While growing vegetables on the Alpha map (during early release), vegetables can be grown in the garden, and stored in an attached building.
However, they will never go to market. The market can have nearly 400 potatoes in it, but it will always show 0 vegetables. Vegetables can be used over time by trucks, but they do not appear in the market. I think it may be a compounding issue, as the longer I play, it now seems I can't get rid of any vegetables from a storage container I'm trying to deconstruct. I have about 7 hours on this map.