Most species, except for V. labradorica, are listed by Sunset as appropriate for zones 14-24, which would include all of the San Diego area. But these are cool weather plants and struggle or fade in hot weather. Even in more northern, colder climates they are considered cool season plants, blooming often from fall through winter and into spring. If planted at the right time of year (fall and winter in your area), they should bloom well and even set seed, although you will likely not see any seedlings until cold weather returns again in the fall.

Both Viola pedunculata and V. adunca are native to California, although most prevalent along the coast and in the Sierra foothills. Any violet or viola species would appreciate a nicely shaded and properly moist location in CA.

African violets, Saintpaulia, are not violets at all but members of the Gesneriaceae, native to Africa.

There are several species that are more-suited to hot dry summers than what one might think of as 'typical' violets. Some are native to LA-like climates in other parts of the world, but there are some from the US too, such as Viola beckwithii. I suggest you get hold of a copy of this classic work on native US violets, probably through your library (it is a limited edition work; 1,000 copies). The descriptions will tell you which ones would be worth your while trying, and the colour illustrations are rather nice.

Baird, Viola Brainerd. - Wild Violets of North America. Color illustrations by F. Schuyler Mathews, introduction by Herb L. Mason. Berkley and Los Angeles. University of California Press, 1942. x 225 p., 1 l. incl. Illus.(part col) plates (part col.) diagrs. 27 cm.

[more violet refs here - http://americanvioletsociety.org/Books_N_Articles/Literature.htm]

Do be aware, however, that the reason these violets survive in such climates is adaptation - they may disappear below ground during the hot dry months. If you water them to try to prolong their display, they may do as you hope but there is also a risk that they will die.

Mike

Here's some advice I gave to somebody else in California back in 1999, slightly updated.

Hi Sherry,

Thanks for your question (attached).

Although many cultivated violets grow in fairly well-watered and not-too-hot garden situations, there are many species of Viola which naturally inhabit hotter and drier locations. Some of these are native to the USA. Be aware, however, that all or most of those suitable for you in LA will naturally lose their leaves in summer.

V. beckwithii might be worth trying. It is very attractive in flower and its finely dissected foliage, and it is also nicely scented. It naturally grows at highish elevations - up to 6,000ft in the Great Basin, but comes down at least as low as 3,000ft. That's as regards its native range - in the garden it might still do OK. However, the elevation means it gets plenty of water as the snow melts in the spring - and I don't know how wet it might be in LA in spring. It blooms in spring before withering with the summer heat, spending the hottest times of the year resting as a root well below the soil surface. But don't tidy it up too much - each spring it will send up new shoots through the withered remains of the previous season's stems; if you remove the dead leaves and let the soil fill the stem's hole, the soil can 'pan' (harden) and prevent the violet coming through next spring. It naturally grows amongst sagebrush in gravelly soils. The closest to LA you'll find one of these violets in the wild is Inyo County, CA.

Closely related to V.beckwithii are Vv. douglasii (Douglas violet) and trinervata (sagebrush violet). Both of these grow in similar habitats to V.beckwithii and hence would be worth trying. So when trying to find a source for V.beckwithii, ask for these others at the same time. V.douglasii would be worth tracking down since it feels at home in well-drained sunny hillsides and at low altitudes and as far south as San Diego County. It is almost exclusively Californian. V. trinervata is scented like beckwithii, and although it grows in soils which get baked solid in summer, its native range does not extend further south than Oregon, so it might just object to cultivation in LA.

In semi-desert of Utah, Nevada, and California Viola purpurea (pine violet) occurs, and in several forms (a source of much confusion for the botanist). If you can get hold of any form(s) of this, it is worth a try in your LA garden. Despite its name, it is usually yellow flowered.

Saving the best until last... V.pedunculata (California golden violet, Johnny-jump-up) would be worth tracking down since it can make a glorious show on well-drained low sunny hillsides - not perhaps up to the California poppy in dazzle-factor, but nonetheless a lovely spectacle. And it is native to southern California - perfect for you. I understand it is sold as a cut flower by florists, though I have never had the pleasure of seeing it as such. Nor have I seen it in the field. Maybe you could keep an eye open for it on your travels (best March to May): various places southwards from Sonoma County, including the Carmel River Valley near Monterey, and some of the islands offshore southern California. Tell me if you find it.

These violets are not often offered by nurseries, but horticultural societies' seed exchanges might list them; and of course you could try asking in the SweetViolets discussion list if anybody has seed. Also try John Whittlesey. If he can't help with any of the species I have mentioined, I know he has collected Viola seed from a small hot gravelly plateau near Oroville, CA (a long way north of LA, I know). I don't know which species he found there, but whatever they were might do well for you.

What about species from semi-deserts elsewhere in the world ?
V.arborescens comes from near sea-level in the western Mediterranean, often growing in crevices in baking limestone rocks. It is twiggy and has narrow greyish leaves, but the flowers are not very showy. There are several species from Turkey to India might grow for you, but I have little information on them and I expect it would be very difficult to obtain seed. So, on balance, I would suggest sticking with US species.

You can find photos of most of these species at the Calflora project - http://www.calflora.org/cgi-bin/specieslist.cgi?where-genus=Viola.

Here are search results for violets in LA county
- http://www.calflora.org/cgi-bin/specieslist.cgi?countylist=LAX&namesoup=violaceae&plantcomm=any&format=photos&orderby=taxon

From that list, Viola purpurea and pedunculata would be good candidates. You can see their native ranges here
- http://www.calflora.org/cgi-bin/species_query.cgi?where-calrecnum=8309
- http://www.calflora.org/cgi-bin/species_query.cgi?where-calrecnum=8300

Disappointingly, the California Native Plant Society's web site shows only Viola adunca [http://www.cnps.org/]

Last point: I have mentioned seed rather than plants. This is because most of the aridity-tolerant species adapt to their soil as they grow over several years, and can be next to impossible to dig-up (because of fragility of the roots and hardness of the soil) and transplant. And nurserymen would be unlikely to sell plants grown in pots since they would not establish well, methinks.

Hope this helps,
Good luck,
Regards,
Mike
-----Original Message-----
From: SGra361920@aol.com [SMTP:SGra361920@aol.com]
Sent: Friday, April 16, 1999 7:17 AM
To: SweetViolets@onelist.com
Subject: [SweetViolets] Re: Welcome to SweetViolets@onelist.com

From: SGra361920@aol.com

Hi. My name is Sherry and I live in central La. My first questions is can
Sweet Violets be grown in zone 8. We may have been rezoned to Zone 9 due to the heat of the passed few years - I do not know if they have rezoned yet,
but I did hear the zones where no longer accurate. I'm a very stubborn
gardener - I'll give it another try anyway. I planted one last year, but it
disappeared within a few days. I'll try again this fall. Nothing much
survives this summer heat.

Ok, I ordered some more violets and they are doing great in partial shade. I guess all they need in this climate is less sun. I make sure to frequently water them. Or maybe it's just because the dreaded Summer has not come yet. Winter and early Spring here is when all the water comes, the sky is cloudy and the air is moist.

I still can't get violets to grow from seeds, I've tried everything. Soaking them in water and the refrigerator for a month wrapped in a moist paper towel in a plastic bag. Nothing.

Surprisingly they seem to be growing fine in full sun, despite the heat, but I've been making sure they get well watered. They are viola odorata, the wild variety, which I have read several places are much hardier than other violet cultivars.

Well done. I, too, have seen V. odorata doing quite nicely in hot dry situations, though I have also seen them shrivel and die. Growing in hot full sun, they will be at risk from spider mite (often red spider mite). But those pests dislike humidity, so your watering will help deter them a bit. If you get pale speckling on the leaves, suspect spider mites. You'll need good eyesight or a magnifying glass to see them. If you see fine silky webbing, that suggests a significant infestation. Best to be forewarned.
Next issue is to get them to flower, right? Just keep fingers crossed that your cycle of lengthening/shortening days and varying temperature proves suitable - as you can't do much about those aspects.

Mike

Here's a picture of the violets.

They look good. Bear in mind: they produce two types of flower: ones with petals (spring), ones without (summer). Both can give rise to seed capsules, the summer ones more reliably. So even if you don't see flowers this year, you may still find seedpods, and hence you may get self-sown plants.

One of the violets finally put out a single flower. It's in a container under partial shade.

I haven't seen flowers on any of the other violets so far.

(same person in the first post, just a different username)

Well it is a start! V. odorata often starts flowering in autumn, but its main flowering should be in spring. We have to hope that the day length, cooling, etc. convince your plants that spring is spring...

Not a true Violet, but a fine standin, Viola hederaceae, which may still be called the Tasmanian Violet, or have a new proper name, might suit. A splendid little plant, not liking cold Winters.

A replacement I've found that has a fragrance somewhat similar to violets and is more suitable to hotter drier climates in Brown Boronia, native to Australia, although in its native habitat it is said to prefer dappled shade.

(only place I know of where you could get it in the US, the San Francisco botanical garden has it at their plant sales)