Take an old angel food cake pan and cut it about an inch from the top of the center tube and rolled edges. Slip the umbrella pole of your patio table through the angel food cake pan. The container can then be filled with fresh plants.
To keep the plants from getting water logged, drill a few holes in the bottom of the pan for drainage. If this causes the container to leak on the table too much you can easily remove the planter and place it on the patio floor, when it’s finished dripping, put it back in place on the patio table. If you like you can spray paint the cake pan first to decorate as desired.