This isn't actually construction but I thought that the construction-brains would be the ones with the knowledge that could come up with a solution.

I'm making trees for a wedding venue. The trunks are made from 4" diameter PVC that's 5' long. It'll be sitting inside of a 14" diameter clay pot. I've glued a 4" PVC floor flange into the bottom of the pots. The fit isn't as snug as I'd like which I can remedy by wrapping the flange or the inside of the 'trunk' with duct tape but I think they still need some sort of bracing that will keep them upright and plumb that can be done and undone (for transportation purposes), relatively quickly & inexpensively.
Some of the things I've considered are :

Bags of stones but if there were something less weighty my back would appreciate it.

Drilling 4 holes into the clay pots & the PVC and running a wire through the center at right angles but I'm afraid that drilling a hole would stress the terracotta causing it to crack.

Gorilla tape-could work but I'm not sure I trust the strength.

Just so you have the complete picture, the branches of the trees will be made from actual branches I've harvested off tree lawns as the power company has pruned trees all over town. Then a couple sets of twinkling white lights. So the weight isn't substantial but the height and reach will definitely call for something to stabilize the trunks in the pots.
Thanks in advance for any ideas.
Marci

OK... one thought. Could always drill 1/2" holes perpendicular to each other through the pipe and use 3/8" threaded rod (sold at home supply store... cut with hacksaw) or sticks to pass through and act as levers in each direction... would need to cover with a mulch or similar. Just an idea.

And a 4" flange should fit 4 inch pipe tightly... maybe if you cemented the pipe using PVC cement? Good luck.

Isn't there plastic flower pots that look like clay pots?