The crop of the first year is small, and sometimes not worth manufacturing; that of the second year is the best, and the third is also very good, if it has been carefully weeded; but many indigo fields have lasted more than ten years without being re-sown, as the seed which falls naturally springs up again, and where the land is good yields nearly as large a crop as a new sown field.  When the plant is ready for manufacturing, a number of men are collected, each of whom is either provided with, or brings his own mule or horse, if he has one.  Two men always go together, cut the plant, then about the height of full-grown red clover, and take it to the vats, which are large tanks made of brick and lime, holding at least 1,000 gallons, and some as much as 10,000.  Into these the plant is thrown till they are nearly full, when weights are put above it to prevent its floating; and the vats filled with water till it covers the mass of the indigo plant.  After remaining from twelve to twenty-four hours, according to the state of the plant, weather, and other circumstances (the time required being determined by the color which the water assumes), the herb is taken out, and the water beaten with paddles in the very small vats, and by a wheel suspended above and turned by men or horses in the larger ones, till it changes from a green color, which it has acquired ere the removal of the herb, to a fine blue, when it is allowed to stand for some hours, till the coloring matter has settled to the bottom of the tank, a process which is generally hastened by throwing in an infusion of certain herbs to facilitate its settlement, or as the natives term it curdle (cuajar) the colored water.  As soon as all the color has settled, the water is drawn off, and the blue, which is of the consistency of thick mud, is taken out of the vat and spread upon cotton, or coarse woollen cloth, and dried in the sun.  The color in a great measure depends upon removing the herb exactly at the proper time, and upon properly beating the water, neither too long, or too short.  Unless these processes are properly performed, the indigo will not be of first-rate quality; but some estates will never produce the best indigo, whatever care may be bestowed on the manufacture.

A mansana, of 100 yards square, which is nearly two British statute acres, produces generally about 100 to 120 lbs. of indigo, the carriage and cutting of the herb costing about twenty dollars, and the cleaning of the field and all other expenses connected with it, including the manufacture of the indigo, about as much more.

The indigo of Central America is not put into moulds when drying, as that of Bengal, but is allowed to remain in the rough shape in which it dries, and without further preparation is ready for baling and exportation.