Hammocked Banana

So I was going to build my DF trellises in their final resting pots today and ran into an issue. I am going to use two 6' cedar 2x4s nailed together to make the central post, with a top support made of 1x1s. I'm going to screw the post through the bottom of the pot with washers to hold it down, and screw 4 more pieces of 1x1 to each side of the post to brace it to the side of the pot. These pieces will be under the soil level and will not be seen, but will hold the post up plum. These might rot away eventually but after many years the roots in the pot should help hold up the post (or I will make a new trellis pot by then). I'm also probably going to either wrap the post in burlap or 1" rope to give the roots something to hold on to.

I am worried about the cedar post rotting in the soil if it stays moist. I initially went with cedar because I know it naturally resists rot and because it will look decent when in the house all winter. Should I be worried about it rotting? Can I treat it with something that is ok (non-toxic) to be in the soil? I would probably then also treat the 1x1s under the soil. Any other advice on my plans?