Have you considered Nandinas? I happen to like them for difficult spots like this. Well, I like them for a lot of spots.

They are tall and narrow, won't flop, drought tolerant, white flowers in spring, red berries in winter, evergreen leaves that turn red in winter, no diseases, faithfully always there. A nick name for Nandina is 'heavenly bamboo', which I think it deserves.

I have a similar bed...we call it the Sahara. It borders concrete.

What has succeeded there that is tall? Well, it helps to have a soaker hose in it.

Flame acanthus, that purple fountain grass, I think Tithonia would be happy, if you have enough water and some shade horse tail. Mine has gone wild in a spot that gets wet from a drip in the hose. But it added interest for several years when it was really dry.
Mexican honeysuckle...doesn't look like honeysuckle but that's what was on the label.

amy:
Bush Germender (Teucrium fruticans)evergreen and easy to prune.

Red Yucca (Hesperaloe parviflora)evergreen w/soft leaves
there is also a yellow form (you have to look for this one)

Bicolor Iris (Dietes bicolor)evergreen will need some water
during our dry summers.
I suppose it also depends on how tall you want your plants to be.
Kind of a small bed for some of theses plants. The canna's
would need dividing every year.

If you can fint it "Will Fleming" Yaupon Holly (will need some supplemental water also.
Art

I'd research all suggestions well, with particular attention to the appearance and size of the mature plant.

If you can widen the bed a couple of feet, upright rosemary might be your best bet--evergreen and some summer color. Since you're planting against a concrete foundation, you might raise the bed a little by working in some soil amendments. Gulf Stream nandina would also maintain at 30 to 36 inches without a lot of fuss and bother. No blooms or berries, though, and I haven't tried to grow it in full sun.

Thanks whitecap, I like the nandina suggestion, and I have one nearby so I know it would do fine. And I widened the bed yesterday after realizing it was impractical to fit anything very tall with so little depth. Right now I'm thinking either:
- A combination of red yucca and flame acanthus with silver ponyfoot in between
- A nandina (probably Gulf Stream)
- Bush germander or Texas sage

does it need to be evergreen? you might try something like basil. they get big and love the heat. You can also mix in cosmos for color. or sunflowers.

Standing cypress would be pretty.

Maybe clumping bamboo? After dealing with termites recently, I wouldn't plant anything too close to the foundation.

Nandina is frowned on in Austin because they are invassive and the birds love to carry the berries into the wild parklands. Clumping bamboo might do a number on your foundation. Lavender hates clay soil. Rosemary will need ammendment if the ground is clay but will not be as picky as lavendar. There are small agaves (A. parryi var truncata, A. Lophantha quadrifolia, X Manfreda Macho moca, Yucca glauca, Pale leafed yucca; Yucca pallida) that will go with the Red false yucca. Make sure you get the small one. Some of the hesperaloes that they have get large while others stay compact. The ground will need some drainage added to it.

Some salvias will love that spot. Salvia gregii, Grey oak sage salvia macrophylla, also Mexican oregano (good in beans).Firecracker fern, Maximilian sunflower.

I'd plant salvias there.