Jains avoid root vegetables mainly because of the principle of ahimsa (non-violence) and the karmic consequences of causing harm to living beings.

• By pulling up a root like potato, onion, garlic, carrot, or beet, the entire plant is uprooted, often killing many tiny organisms in the soil. This is seen as unnecessary violence to living beings that share the plant’s life.
• Jain scriptures emphasize minimizing harm to all sentient beings, even the tiniest life-forms in the soil, and root vegetables are considered to involve more uprooting and injury than vegetables grown above ground.
• Leaves, fruits, seeds, grains, and tubers that grow underground but without killing the whole plant (or that can be harvested without uprooting the plant) are often preferred, while roots are generally avoided.
• There are small differences in practice between Digambar and Shwetambar communities, but the overarching ethic of non-violence and careful respect for all life keeps root vegetables widely avoided in both paths.

In short: the avoidance of root vegetables is about reducing harm to living beings and aligning daily food choices with the Jain vow of non-violence.