Why, out-of-doors, of course! In the soil. Vegetables did not need houses.
[he gestures to the garden behind him]
As you can see, they have thrived in this temperate weather. As the air cools, however, perhaps the construction of this 'greenhouse' structure would be a prudent thing to consider. I remember that cold, wet substance called 'snow' that fell from above not so long ago—I do not think vegetables can grow under such stuff.