I was wondering if I can put a Zinia Giant Violet Queen seedling in a pot to let it grow and jus let it stay in the pot for a house plant or if they need to be outside I have 36 seedlings growing right now so I will need to know soon.
Zinnias aren't really house plants. They like full sun, which is hard to simulate indoors. If you have a good light set up and wanted to keep them in big pots under lights all the time, it's possible to grow almost anything indoors. But they are very easy to grow outdoors.