Here in hot so. CA, I found the roots and stems close to the ground must absolutely be shaded. Niobe thrived for years with a rose planted in front of it that gave it the shade it needed.

Its location means its getting a lot of reflected heat. Not good for a clem, especially for the lower leaves.

A light cut back after each round of blooming and an additional hit of fertilizer at that time stimulates fresh growth that looks good longer and gives a chance for more flowers. Plus plenty of water.

Thanks for the advice!

I think I'll try more regular cutting back, adding compost, and giving it more water for a year. If that doesn't improve matters I'll replace it next fall, but I have no idea what else could go in that spot.

Yup, it's the "hot feet" that are giving your clematis trouble. They like sun on their heads but shade on their roots. Not a warm soil plant.

I've actually found several sources that argue the 'cool feet' thing is a myth, rather than being crowded by other plants they would prefer well mulched and consistently moist soil. The path is about 4 inches deep, so I figured under the warm top layer of DG the soil underneath should actually be pretty cool. It's almost like being planted in a pot, out on a patio.... in the heat.

Anyways, there isn't much else that I can plant there so I'm going to try more compost and running an irrigation line under the DG.

Have you ruled out end-of-season look?

Nope, I'm hoping that is not the problem but suspect that it is.

Last year I planted the vine in September, so it was looking quite nice for the fall. This is its' first full year in the ground, so I don't know if this is a normal pattern, a reaction to stress from underwatering, or something else.

I would pull it out and put something else in its' spot, but I can't think of any other vine that won't overwhelm my 7' tall obelisk trellis. The spot gets lots of sun between the spring and fall equinox, and much more shade between the fall and spring.