Knocking on heaven’s door
What some people throw away may be the treasure for those who find it, and such is this case. If you are walking down the street and find drop-down doors that someone discarded, you can take them and create a pillar to hold your plants.
Clean it properly, give it a few layers of paint and take it to the best place in the garden. Recycling is the solution again, and you’ll have a great stand that only costs you a walk and some paint. Practically nothing!