Every Mediterranean climate has them.  Locals call them the “berg” in South Africa, “brickfielder” in parts of Australia, “harmattan” in Algeria, “levanto” on the Canary Islands, “leste” on the island of Madeira, “leveche” in Spain, “mistral” in southern France and “bentu de soli” in Sardinia.  Collectively they are the “sirocco” throughout the Mediterranean.  East of San Francisco they are “diablo”.

Strong, dry malevolent winds from the interior of the land.  We call them Santa Ana’s and last week we got our first sample of the season.

These dreaded winds – typical of all Mediterranean climates – plague southern California every year, generally from mid-fall through the winter, although they can occur at any time of the year. Scientifically they are the result of cold, high-pressure air masses high over Nevada and Utah. As the air descends to lower altitudes, it warms by compression. However, the air is traveling through the arid great basin and Mojave Desert regions. Thus, by the time it reaches southern California, it is hot and dry. October temperatures over 100°F with relative humidity below 10% are possible.

Fall winds can be strong and constant; funneled through Santa Ana Canyon, the wind’s namesake.  Strong gusts are common. Sometimes, however, the wind seems absent, with only hot, dry air seeping towards the ocean.  Like a slow leak under the kitchen sink, unaware until eventually you look down and it’s all around you.  Sometimes the Santa Ana’s move so slowly that it seems calm. Either way, the extreme low humidity draws water out of plants and soil — and out of our skin.

Gardeners, like others, are restless during these events.  Subtle changes occur, both in our environment as well as our human psyches.  The ocean becomes eerily glossy, the sky takes on a yellow cast and the mornings light quickly, as if a switch had suddenly been turned on.  Animals grow restless and birds may scream at night in the trees.  It’s as if anything can happen.

Once only folklore, there is a documented basis for the effect these winds have on all of us.  Perhaps gardeners, being outdoor types, express these physical and emotional changes more than most.  In southern Spain, the islands of the Mediterranean, Morocco and wherever these hot, dry fall winds blow, doctors are overrun with migraines, nausea and allergies.  Patients speak of “nervousness” and “depression.”   Surgeons are said to watch the wind, because blood does not clot normally.  In schools, some teachers do not attempt to conduct formal classes during a Santa Ana, the children being too unmanageable.  The suicide rate climbs in Europe and some courts consider the winds a mitigating circumstance for crime.

It was during Santa Ana conditions that the Manson murders took their toll, the Watts riots took another toll and the Sylmar, Loma Prieta and Northridge earthquakes took three more tolls.  It is hard for people who have not lived here to realize how radically Santa Ana winds figure in our collective imagination.

A physicist recently explained that these winds carry an unusually high ratio of positive to negative ions.  No one seems to know exactly why that should be; something to do with friction or solar disturbances.  Either way, excess positive ions, in simple terms, make people unhappy.

During these events gardeners unconsciously have the urge to prune; to cut living things.  Pruning shears and saws come out of storage, are suddenly oiled and sharpened.  During these cutting sessions neighboring gardeners periodically meet along property lines, tools in hand.  Lots of ions in the air.  Squabbles erupt over the invasion of tree roots, dandelion seed or the prickly armor of a rambling rose on a fence.  Otherwise docile gardeners may develop subtle ticks and twitches, a haunting expression of the presence of the dry, hot Santa Ana winds.  Spouses beware!

Is it mere coincidence that Halloween falls in the midst of this dry, windy period?  Hmmm.  Spooks, black cats and frightening garden displays; aimed at neighbors.

Last Tuesday in Orange County the humidity was a comfortable 70% and a pleasant 68°.  All was calm in Pleasantville. On Wednesday the Santa Ana’s blew.  The humidity sank to 14% and the thermometer soared to 82°.  Gardeners became anxious.  Ticks and twitches crept into the same muscles that control pruning shears and saws.  Positive ions were out of control.  For many, the desire to prune, to cut something, became insatiable.

Whoa.  This is a gardening column, not a news story.  Not yet anyway.

When the Santa Ana’s do blow, and they will a few more times during the next couple of months, let’s not panic.  You will need to water – abundantly and often.  Misting is good too; just a quick splash around the garden with a hose during the afternoon will cool things down considerably.  The combination of wind, low humidity and high temperature will dry your plants at record speed.  Delicate potted plants, fuchsias and tuberous begonias come to mind, may be better set into protected locations near the house or away from the wind.  Otherwise, hot dry Santa Ana winds are just part of gardening in Orange County, like all other Mediterranean climates of the world.  Try not to get too worked up over it.

Happy Halloween.

Ron Vanderhoff is the Nursery Manager at Roger’s Gardens, Corona del Mar

Ed. Note: The captions of last weeks two photographs were reversed.  The large flower was Matilija Poppy and the berries were Toyon.