That's because the pot sits on a large stone outside the garden walls.
There is only one plant in the ground in this area, a small sharkskin agave. The rest are cactus and agave in pots. It is a good spot for them to spend the summer months and adds interest to a rather bare area. The massive drystone wall was built by David to retain the slope that remained after the house was built. I would love to have plants growing from the wall but I think a lush wall planting here would look inappropriate.
