And covered to a depth of three or four inches

And covered to a depth of three or four inches

Like other crops, potatoes need a thoroughly prepared seed-bed and intelligent cultivation. Break the land deep. Then go over it with an ordinary harrow until all clods are broken and the soil is fine and well closed. The rows should be at least three feet from one another and the seeds placed from twelve to eighteen inches apart in the row, and covered to a depth of three or four inches. A late crop should be planted deeper than an early one. Before the plants come up it is well to go over the field once or twice with a harrow so as to kill all weeds. Do not fail to save moisture by frequent cultivation. After the plants start to grow, all cultivation should be shallow, for the roots feed near the surface and should not be broken. Cultivate as often as needed to keep down weeds and grass and to keep the ground fine.

Source: Agriculture for Beginners