Plowing (Ĥoresh) involves preparing the ground for sowing or planting by loosening and softening it. Similarly, a person may not clear rocks from a field, level its surface, weed it, or fertilize it, since these actions improve the soil and make it easier to sow and plant.
Included in the prohibition of Planting (Zore’a) are watering, pruning, and doing anything which helps plants or trees to grow. However, one may open irrigation pipes or turn on sprinklers before Shabbat so that plants will be watered during Shabbat. Similarly, one may set a computer before Shabbat to activate sprinklers on Shabbat.
Reaping (Kotzer) is defined as cutting off a plant or tree from its source of growth. This includes harvesting grain and picking fruit, as well as breaking off a branch or leaf from a plant growing in a flowerpot or in the ground.
