You didn't mention sun requirements but tree mallow maritime aka lavatera should do great. It can get taller but mine hasn't. It likes a little shade in hot climates like mine and yours.
It has been blooming ever since I put in ground 1.5 years ago.

This may be a crazy, wacky idea...but how about a rose? That's why most people plant them, for their long blooming season. If it doesn't freeze where you are, it'll be pretty much evergreen.

If roses are too difficult, how about a rockrose (cistus)? Plant it and forget it. Evergreen, nice gray-green foliage, rounded habit, just about the size you want, doesn't care about your soil, super drought-tolerant, and really fragrant.

Backstory on rockroses: you know how in those statues the Egyptian pharaohs always have beards--even the female ones? Well, I read that actually they didn't grow beards, but their cronies would cut off the beards of goats that had been grazing on rockroses and paste them on the chin of the pharaoh, so the scent would always be with them.

Rock roses have a scent? Hmmm...I never noticed. I'll have to stick my nose in one.

Long blooming...what season? Rockroses are for a few months spring-early summer perhaps.
Roses do bloom longer, esp. if you get repeat bloomers.

If they don't freeze in your zone, the longest blooming shrub I can think of is Euryops. I think it only gets to 3-4' though, and needs regular pruning to keep it fresh and tidy.
Sweet pea shrub (Polygala) is a really long bloomer and may be hardy in your zone. It will get to about 5', I believe.

It will be in full sun till 5 pm, maybe to hot for tree mallow.?
We have over 50 roses, we want something different in this spot.
It does freeze here, sometimes hard.

Tim

The only one I can think of off the top of my head is cape mallow (Anisodontea x hypomandarum), but it only gets about 4' x 4'. It bloomed for me almost all year....before the gopher got it. If you have gophers, be sure to protect it! :)

My 2 rockroses have no scent (foliage or flowers)! Have I been robbed? Mine only bloom for about a month, and they're in full swing right now.

Brenda

Wanda is right about the polygala. I have one of them also.
It really flowered well this spring now since established.

Just remembered...I see a tree mallow everyday coming home in full sun all day and is doing fine here. It's probably been there couple years.

I had frost several times past winter and neither even noticed.

I also have a cape mallow but just put it in, but a neighbor has one and is huge. They arent gardeners so never been trimmed etc.

I would consider Cuphea 'David Verity' which is evergreen, although can be frozen back, and blooms constantly with hundreds of 1 inch orange flowers that hummingbirds love. In frost-free places it can get to be 8 feet tall, but occasional trimming could keep it smaller. It will survive fairly severe freezes, but would have to resprout from the roots.

If the spot doesn't get much water how about Dendromecon harfordii. I have one and it's almost never out of bloom -pretty yellow flowers that smell like fruit salad and gray green foliage.

My bad...not all rockroses are fragrant--cistus ladanifer (gum rockrose, with white flowers) is the most fragrant, and some hybrids with c. ladanifer background.

I'd be surprised if lavatera assurgentiflora (the one native to the Channel Islands) couldn't take a summer day in Sacramento--how cold does it get though? I think it's good down to 25 degrees, no more.

I like dendromecon harfordii (island bush poppy)...a really underused shrub. Beautiful foliage, too. Plant like bougainvillea, it hates root disturbance.

I know this is common as dirt, but nothing is easier or prettier in the valley than the dwarf oleanders petite pink or petite salmon. Evergreen, flowers non-stop from March to November, low water usage, staying under five feet, few pests.... If there aren't going to be any unsupervised toddlers nearby, I cant think of anything that would be as perfect to meet your requirement. "Little John" bottlebrush comes close but doesn't flower nearly as long.

Here is a link that might be useful: picture of petite salmon oleander

I have a polygala I bought at an Armstrong nursery last spring. I'm surprised at how tough this plant is. It went through our freezes and two feet of snow on several occasions with only a little tip damage. It seemed to never be out of bloom. Mine has stayed small, though, but might be my colder climate. Still very pretty and hardy - I think I'm going to try propagating it. Who knew I could have a flowering evergreen nearly year round! You need this plant! : )

Try a Galvezia: tough as nails, drought tolerant, bright red snapdragon blooms beloved of hummers. These are the best:
'Boca Rosa' - forms a dense mound with arching stems reaching to 4 feet tall. In the summer through early fall it produces tubular bright red flowers which are flared at the lip, resembling small snapdragon flowers. Plant in full sun to moderate shade in well-drained soil. It is drought tolerant, especially if planted in shade. foliage is a larval food source for our local Checkerspot butterfly. Prune occasionally for denser growth
'Firecracker' is more compact.

I would hesitate to recommend Oleander. It's been a beautiful standby and I never had to water established plants -Until Oleander Leaf Scorch arrived. My town used to have Oleander everywhere. They made gorgeous windbreaks. Lovely reds, pinks and white. I had an 80 foot hedge with pink, double camellia-like flowers. Other neighbors had the dark red variety. Now they're dead sticks or gone altogether.

The euryops can easily get big enough and do bloom over a long season. Choisya ternada have a main bloom in the spring with sporadic bloom through much of the year, and are very fragrant. Dendomecan harfordii get to about 6 feet and always seem to be in bloom. Al