Answer: Yes, you can use Round Up in a potential vegetable bed. There's a waiting period after using and before planting your veggies. Round Up deteriorates rapidly in the presence of sunshine and fresh air so there should not be any residual action past the waiting period.
The best way to discourage weeds is to use a mulch in your planting beds. You can purchase weed barrier and then cover it with bark chips or you can spread 3-4 inches of compost or other organic matter over the bare soil to prevent weeds. Or, you can use a pre-emergent herbicide. There's one that's corn-gluten based, and there are others with chemical bases. All do a good job of preventing weed seeds from germinating.
Best wishes with your landscape.
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