Hi , i know i said i was done save the plastic but i got to thinking and put in a center post. Advantages = i can use plywood and make a built in table, tile it with left over metro tile, and hanging plants, a plant shelf, if i do put a table there it would be easy to do a few 6 inch plant shelves near the top. and i had to put furring on the rafters 2 x 3 was the cheapist thing home depot had that had strength, they have horrible expensive 2 x 2 's there. heres some photos
grapes grow fast, i am happy