@eastwoodandy that sure looks like a very hard to reach window. Personally I agree with what others said about using either a container with water reservoir or use artificial plants. Way too risky to climb any ladder at that height.
Or you can use solar dancing plant decors so that window shows some life when some bright light hits it.
We have a similar situation at home, and ours are not even cathedral heights yet, but it takes me awhile to check/do watering, so we opted for containers with water reservoirs, and I also chose plants that will not be too water/light needy. We also do not want to block the windows too much so we have a floor to ceiling plant stand. Even at this lower height I get lazy, even my husband gets lazy to water, so the water reservoirs helps a lot:
And these ones are my solar dancing decors which decorates our north facing bay windows. Easy area to reach but I opted to have them there to make the area look a bit animated.
But if you do really want to put a plant there..my suggestion, maybe a ZZ plant, I hope that window ledge has enough space. That is one plant that can take much longer intervals, even months to need follow up watering.
