Agastache is a good one and long blooming too. I have both ‘black adder’ and ‘blue fortune’. Garden phlox, Culver’s root, Echinacea purpurea also come to mind for something tall. Sidalcea ‘candy girl’ is a real trooper too.

I haven't had much luck with tall phlox in the past, but I do love the look

Curious..what problems have you had with phlox?

I have several pale yellow Helianthus microcephalus Lemon Queen, a slow spreading resilient perenial sunflower.

the pale yellow could perhaps go with a bright yellow,

the plant itself is great, up-right, not flopping, flowering for a long time, last summer was brutally dry in our region, they got by with ocasional water (1/week or less)

height somewhere between 4 to 5+ feet (shorter in drier soil :-) )

and they are fairly lonlived

Perovskia! Several years ago, on a rather long (seemingly endless) car trip across the west, I was enchanted by the perovskia. It's a much darker color in the western US.

Wondered if verbena bonariensis is hardy enough. Phlox and Joe Pye weed have been dismal failures for me (an arid climate and sandy soil),,,but the taller dianthus (carthusianorum, pinifolius) have been good...as are quite a few penstemons. Some of the asters have been OK, once fully established. Eryngiums are a varied and to my mind, thrilling genus and will second perovskia.

How tall? Several salvias (black and blue or Amistad or Mexican bush or Salvia azurea) could be good...they don’t seem to need as much water. I also deal with western sun from midday to sundown. It can be fun. Lol

I tried Joe Pye Weed...it didn’t make it.

Love your username!

I second the salvia suggestion, many varieties would work. Another idea is some sort of ornamental grass.

What about tall tickseed (Coreopsis tripteris)? Or some varieties of hibiscus.

Liatris, Ratibida and Veronicastrum are some other options. I'll second the recommendation of Salvia azurea, although it tends to get pretty floppy while in bloom unless you pinch it back earlier in the season, but then you're also losing some of the height.

I'm looking for something over 4' or so.

I've have Russian Sage and its wider than what I'm looking for in this particular spot. .Its a great plant here in the west , but it is slow to wake up and honestly looks like a drab gray mess when its not in bloom. I also have agastache in my garden and its more like 2' tall for me.

My experience with tall phlox in my garden is that it starts out fine but gets bare legs and yellow leaves. And it didn't return as I recall, but I did significant changes the following season so maybe I did something, can't remember. I think I will try it again in the garden.

On a whim last night I ordered 6 Verbena bonariensis from Bluestone. I looked it up and while it may not be hardy enough it should reseed, at least I hope so. I actually recently saw this plant on one of my favorite Monty Don gardening shows and was excited to see that it might work in my climate. I am concerned that the nurseries here don't carry it, I hope that doesn't mean it will be a failure.

Achillea, phlomis, sanguisorba, sidalcea, argemone, crambe, oenothera, verbascum

Ornamental grass

maximilian sunflower, rabbit bush, Nepita

Do your research on suggestions. Quite a number of the suggestions are actually wetland plants (phlox, hibiscus, Joe Pye Weed, some liatris) I don't think they would at all fit an arid landscape.

Agastache has many varieties, and some of mine are well over 3’. I would expect that you should be able to find some Salvias and Penstemons that fit your requirements as well. You may need to look for species plants rather than garden cultivars that often are selected for shorter sizes. Check out whether Caryopteris ‘Snow Fairy’ is tolerant enough of dry conditions - variegated leaves and late season blue flowers.

dbarron - Which Liatris are wetland plants? I have three species on my property (spicata, pycnostachya and ligulistylis) and I haven't watered a single one in years, despite several droughts over the last few summers.

all three of those liatris are "normal" land liatris. Liatris pyncostachya grows in ditches of east Texas to the Backland praries, not the western half of Texas where I live. For Utah and New Mexico , one should look for Liatris muncronata and Liatris punctata.

So many of these 'prairie species' turned out to be hopeless, liatris included., for me. The level of aridity in the east of England can be quite startling - in line with Israel or Arizona (around 24-28inches per annum). Also of consideration, I have found, is actual depth of useful topsoil. I can grow rudbeckias in my root infested, dry woodland, because the soil is deep enough for the fat, foraging, roots to go deep enough to reach the water table. My allotment, on the site of a gravel pit, has been a hopeless fail requiring constant hosing, even if the roots grew to Australia.

I recall sourcing liatris mucronata seeds but giving up on them before sowing - might have to rummage in my seed boxes and try again.

Agree 'mara. Gotta be careful with eastern definitions of full sun and arid when dealing with the West, or SouthWest.