Colonial officials encouraged planters to invest in indigo production by providing subsidies and assurances that it would be a lucrative venture. Harvesting and processing a successful crop, however, required skill and tremendous physical labor. In the following passage, George Milligen-Johnston, a Scottish-born physician who immigrated to South Carolina as a young man, explains the processes required to ferment and dry indigo. His description indicates some of the challenges that indigo planters faced and the work required of their slaves, though he does not state who is performing the tasks he describes.
In Carolina we generally begin to plant about the beginning of April, in the following manner: The ground being well prepared, furrows are made with a drill-plough, or hoe, two inches deep, and eighteen inches distant from each other, to receive the seed, which is sown regularly, and not very thick, after which it is covered lightly with earth. A bushel of seeds will sow four English acres. If the weather proves warm and serene, the plant will appear above ground in ten or fourteen days. After the plant appears, the ground, though not grassy, should be hoed to loosen the earth about it, which otherwise would much hinder its growth. In good seasons it grows very fast, and must all the while be kept perfectly clean of weeds. Whenever the plant is in full bloom it must be cut down, without paying any regard to its height, as its leaves are then thick and full of juice, and this commonly happens in about four months after planting. . . . When everything is ready, the weed must be cut and laid regularly in the steeper [vat] with the stalk upward, which will hasten the fermentation; then long rails must be laid the length of the vat, at eighteen inches distance from one another, and wedged down to the weed, to prevent its buoying up when the water is pumped into the steeper. For this purpose the softest water answers best, and the quantity of it necessary must be just sufficient to cover all the weed. In this situation it is left to ferment, which will begin sooner or later in proportion to the heat of the weather and the ripeness of the plant, but for the most part takes twelve or fifteen hours. After the water is loaded with the salts and substance of the weed, it must be let out of the steeper into the battery, there to be beat; in order to perform which operation, many different machines have been invented; but for this purpose any instrument that will agitate the water with great violence may be used. When the water has been violently agitated for fifteen or twenty minutes in the battery, by taking a little of the liquor up in a plate it will appear full of small grain or curdled; then you are to let in a quantity of lime-water kept in a vat for the purpose, to augment and precipitate the fæculæ [starch], still continuing to stir and beat vehemently the indigo water, till it becomes of a strong purple colour, and the grain hardly perceptible. Then it must be left to settle, which it will do in eight or ten hours. After which the water must be gently drawn out of the battery through plug-holes contrived for that purpose, so that the fæculæ may remain at the bottom of the vat. It must then be taken up, and carefully strained through a horsehair sieve, to render the indigo perfectly clean, and put into bags . . . and suspended for six hours, to drain the water out of it.After which the mouths of these bags being well fastened, it must be put into a press to be entirely freed from any remains of water, which would otherwise greatly hurt the quality of the indigo. The press commonly used for this purpose is a box of five feet in length, two and a half wide, and two deep, with holes at one end to let out the water. In this box the bags must be laid, one upon another, until it is full, upon which a plank must be laid, fitted to go within the box, and upon all a sufficient number of weights to squeeze out the water entirely by a constant and gradual pressure so that the indigo may become a fine stiff paste; which is then taken out and cut into small pieces, each about two inches square, and laid out to dry. A house made of logs must be prepared on purpose for drying it, and so constructed that it may receive all the advantages of an open and free air, without being exposed to the sun, which is very pernicious to the dye. For here indigo placed in the sun in a few hours will be burnt up to a perfect cinder. While the indigo remains in the drying house, it must be carefully turned three or four times in a day, to prevent its rotting. Flies should likewise be carefully kept from it, which at this season of the year are hatched in millions, and infest an indigo plantation like the plague. After all, great care must also be taken, that the indigo be sufficiently dry before it is packed, lest after it is headed up in barrels it should sweat, which will certainly spoil and rot it.
Source: B. R. Carroll, Historical Collections of South Carolina (New York: Harper and Brothers, 1836), 1:387–89.