I guess another option might be to try to join them so that the finished length might be 6x16? maybe the only thing you would have to leave off (or not) would be the sliding door on one of them? or if you left the door in place, you could close one section (one 6x8)off?

Then maybe all it would take it to build some kind of "bridge" between them?

I'm really hoping that this could work....

I don't know how side-by-side would work (and my math gives me a 12x8), but the end-to-end configuration can be done - and has been done by at least one poster in this forum. I can't recall just now who it was, but tonight will try to search it out and post a link.

The door could not be left in place, as it slides to the side ... there'd be no place for it to go (except through the roof!). A small open doorway, however, can easily be covered so one can maintain slightly different temperatures in the two halves. Each winter I hang long, wide strips of leftover solar pool cover material, slightly overlapping, just inside the door of my 6x8. I find this greatly reduces drafts. On warmer days, I can open the door for better ventilation and ease of access, yet the strips prevent harsh drafts.

With a side-by-side configuration, unless you were to completely reconfigure the roof (and I don't know how that would hold up, especially to a snow load) you'd have them draining toward each other, and would have to duck down through a 4' opening to move from one side of the greenhouse to the other.

Maybe someone else has some other thoughts on this, though.

I believe milwdave joined two 6x8' HF greenhouses together (end to end)...here's a link to his photos. If he doesn't wander into this thread you could send him an email...
Milwdave's HF photos

I would agree with agardenstateof mind, seems like joining them end to end would be the path of least resistance! :-)

If I was going to do that I would put them back to back and then you would have a door at both ends.
Just leave a panel out of the back of both and
You could open both ends and have flow through ventilation

hahaha...I just 'wandered in'.:)

Joining two together was easier than I thought. I simply left off the door assembly of one greenhouse (but building the wall as normal) and the rear wall of the other. Drill a few holes to match the two structures and it's a done deal. Unfortunately I took no pics as I was running late in the season and just finished prior to the first hard frost.

Dave
Milwaukee

I happened to save this one.
RobsNewJersery double HF

{{gwi:291004}}