Hello George, your post has been sitting high and dry here at the top, so I thought I'll respond. My climate is not as kind as yours, I'm in the Illinois Valley about 20 miles north of the California border. I would give an eye tooth to be able to garden in your climate and grow some of the more tender South African plants and bulbs.
Do you give your Melianthus a deep watering every few weeks? I am sure that it would help them. They make wonderful container plants, you know, and if your soil is that poor you might consider placing them in tubs. Mine grew very happily for years in a half wine barrel and made a beautiful strategic display.
Welcome to the group, and please visit often. Your post got neglected, i think, because it focused on a small region with very small population. It is fantastic that you can even grow some aloes. Looking forward to more input from you! Delina

Delina is right about the neglect your post got, I had meant to reply with a few questions, but then it slipped my mind.

In particular I wonder if Schizostylis coccinea might actually do better in Oregon and Washington than here in northern California? The plant certainly grows well enough here, and flowers reliably, but almost all plantings seem to develop a nasty case of rust on the older foliage after the first season, and even with regular grooming, it is never a neat looking plant. I wonder if colder winters and more rain are not more to its liking, and result in a better appearance, as I have never heard this problem mentioned by gardeners growing this in England or New Zealand's south island.

Does Aristea ecklonii also seed as aggressively around the garden in your conditions? I like this plant, but without deadheading to prevent seeding, it can really take over in a summer irrigated garden here. I am also growing Aristea major at present, but it is not nearly as fast growing or prolific a grower here, and the various dwarf species of Aristea I have tried have always died out after the first year. I am hoping that eventually A. major will clump and bloom for me, as it is beautiful in bloom at Strybing Arboretum in Golden Gate Park, and it seemed to grow under such a wide range of conditions in the mountains surrounding Capetown.

Your nutrient poor and summer dry soil is actually quite similar to large areas of the Cape Region, particularly if you have sandy conditions and slightly acidic ph? Combine that with summer fog and constant wind, and you are probably not that different from higher elevation areas near Capetown, which can even get the occasional snow and frost. I remember being surprised to see how much snow was visible on the upper peaks around Capetown when I was there last August/September, as well as along the mountains while driving up towards Namibia. Admittedly at lower elevations near the ocean, the climate was more similar to San Diego/Los Angeles than San Francisco, but with a lot more regular wind!

With regards to Melianthus major, I have seen it in habitat in very hot dry situations, but generally think of it as preferring moisture retentive clay loam soils and some late afternoon shade to look its best here in the SF Bay Area, if it is not getting much summer irrigation. The growth can be so rampant here, it may be a blessing that it doesn't get 12 foot tall each season and require regular thinning/pruning to keep it manageable.

Some of the succulents you mention aren't much seen here, such as Aloinopsis, Ruschia and Stomatium. Instead we have much more of the brilliantly colored Lampranthus specatabilis and L. aurantiacus, and a few Delospermums. I am enjoying the flowering of Aloe saponaria and A. striata right now, and really like the yellow form of A. saponaria, which unfortunately doesn't seem as vigorous. A. marlothii does well in my garden as well, along with A. glauca, A. 'Blue Elf'(in bloom), and A. plicatilis, also in bloom. Aloe polyphylla also does well here if protected from excessive winter rains, or tilted on its side in winter if kept as a container plant.

Have you attempted any of the Leucadendrons or Proteas in your garden? I am not sure whether you get regular frost and generally stay above 25F in your location, or not. I have lost most all of my Leucospermums at 25F, but the Leucadendrons(apart from L. argenteum) have fared better, and Protea 'Pink Ice' has been totally unaffected by freezes down to 20F, if allowed to harden off new growth before a freeze.

Much more frost tender, (also lost at 25F), but currently in full bloom here at the moment are the wonderfully fragrant Psoralea pinnata, with sweet pea like flowers that smell like bubble gum and soft foliage that resembles a pine tree, and a Leucospermum 'Tango' with deep orange red flowers. L. conocarpodendron has also done well for me, but is flowering less and less due to too much shade in my garden, the bane of my back yard for the Proteas.

One last plant that undoubtedly should also do well in Oregon would be Nerine bowdenii, one of my favorites in bloom in late October. In talking with several growers in Capetown, this seems to flower more reliably here in California than for them, possibly due to clonal differences or our cooler winter weather.

Psoralea pinnata known locally as Taylorina or Blue Broom is a really invasive weed here in the south of Western Australia, as is Watsonia.