much longer; and when the heat declines, it may be renewed, by turning the beds over, and mixing some new Tan with the old, which cannot be so well done with horse-dung; and likewise the beds will not produce so great steams, which are often injurious to tender plants, so that these Tanbeds are much preferable to those of horse-dung for most purposes.
Tan, when it is well rotted, is also an excellent manure for all cold and stiff lands; and if it is laid upon Grass ground in autumn, that the rains in winter may wash it into the ground, it will greatly improve the Grass; but when it is used new, or in the spring of the year, when dry weather comes soon after, it is apt to cause the Grass to burn, which has occasioned the disuse of Tan in many places; but if properly used, it will be found an excellent dressing for all stiff lands.