The SF Bay area incorporates four climate zones according to the Sunset Western Garden Book.

Zone 14 is the southern and eastern interior valleys that are fairly cold in the winter and really hot in the summer. This zone certainly isn't conducive to growing "tropicals" because of the winter cold.

Zones 15 and 16 are the "maritime climates" and are marginal, at best, for true "tropicals", although we can grow a lot of "subtropicals" (including the hardier cultivars of Hibiscus rosa-sinensis and Bougainvillea).

Zone 17 is Northern and Central California's "banana belt". Zone 17 is the area IMMEDIATELY around the Bay and IMMEDIATELY on the coast, plus the delta area of Vallejo to Benicia to Pittsburg. This is where "tropicals" grow well (not "perfectly", due to the lack of LOTS OF ACCUMULATED HEAT that some of them need).

So, it depends on exactly where in the Bay Area you live. Your Sunset Western Garden Book will tell you your zone. I'm assuming, though, that maybe you don't have a SWGB. Spelling out "z9" in your title indicates you are still relying on the USDA garden climate system -- not too useful for us California gardeners.

Also keep in mind that almost all tropical plants need plenty of water, hence California gardeners are shying away from them. We go with "Mediterranean" climate plants, many of which "look tropical".

Then again, it all depends on what you define as "tropical plant".

Joe

I am in Sunset Zone 15, I think.

Where do you live? There are many hibiscuses that are actually in the malva family and are very hardy. I can grow the more tropical hibiscus here in Sacramento, with the chance of losing them once every couple of years if not covered. If you are determined, you could keep a plant in a pot, bury the pot in the ground and then bring it in during the winter.
Even the Sunset zones aren't really reliable. Sacramento is classified zone 14, which isn't really the whole story. Depending on where you live. Downtown Sacramento is pretty much a solid zone 10a, except for like once ever 20 years they will get a solid freeze. Where I live, I barely get a frost ever, but 6 miles away, my friend gets a solid freeze almost every winter. These zones are just guidelines.... a good gardener will use her brain.

I live near Pleasanton.

And then there are microclimates, the different areas within a neighborhood or garden. Where I live, for example, we shifted a Bird of Paradise from a more open spot where it never bloomed to a more sheltered spot, next to a south-facing wall, where it reliably blooms. I know gardeners who love to grow semitropicals here, and I have seen huge avocado trees growing in zone 15. Sometimes all it takes is finding the right spot. (But I have also seen gardens that use heating elements in the ground to keep tropicals alive during cold snaps!)

Do you want to grow the Chinese Hibiscus, H. rosa-sinensis? Sunset says it'll grow in zones 12-16. I have seen hibiscus happily growing next to stucco walls and against houses. The reflected heat helps.

More generally, depending on what you want to grow, it may be helpful to find out where the plant is found in its natural range, and create something close to those conditions. Growing tropicals can be more work, since you have to pay attention when the temperatures drop (if you want to keep the plant alive) and coddle them, especially when they are young.

One of the great things about this climate is that nearly anything can grow here. It all depends on how much time and other resources you want to spend. In general, California natives require the least amount of labor and inputs, and tropicals the most.

If it is plumaria you are trying to grow, good luck. I have tried to provide what they like for the last couple of years, and now have one with the pot in the ground in a bed with partial sun. I believe it is not the daytime temperature but the cool 55 degree summertime night temperatures. The 25% daytime relative humidity is also not exactly tropical. Al

Al.... plumies aren't tropical... Hawaii WISHES they were, but they are desert plants.... They originally came from the Mexican desert. I hate to brag, but they bloom for me in Sacramento! :o) but they don't bloom for my friend in Livermore. :o(
I also found more reliable blooming if I stuck them in my greenhouse where it'd get pretty darn hot....

There are many plants in my tropical garden that do well that aren't suppose to....and many that don't do well that should.

It is a hit or miss for me but I like the challenge. My tropical hibiscus came through the winter in perfect condition. Mandevillas...not so much.

The cool night temps and lack of humidity do stunt growth but I have found that many tropical/subtropical plants do well here.

It's been a while since I've posted here, but I feel I have to address a few of the comments made in this thread.

First, I disagree most vehemently with Gardenguru's assertion that "almost all tropical need plenty of water." This comment reflects and perpetuates a misconception by Med garden and native plant enthusisats about many tropicals that is simply not true. While plants such a bananas, cannas, and colocasia require more than the average amounts of water, many tropical plants need much less water than classic Mediterranean garden plants such as roses and citrus. I know the last two aren't truly Med plants, but try finding a classic Mediterranean garden without them.

Just because a plant is called "tropical" doesn't mean it require a lot of water. Not every plant that's designated tropical comes from a high-rainfall area. Some, like plumeria (as Heathen1 points out) are native to dry Mexican deserts. If you dump too much water on them, they WILL rot. There are many other plants, usually from subtropical areas, that perform well with little supplementary water. Palms include the windmill palm, Mediterranean fan palm and pindo palm (Butia capitata).

Bougainvillea is native to Brazilian tropical and sub tropical regions, not a Mediterranean climate. Same can be said for jacarandas. Tropical plants are native to diverse habitats, from dry deserts that get less than 2" of rain a year to rainforest plants. Even plants native to a rainforest don't like a ton of water dumped on them. Think of the undercanopy and forest floor...you have about 100-150' of vines, leaves, branches, insects, epiphytes, animals, and other things before the plants on the floor see a drop of water. What they require is humidity, not a ton of water on the roots.

If you have a solar heated pool, this can provide the humidity that these plants require. If you're closer the the coast, you'll get humidity, but then you lose the heat needed.

To address Butterfly_15's original question, many climate definitions include the SF Bay Area as "subtropical" which is a very lose one. The northern limit is usually lined north of Petaluma. The "rule of thumb" definition is that if you can grow most citrus without protection year round, it's a subtropical area. Livermore is on the far eastern limit of what most climatologists will call "subtropical" which simply defines an area that experience few hard freezes, minimal to no frost.

Hibiscus will actually do better in the Tri Valley Area than along the coast, as will oleander and gardenias because there is more heat.

I hope that helps.

Thanks for all the responses!

Well, I guess my climate definitions are different than others.

The Koeppen-Geiger system defines "Tropical climate" ("A") simply as "hot and wet all year" (although the system does allow for certain areas with "dry seasons" -- these are the "Aw" climates; which do, though, have long periods of lots of rain).

Areas that we call "deserts" are technically called "Arid" climates; they are NOT "tropical" climates despite the heat and plants from these areas are not "tropical" plants despite what some people call them.

No tropical plant requires less water than plants from true "Mediterranean" climates. To call roses and citrus "classic" Mediterranean plants to make a point is an absurd argument. Neither is native to Mediterranean climates. Us "Med" and native enthusiasts do NOT suggest the use of either.

Plumerias are native to tropical areas, including many islands of the Caribbean and the eastern coast of Mexico into Panama. They are not desert plants and do get lots of rainfall. The reason they don't "rot" in their homeland is that (1) they almost always are growing in perfectly drained soil and (2) they never have to sit in COLD wet soil.

By the way, windmill palm is native to temperate China, pindo palm is native to the dry savannah of South America, and the Mediterranean fan palm is, of course, native the the Mediterranean basin, which does, of course, have a Mediterranean climate.

Joe

Joe:

Well, I guess my climate definitions are different than others.

They are...we were talking about subtropical climates, not tropical.

According to the Wikipedia, the following article summarizes subtropical climates:

Subtropical climate is the form of climate found immediately poleward of the zone of tropical climate.

There are various definitions of what characteristics make a climate "subtropical." Climatologist John Griffiths, for example, includes all places with a mean temperature in their coldest month of 6 C (42.8°F) or warmer but colder than 18°C (64.4°F), while in Glenn Trewartha's scheme this climate is defined as having eight or more months with mean temperatures of 10 °C (50 °F) or warmer but with at least one month averaging colder than 18 °C.

Precise conditions vary tremedously within the subtropical climate zone, as it is one of the largest thermal climate zones on Earth. Precipitation traits may be humid, semiarid or arid (some of the world's great deserts fit into the category) and summers may be hot, or merely warm. Most places that have Mediterranean climates (with a pronounced dry season in the summer) are subtropical from a thermal standpoint.

The Koeppen-Geiger system defines "Tropical climate" ("A") simply as "hot and wet all year" (although the system does allow for certain areas with "dry seasons" -- these are the "Aw" climates; which do, though, have long periods of lots of rain).

Areas that we call "deserts" are technically called "Arid" climates; they are NOT "tropical" climates despite the heat and plants from these areas are not "tropical" plants despite what some people call them.

It's not some, but it's most, including people who specialize in tropical horticulture. According to this Koeppen map, there are many arid areas that lie within the tropics (Tropic of Cancer to the Tropic of Capricorn).

Using Koeppen's system to define "Mediterranean" which is a subset of temperate, (as is humid subtropical), the following is from a Texas A&M online syllabus:

C: Mild Mid-latitude - Humid, middle latitude. Land / water differences play a large part. Have warm, dry summers; cool, wet winters. Coldest month average temperature greater than -3°C (27°F) but less than 18°C (64°F).

Found between 30° and 60° North and South, primarily on west and east coasts of continents.

Sub-divided into Mediterranean, Humid subtropical, Marine West coast. Further sub-divided into a, b, or c based on temperature.

Mediterranean (CSa, CSb): Have a distinct dry season due to expansion of sub-tropical high pressure centers in the summer. Mild winters. West coast U.S., Mediterranean, southern Australia, southern Africa.

Humid Subtropical (CFa, CWa): Eastern side of continents. Eastern Texas, southeastern U.S., eastern China, Japan. Located to the west of large semi-permanent anticyclones and warm ocean currents. Winter temperatures lower than Mediterranean climates. Annual range of temperatures greater than mediterranean or west coast climates.

+ Abundant precipitation (30 - 100 inches per year).

Marine West Coast (Cfb, Cfc): Poleward of Mediterranean climates and (generally) along west coasts of continents. Northwest U.S., western Canada, British Isles, France, southeast Africa. Exposure to cold, ocean currents and mid-latitude cyclones. Summer and winters are mild. Low annual temperature range.

Many references also use the term "dry subtropical" and "Mediterranean" interchangably. In one reference, US climatologists prefer to use 0°C instead of -3°C so places like Victoria, BC and Cape Cod don't get lumped in with San Francisco.

No tropical plant requires less water than plants from true "Mediterranean" climates. To call roses and citrus "classic" Mediterranean plants to make a point is an absurd argument.

Please reread my statement without taking it out of context. I said "classic Mediterranean gardens", not the plants themselves. Any argument that says that citrus and roses are not staples of most "Med" style garden design is even more absurd. If you are only speaking the the plants themselves, you are right...I'm discussing classic "Med" gardens as a whole.

Neither is native to Mediterranean climates. Us "Med" and native enthusiasts do NOT suggest the use of either.

Really? You might want to take that up with your friends at Sunset then, since in 2004's Theme Gardens and 1996's Western Landscaping, citrus is prominent mentioned as a primary component of the Mediterranean landscape. Even Heidi Gildemeister's book Mediterranean Gardening brings (and pictures) roses, though ones developed for drought resistance. In addition, there is repeated mention of cannas, camellias, begonias, and other water thirsty plants in all these references and more, though they suggest water-wise management (grouping, close to structures, etc.) to maintain them.

I was making point based on the Mediterranean-styled garden, not "Med" plants in the strictest definition.

Plumerias are native to tropical areas, including many islands of the Caribbean and the eastern coast of Mexico into Panama. They are not desert plants and do get lots of rainfall. The reason they don't "rot" in their homeland is that (1) they almost always are growing in perfectly drained soil and (2) they never have to sit in COLD wet soil.

Yes, there are species of plumeria native to the West Indies, but the plumeria that most are referring to here is (Plumeria rubra), which is native from Mexico to Central America in the dry, Pacific side tropical forests. Parts of these dry areas get little more than 20" of rain per year, which is also typical (since you bring it up) for the dry or leeward side of tropical islands. For example, Guanica (on the southern side of Puerto Rico) gets 15" of rain a year...San Jose almost gets that much and I've never heard anyone say Puerto Rico is not tropical.

By the way, windmill palm is native to temperate China, pindo palm is native to the dry savannah of South America, and the Mediterranean fan palm is, of course, native the the Mediterranean basin, which does, of course, have a Mediterranean climate.

Mediterranean basin have a Med climate, really? Well, avoiding the underlying sarcasm and getting to the original topic, my point was that these palms are native to subtropical regions. But if we use your logic and consider Mediterranean and native plants in the narrowest sense, these palms are out (with the exception of the Mediterranean fan palm of course) because they are not strictly from those regions, even though they are very drought tolerant.

If you want to use the classical climatic definitions, then (uhhhh...by definition) you are right...all tropical areas are wet, humid muggy places that never get below 20°C (68°F). Geographic, horticultural, and everyday layperson's definitions are not as strict. Even using the Koeppen system, plumerias...errrr...Plumeria rubra are native to the arid (B) regions, so which definition do you want to use? You said they were tropical, but using your climate definitions, they are native to "arid." Pick your poison.

You are also saying that "No tropical plant requires less water than plants from true "Mediterranean" climates" while I know that native (and since coastal California is Mediterranean), Med plants such as Platanus racemosa (California sycamore) and Populus fremontii (Western cottonwood) require a great deal of water because they are from riparian (river) habitats. I've seen pygmy date palms (Phoenix robellini) look better than the former with much less water, and that palm is native to Laos.

All of this is just semantics, euphemisms, and opinion. Many of the books, maps and references I've read include the Bay Area as a subtropical area...that was the original question.

Although the posters' title was "SF Bay A Subtropical Area?", the posters' question was "Does anyone know if the San Francisco Bay Area can support tropical plants outdoors?".

Joe

One of my friends lives in Sunnyvale near Fremont Ave. He has a 4' Mango tree in a small half barrel, which he leaves outdoor all year. It is backed to a covered porch and a house wall while facing a south lawn, which must give it the needed humidity and heat. This tree is a pass-along from the previous owner and has been alive for at least 5 years. This year it is starting to bear fruits, the largest ones are almost fist-size now. So with a little planning and luck, you may be surprised at what you can grow here.

I live in Fairfax, Marin Co, in a microclimate which gets a handful of hard frosts in winter. [I wish I could figure out what Sunset zone I'm in--the map in my SWGB is not precise enough for me to figure it out. I think it's 17 but am not sure.]

I'm wanting to plant some plants I think are tropicals: a bananna, some cannas, perhaps a hedychium, and am not sure how they'd do. The planned location would have southwest orientation with afternoon shade. [Cannas did great on a south wall at my house in Sunnyvale, but I'm wondering if the frosts will kill them here in Fairfax. Bouganvilla doesn't make it here.]

Should I expect them to die to the ground & then re-grow in spring?

Karen

Karen,
I think the Cannas will work for you. Frost may kill the tops, but the plants should come back in the spring. Mulch them if you want to be sure. I had them once in an area that gets colder than Fairfax.
Bob

Karen:

A Bob said, cannas will work, though you will have to cut them back in the winter. A nice coat of mulch will assure that the plants will come back as good as new as soon as the weather warms in early spring.

If bougainvillea will not overwinter for you in your garden, then you are most likely in a cold 15 microclimate, as 17 rarely gets a hard frost (as an example , the all time official low at Mission Dolores in San Francisco is 30). You may also want to try one of the hardier bougainvillea varieties such as B. brasiliensis (which is all purple). A general rule of thumb is the lighter the bracts, the more cold sensitive it will be.

Since you've already indicated you get hard frosts, your success with bananas will very much depend on how much heat you get. It is unlikely they'll ever fruit based on your description, but most varieties will overwinter in the ground. A banana needs about 15-18 months of nearly frost-free conditions to produce a hand (fruit). That said, a banana will die back in the winter, but like a canna, will quickly produce new pups. There are some bananas that are hardy in your zone, but most will have to be mail order. Check out a site like Stokes Tropicals or Aloha Tropicals to get a sampling since they have to sell to place that get much colder than yours (but are warmer as a rule, too). Abyssinian bananas, Ensete ventricosum, are ornamental, get big and are short-lived, but they are very hardy and the leaves resist wind shear. There are two...a green form and a red (more burgundy) form.

Hedychium may be a tougher call...they do well in areas with minimal frost, but a hard freeze will knock them back. You might want to try a smaller, but tougher species like H. greenei, in a protected spot (canopy overhead). This one can be found at older or good nurseries such as Berkeley Horticulture and Magic Gardens (where I bought mine a few years back).

The best person to ask goes by Mich_in_Zonal_Denial, as she's a landscape architect based in Marin. She's usually in the Landscape Design or Professionals forum, though when I used to hang here more often, she'd come into this one now and then.

Good luck.

Both Stokes and Aloha tropicals have bad reputations. Ask your local nursery to special order from Monterey Bay Nursery in Watsonville instead. They are a relatively small wholesale nursery with a very strong emphasis on tropical plants that can be grown in Zone 15-17. Check out their excellent banana description under Musa in the following link. They also have a lot of Alocasia, Colocasia, Hedychium, Canna, Tropical Vines, Ferns including tree ferns, and even some borderline palm species under Chamaedorea and Caryota. It is by far my favorite nursery.

I've heard that the heat produced by those little christmas lights is enough to keep a bougainvillea alive during cold snaps. Twine the lights around the main vines in late fall, and when temperatures drop, turn them on for a night or two.

Thanks for the helpful responses.

I don't really want to plant bougainvillea, but was using that as an example to see if it would clarify my zone--and spectre may be right about a z 15 microclimate--dang! I do, however, get strong heat all summer, which may bode well for my experimentation with tropicals. I'm in the base of a sort of mini-valley/canyon, which likely accounts for both the frosts & this heat.

My interest in the banana is mostly for play with foliage form and texture, anyway, and I've had my eye on a red Ensete ventricosum from my research thus far. Thanks for the reminder, daxin, about Monterey Bay. They're one of my faves, too. I'm looking for a colocasia 'Lime Zinger'. Maybe they'll have one.

By the way, when this tropical area is put in, it'll be on drip. Anyone know how much daily water I should give such plants? [Maybe I should ask at tropicals?]

Karen

Hey Karen:

That would depend vary much on the soil composition (I assumes it's adobe clay), how much wind you get, how close together your flora will be (I used word that instead of p***ts so we don't get those annoying underlines), how long you currently run your drip timer for, etc.. All of this will dictate the emitters, bubblers and spacing you will use.

One thing to keep in mind is that tropicals, while they like water, don't like wet feet. Give them a chance to dry before deep watering again. Then leave them alone,

Once this is determined, you're on your way. For guidelines, I used a 2GPH for a 5 gal newly planted banana. As the banana grew, I bumped it up to 3 x 2GPH (very windy, clay, East Bay). If your cannas are in a tight bed, it may be more effiencient to use a 4GPH microsprinkler that you can control the flow radius and spray. It also helps increase the humididty a bit,

I hope that gives you a start!!

love those dueling horticulturists (spectre and gardenguru) - there's a lot of wisdom in between the intellectual slugfests... both of which helped narrow the focus.

both seem to say that there is a lot of wiggle room in gardening, which is good, because, as emerson wrote, "a foolish consistency is the hobgoblin of small minds"

oops:

Looked at your homepage...you're the dude who gave a talk at a San Diego Horticultural Society meeting earlier this year about consistently being inconsistent and dogging purists of every stripe? Sorry I missed it, but everyone raved about it (and still are to this day).

Susi still razzes me with your advice when it comes to mixing in roses and "cottage garden" plants in my garden (I despise 'em). ;-)

spectre

Just to get back to the original poster -- Pleasanton does tend to get some pretty good frosts in the winter, as do Dublin and San Ramon. We are in Walnut Creek near the Diablo foothills with a tiny bit of elevation that catches just enough influence from the Carquinez Strait to our north that we have almost no frost, although downtown WC, in the next valley over, is a bit of a frost pocket. Again, each microclimate is different, and your actual "Zone" may differ from what is in the SUnset Book.

We have great success with subtropicals eventhough we "used to" be classified as Zone 14, then Zone 15. We pretty much never get any morning marine layer (at worst, it is visible off to the west on bad days but always sunny here), and we get a lot of heat, though not as bad as say Sacramento. But our subtropicals are the best producers in our garden. Queen palms, bananas, strawberry guava, pineapple guava, macadamia, sapote, avocado, jacaranda, bird of paradise, philodendron, clivia, bougainvillea, and hibiscus. That being said, we have had a few very light frosts over the bast 4-5 years of having this garden, and the only thing that's had the slightest bit of damage from it is the tropical hibiscus. So that may be a problem for you. Make sure it gets lots of reflected heat and is against a wall. Our double red flowered one is very hardy, but a yellow variety was very fickle. If you have a classic red, it will be better. I have seen some of the other colors around the neighborhood and am always amazed. Our red ones are currently about 6 feet tall and very nice and bushy.

Good luck!

I need mango tree leaves for my new home ceremony. Does anyone(nursery) sell mango plant here in bayarea, i can buy the plant if i have to. But first i need to have mango leaves.

appreciate your help folks!!!

thx

Lodi, where I live, is listed as a zone 14, a climate with some maritime influence, albeit not much. It can get really cold here in the winter. The best way to figure out what can grow in your yard is not to go by the Sunset Book. These are averages and not absolutes. Go to the weather channel and type in your city. Check the extreme highs and lows for your city as well as the averages. We are a zone 9a, according to USDA, yet at one time in January here it got down to 11 degrees, which in reality makes us a zone 8a. So, you have to be careful.

Mamamia,

USDA zones are based on the average annual low winter temperature in a given area, not record lows.

Ryan

Exactly. All time record lows would put everyone a Zone lower than their actual.

Mango trees are available for sale right now, looking really good, at Home Depot in Emeryville. They had two trees last time I looked. They stood right next to the bananas, which were looking sad, but the mangos held up really well in the cold snap.

you're mangos held up? What was you're coldest night there? I'd love a mango, but I think it would be a goner here.

It wasn't MY mango trees - they were Home Depot's in Emeryville. They were uncovered and looked a heck of a lot better than the bananas which were slightly frost nipped and right next to them. Even the Haas avocado had the tenderest little leaves curled but was otherwise fine. Mango wasn't even touched. I was quite surprised it seemed that hardy. Coldest night around there was probably about 30 or 31 though, maybe even 32, not too bad at all. Most of the area got much worse away from the water.

Sometimes I think certain tropicals that are perceived as ultra-sensitive are less sensitive than others that are actually routinely sold. For example, people plant bougainvillea inland where every ten years it might get frost damaged, but some really "tropical" stuff like macadamia or strawberry guava don't even show a scratch. There are so many tropicals that are apparently hardier than we think, at least hardy enough for our very light occasional frosts and the rare freeze evere decade or so.

testing..

The bay area is in no way subtropical-the mildest parts of SouCal barely make that rating. Yet,some subtropical and tropicals do grow here. Plants that never see a chilly day in a human lifetime in habitat, thrive in our long cold wet season-and the occasional freeze.I can't explain it.Something about remnant cold tolerance the botanist say. Some tropicals have it-most dont. The some we can grow. Modifying your climate takes skill and knowledge- and experience. Pleasanton is to me a Sunset zone 14 climate..that is what you should go by..those many 90's are not bay area temps. But with clever use of cover and other protection you can grow many thing that might just sulk in the bay areas cooler weather. But the bay area's frost free areas are nirvana to tropical plant enthusiests like me.Then you can grow exotics under full sun and to full size...at a much slower rate though compared to the true tropics.
If you want full sized,giant, tropicals-move to Hawaii!..but if just the fun of having them grow to a enjoyable size, in fine form,then it can be done!

Until the modified Köppen classification system (along with most physical geography textbooks) drops "Dry Summer Subtropical" as a designation, I'd say the burden of proof is on you Stan.

Ryan

Would a copy of my winter PG&E bill convince more than Koppen who thinks anywhere it does not snow is balmy?.-ha.
If you have lived in the tropics-the bay area is nice.Same for those who have lived in the frigid midwest or such. Mark Twain said it all....
Also socal,i have noticed that when subtropical is used to describe other countrys-those countrys have a solid dominant subtropical native vegetation.What we bring here to grow. California with its hype,can point to one palm species. And few other minor remnant semi tropical desert species.The vast majority of native SouCal tree flora is also native to Oregon,Washington,and east to Colorado. As i said,SouCal barely can make claims to a subtropical climate.
I think we in the bay area can take huge advantage of the lack of 32 temps here most winters(thanks to the moderating bay). But my arthritis tells me it ain't subtropical here.

Hi Karen,
I live in San Anselmo and I have no problem growing cannas. In fact they grow too well and I'm constantly digging them up as they spread like crazy. They do die down in the winter but they always come back. I also grow Hedychium. my only problem with it is that it frequently freezes before the blossoms open. This year I've moved it to a (I hope) better spot. Bougainvillea can grow here too if planted in a warm spot. Check out Andronicos southern wall along Center.

Ruby

Really,Med climate by definition is just a mild temperate climate with summer drought. That's California. And dont forget the short days in winter.
Subtropical? when you get to the middle latitudes of Baja California THEN you are in a real subtropical climate.
And remember, not many native California plants make the transition to the tropics.Our natives are famous for failing in warm humid climates or even the dry tropics. Yet,the subtropical Med flora of South Africa or the Canary Islands seem to thrive in Hawaii or Acapulco.
All the more amazing what modern nurserys and skill can do to give the illusion low elevation California is "tropical" to the rest of the world.

Stan,

Our native flora have few defenses against pathogenic fungi and bacteria that thrive in warm, moist soils. There is no need. With the possible exception of Chile (I need to double check that) we have drier conditions during the warm part of the year than any other Mediterranean climate. It's at least as much a function of warm, moist soil as any other factor.

Another thing to keep in mind is that the flora of both South Africa and the Canary Islands developed in isolation from temperate climate flora. It doesn't have much to do with present climatic conditions.

Discussions like this are why I favor the subtropical / semitropical distinction suggested by someone a while ago.

I might add, what do you think of the subtropical designation afforded to montane tropical forests? You can grow Passiflora parritae with relative ease in the bay area but it is difficult here.

Ryan

Glad you mentioned that Ryan. Some parts of the wetter bay area are dead on mimics of the higher areas of Mexico. Pines,wild agaves and Oaks resemble the montane forests. No surprise the flora of highland Mexico thrive here-with summer water.
But,the possible arctic front every decade or two coupled with the short days of winter-much shorter than wild poinsettias ever endure,are strong distinguishing factors!
And i still say most of the areas of the world called sub/semi tropical are warmer than even SouCal. Parts of South Africa and the Canarys and Australia can support coconut palms and Mango groves(Israel's dead sea area is warmer,milder than SouCal) Mangro groves in SouCal are an experiment-in Israel they are a sure thing as commercial groves.
Southern hemisphere subtropical areas never see below 32 or even high 30's for that matter.They do not have arctic(antarctic, for them of course) intrusions that California into upper Baja Californa get.
The ocean waters and inland freshwaters of SouCal(and for sure norcal) are not of subtropical temps either..never do they stay above 65-70 all year. I dont count heated geiser springs as climate related-Wyoming would be considered subtropical if that counted-ha.Oh,and fully tropical waters are in the 80-95 temps all year by comparison.
I hand it to plant physiology that some tropicals can take for months our winters.
The Today show did a piece on Capetown last week and the Cape of Good Hope. The Cape was 65 and Capetown 15 minutes north by helicopter, was 80f-IN THE DEAD OF WINTER for them. No Santa Ana's to temporarily warm them-those are average dailey winter temps for them.
I really believe it is a hundred years of Hollywood that gets us to think we are in a climate much warmer then the reality. G.W. and urban island effect has raised our mild temperate temps-but still, we are temperate,not subtropical.

Stan,
Don't believe everything you see on television, especially with regard to average winter temps in Capetown and the Cape of Good Hope. They can and do get some frost there occasionally, as they have varied microclimates due to elevation and topography. wind is also much more a factor there, and weather is very inconsistent on a day to day basis as they do get cold fronts off the Antarctic as well as the Atlantic. From my observations of what is growing well in Capetown, I would say the climate is most similar to San Diego in general, but with more winter rains, and 80F is not a typical long term average daily high in winter there. I visited over a 6 week period in the Western Cape in August/September, and the weather was very much like what we get here in the SF Bay Area in mid to late spring. You needed a jacket on many days, there was typically driving windy days alternating with warmer ones, and there was snow on the mountains in back of Capetown above 5000 foot elevation, although it didn't last for more than a week at a time.

Even the subtropical parts of coastal eastern South Africa can also get the occasional frost, and has, so don't believe that it never gets down to freezing along the coast from perhaps Port Elizabeth west to Capetown. As you get to Durban and points east/north, it is distinctly subtropical with no frost, unless you get inland and up into the mountains. Not really safe to generalize about South Africa unless you live there or look up the climate records...

And Capetown does get their local equivalent of Santa Ana winds which result from compressed, heated air descending from the interior mountainous plateau when they get offshore wind conditions. The hot drying winds or the cold onshore winds can be really hard on gardens in Capetown, and large leafed tropicals that need lots of water fair poorly there in such events, and water is costly to provide.

You can certainly grow many tropical plants in the Bay Area. In some areas expect the warm, dry summer air to affect the ones that like humidity. Expect frostbite in many areas to having them froze to the ground in parts of Santa Clara and Contra Costa counties.

Heathen1: I live in Downtown Sacramento. It is a rare year that it doesn't fall below 30ºF (criteria for zone 10a). It is a rare year that I don't have frost-sensitive plants froze (Cupheas, Lantana, etc). The temperatures reported out of Downtown come from one location, two floors high and in between two buildings. I'm four blocks away and it gets much colder here.

I cant speak for every niche of South Africa-but parts of San Diego dropped to the upper 20's and inland San Diego the teens this last winter. That is not my idea of subtropical.One of the worlds mildest temperate climates-sure,And thats my contention. The bay area is also to a lesser degree.
Their are native cacti in Wyoming and Oklahoma. So SouCal is not unique.There are more palms native to South Carolina than SouCal. Being able to grow some of the subtropical flora in your climate doesn't make it a subtropical climate.

Well, it certainly seems that we've had a more subtropical winter this year than last. It got up to 74 a few days ago!

My banana plants are pushing new leaves, and they were never actually killed to the ground by the few frosts we had.

There are areas of Ireland and the UK that can go a winter without frost. Enjoying a mild winter like we have had this year. Maybe we are in a new category between subtropical and mild temperate?..adding it to urban warming of 7.2 million people and the shelter of Home garden structures-Patio's,lattice,walls,rockwork,trees,etc..that help boost the protection to tender plants and it's very possible to have a garden that LOOKS subtropical!

Your right about the banana's..I dont remember a year where almost every large clump of the common banana in the inner bayarea were evergreen. Maybe the drought years?