So I finally got all of the walls in place.
This picture shows the central dividing and front wall for the veg room in place:
This picture shows all of the walls in place - veg room on the left, flower room on the right:
So, you may be saying to yourself, "why did he build two separate walls for the entrances, when a single wall would have done the trick?"
Indeed, one wall would have been much easier to build and keep straight. However, my basement is very crowded and I just didn't have the space to easily build a single 10' wall. Sure, I could have built the wall in place, but I find building the wall first and fitting it into place is easier. Thus, I had to go with two 5' walls. And no, I didn't get them lined up just perfect. There's a slight twist where the two walls meet in the center. If I was going to hang drywall, this could potentially be a problem.
BTW, those openings will hold a 30" door, should I ever decide to install them. Plenty of space to actually get stuff into the room, including the tables that I've built (well, one table so far).