The Crape Myrtle and Plumbago 'Royal Cape' or much more drought tolerant than the Pentas, so grouping with Pentas will kind of lock you in to water loving things to keep the Pentas happy. Deeper blue flowers of Agapanthus 'Elaine' or 'Storm Cloud' would work well, or you could also use the deep blue flowers of Aristea ecklonii or Salvia 'Indigo Spires' or the dwarfer growing Salvia 'Mystic Spires'. Or you might consider blue foliage of the California native grass, Leymus condensatus 'Canyon Prince', or Helictotrichon sempervirens. Another blue foliaged ground cover you might consider would include Senecia mandraliscae/Blue Chalk Sticks at the foreground, or the blue flowered Scaevola aemula 'Blue Wonder'. Some silver foliage accents in the mix could also work well with the pink/blue, such as Astelia chathamica/Silver Sword at the back, and/or Festuca ovina/Blue Sheep Grass at the front.

To my mind at least the best color with plumbago is white. A white crape myrtle would have given a cooling effect in an area that gets a lot of hot sun. Is there a chance you could move the pink crape myrtle to another location? Blue and white agapanthus might also enhance the scheme. White shrub roses (Iceberg, Pillow Fight, Sally Holmes, Mme. Joseph Schwartz) might also enhance your planting. Perhaps an architectural feature such as a birdbath in a classic design might be a focal point of your scheme.

Ingrid

Hey, what a coincidence! I have the exact same scenario! Theres a wedge shaped bed 30 feet long and about 12 feet wide on the wide end, and i am also in zone 9. I have already filled the area in with plumbago (from seedlings that sprouted under an existing bush) and planted a line of Erythrina Crista-Galii (grown from seed). I also added three blue potato bushes and three Canary Island Date Palms (volunteer seedlings found in my yard planted every ten feet). Overall, theres a blue-red-Purple theme throughout the area. Everything is still fairly small, so i planted some cannas for quick color. For texture, I've planted Agave Desmettiana (found at a discount Dollar Tree Store) and some Daylilies. The best part is that i only had to buy the blue potato bushes and the Agaves because everything else was available from my own yard. I will definately post pictures when i get a chance.

Stop thinking of just flowers, and get into interesting and contrasting foliage plants! (Photos below identified L-R)

Strobilanthes, Pelargonium, bearded iris leaves
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Plectranthus, Oxalis siliquosa
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variegated CA fuchsia
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Nasturtium, bearded iris leaves, variegated aucuba 'Gold Dust', artemisia 'Powis Castle', lamium maculatum 'Purple Dragon'
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Heres a couple of pics from the area that i'm landscaping that sounds similar to yours. This first one i drew on to show the color schemes once all of the plants become established. The blue is the plumbago, the red is erythrina crista-galii, the purple if potato bush, the pink in the back is oleander and the three green dots are where i have planted Canary Island Date Palms at 10 feet apart.
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Here are two more shots.
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Hi Central cali369--
I am a big fan of palms, and and like to see them used in landscapes. Could you check the name of your palms? A Canary Island Date Palm, Phoenix canariensis, while very slow growing, will get a big fat trunk and 50-foot spread at maturity. Very few palms will disturb a house foundation or block wall, but Phoenix canariensis eventually gets so huge that it can. I'm guessing you really have Pygmy Date palms, Phoenix roebelenii, which remain relatively small and slender, even into old age. But if you really do have the big ones, give them a lot of room, as they are difficult to move when they get large and the spines are fully developed. My palm book lists the trunk diameter at 2 to 3 feet.

The second cautionary tale is the Erythrina crista-galli. It's one of my favorite trees, but will grow at least 15-20 feet high. If that's what you are expecting, that's fine, but they won't remain the size you have sketched above. But maybe you have something else, a different name?

I only mention this because I have learned the hard way to research and believe the eventual sizes of plants.

I like the tropicalismo you are developing, the dark-leaved cannas look great.

Catkim, thanks for the insight. Yup, i did a bit of searching around for information before planting these here. The palms are definately Phoenix Canariensis, i have Phoenix roebelenii planted elsewhere in my yard as well. {{gwi:8309}}
My street is lined with majestic, old phoenix canariensis and the birds drop their seeds all over my yard, so i get volunteer seedlings all of the time. The bed is roughly 25 to 30 feet away from the house, so the canariensis will have plenty of room to grow. Now that you mention it though, i will make sure there is enough room between the phoenix and the wall. The phoenix on the pointed end of the bed has roughly 2 feet on all sides, the photo just doesn't do a good job of showing it. Heres another photo showing the distance from the house and patio. The patio itself is 30' long by 12' wide, and the strip of lawn is a bit wider than the patio.
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About the crista-galii, the biggest i have seen them here in Fresno is less than 10 feet tall. And that's in the older neighborhoods of town. They are kept smaller maybe by the handfull of frosts we get here every winter (?). In either case, i'll probably be trimming it ocassionally to keep it on the smaller scale.

again, thanks for bringing this up.

Ah, I hadn't thought about frost keeping the erythrina smaller, good point.

Since the date palms grow on your street, you know how big they get, and you're right, 'majestic' is the word! Here's a younger one with some people in the pic for scale -- you can see how bulky they are:

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Sorry for the hijack, kigmy! To get back on topic, how about a triple planting of the little pygmy date palms to balance the crape myrtle? And I agree with jkom, some contrasting foliage plants might add more to the look than "matchy matchy" blue flowers that blend into the plumbago. That variegated aucuba would be very nice!

Kigmy, just one thing about the variegated aucuba, they don't like sun too much. I had one that burned in full sun until noon. I had to move it to a shadier spot.

Yes, sorry, I should have mentioned that - aucuba and lamium prefer partial shade spots. They are perfect under dense higher-growing plants, however.

Thanks, everyone, for the wonderful suggestions!

What's wierd about this planting area is that end of it has terrible drainage and the other end can be quite dry.

For the dry end, I've got a grouping of agapanthus "midnight blue" - the darkest blue I could get my hands on, so that it will stand out against the plumbago. And I added caryopterus "dark knight" around the base of the crape myrtle. With that, one end of the bed is filled in.

The wet end is still empty. I added 36, 40 pound bags of topsoil to this bed in an attempt to raise it up out of the muck, with no success. I really can't bear the thought of digging it all out and putting in a drainage system. So - only plants who like their feet wet will be going in on that end. Irises in the back, dwarf ruellia and bacopa in the front.