You can get some old screen doors....the kind that has like 12 or 14 small panes of glass in them. Pop out the glass (might have to break the glass to get it out) and then screw in 3 pieces of wood....like 1x1 or something....that is about 2 feet long into the bottom of the door. Give the doors a fresh coat of paint or two and then put the posts of wood into holes. Depending on what you have growing
on the trellises, you might want to add some cement into the holes to keep the trellis from falling down.