HH joined the wood corner of the bench together with biscuit joints.
We connected the bench to the planter with flat bar that we had welded on and with lag screws from the inside of the planter into the end of the wood. We also sealed the wood to slow decay. I bought a dwarf fountain grass (Pennisetum alopecuroides "Little Bunny") and grabbed a few plants I had on hand for the planter, the plants will likely change at a later date. I'm now waiting for the rusty patina to happen. Below you can see the completed project with my mini-assistant as the model.
Now when I find the time to take a break from gardening, I have the perfect place to sit....so far I haven't found the time!