It is believed that the proper time to plant these types of crops is during the waning phases of the moon or the third quarter moon. This is the time during which the face of the moon is decreasing from a full moon to a new moon.
For the planting times in your area see the Moon Phase Planting Zones chart.
Below ground crops include some of the main staples of the vegetable kingdom. They are high in nutritional value, easily grown and tend to store well. Known as root vegetables, these plants produce their edible portion or roots in the dark underworld of the earth.