Why are potatoes ridged up with earth?

Why are potatoes ridged up with earth?

• Earthing up potatoes stops the light getting to the growing tubers. If potatoes catch light, they turn green and they should not be eaten.

• Earthing up potatoes into a ridge improves the yield of potatoes. It is better to have soil on the shoulder, rather than taking the ridge to a sharp point, because the potatoes grow in the shoulder of the ridge.

If the row is 30 inches wide, the ridge is usually about 6 inches above soil level. Any higher and the soil runs down as there is a natural angle of repose. The top of the ridge needs to be 4 or 5 inches wide.

As the stems grow, they are covered with earth two or three times, so a ridge develops.

What is the ridge made of?

• Soil from between the row is used, traditionally. This is why the potato rows are quite wide, so that there is plenty of soil available. A row 30 inches wide allows plenty of soil for ridging up.

• Any compost will do for covering the growing stems & earthing up

• Black plastic may be used.