Q.do roots continue to grow for next harvest for veggies in soil
i am unsure as to whether roots for veggies like onions continue to grow and produce more onions once i have harvested the original onion produced. or would i need to plant new seeds for a new harvest.

Certified GKH Gardening Expert
No, once you harvest an onion, unless you physically saw replacement bulbs near it, they will not grow back. You will have to reseed, or you can use the bottom root portion of the onion once you use the onion to replant. That root section will turn into a cluster of onions if planted correctly.
This website will help: https://www.instructables.com/id/Grow-Onions-from-Discarded-Onion-Bottoms/