Amazing annuals: The rest of the Cs
We need to move on to other letters so here are a few more annuals beginning with C.

I seem to be stuck with the letter C, like a horticultural Sesame Street on a loop. I was pondering last night as I was brushing my teeth about how inclusive this little series should be and I am torn between mentioning every annual or just a random selection of what I have grown and like. I have decided to go with the latter since I am not writing a book, but there are a few lesser annuals that I do want to mention because they are interesting. And this is not the last C either.
And among these is cladanthus, yet another Mediterranean plant. This is not widely grown but a really nice plant. I like it because of the spreading habit and long-blooming plants though there is just one colour, a rather brassy gold. The flowers are typical daisies but the habit of the plant is rather special. Each stem terminates with a flower ( this is in the Asteraceae so, of course, it is a head of tiny flowers). When the flower opens three to five new stems grow from immediately below it. This is rather like the old hens and chickens daisy and calendula but in those there is a ring of flowers while in cladanthus there are shoots, that end in more flowers, surrounded in shoots and so the plant builds up into a mass of interlocking stems. It is for this reason that the plant is sometimes called criss-cross plant and even the cultivar ‘Criss cross’ which I don’t think is any different from the species C. arabicus.
It is a half-hardy annual, easily raised from seed in spring and I have never had any trouble with it, from a late March sowing. If you don’t mind waiting till July or August for flowers I am sure it would work well grown as a hardy annual, sown in late April or May.
It is also called the Palm Springs daisy but has nothing to do with the place in California but it comes from around the Med (again).

But, moving swiftly on to another C annual, we have clarkia, named for one of the dynamic duo that pioneered their way though the west of North America (1803-6). There are 40 or so species, all but one native to the west of North America and three species are of interest to gardeners. These are Clarkia amoena (above growing wild in Shasta County, California), C. elegans and C. pulchella. Their names give an inkling as to how attractive they are: amoena means delightful, elegans is elegant and pulchella means pretty!
Robinson wrote: ‘These Californian plants of the Evening Primrose and Fuchsia order are among the prettiest of hardy annuals, robust and of easy culture, and flower for a long time.
Clarkia pulchella and C. elegans are what we commonly call clarkia with a tall, willowy habit and, usually, double, frilly flowers up the stems in a wide range of colours including pinks, salmon, purple and white. They can be sown where they are to bloom and both are good for cutting. Each flower has four petals but the commonly sold seeds will produce frilly, double blooms. opening up the stems from the base.

Rather confusingly, Clarkia amoena is the gardeners’ godetia. While clarkias have frilly, ruffled flowers, godetia have larger blooms, usually single or just moderately doubled, but their outstanding feature is the glossy, satin texture of the petals. Breeders have concentrated on making them short and dumpy with large blooms and you will sometimes find godetia plants for sale in pots, ready for brightening the patio, though they will not last more than a month so it is far better to grow from seed. There are some beautiful single colours available while a mix will provide a carpet of shimmering colour in summer.

Various species of Clarkia are native to California, and perhaps to Palm Springs as well.
Despite your recommendations – and their obvious beauty – I am not inclined to take on the work of producing annuals in such numbers.