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Dormancy Facilitates Survival Through WInter

Deciduous vegetation defoliates for winter dormancy.

Dormancy is not exclusive to vegetation. Many animals are dormant while they hibernate through cold winter weather. Some animals are dormant while they aestivate through hot and dry weather. Fungi and bacteria can maintain dormancy for many years or centuries. Dormancy is a technique for avoiding unpleasant situations, such as cold or hot weather.

Like some animals, fungi and bacteria, some vegetation is dormant through dry weather. This is evident within local chaparral climates and nearby desert climates. Even within a few coastal forests, buckeye defoliates during summer. Such vegetation resumes activity in response to late autumn rain. However, most vegetation here prefers winter dormancy.

Such winter dormancy is especially evident among deciduous species. Many evergreen species merely halt or decelerate their growth, but without defoliation. Several evergreen species defoliate only partially. A few only shed their old foliage as new foliage replaces it during the following spring. Few species prefer to grow most vigorously through winter.

There are a few advantages to defoliation for winter. Wintry wind blows much more freely through defoliated canopies. Evergreen canopies are therefore more vulnerable to wind. In other harsher climates, defoliated canopies do not accumulate much snow. Evergreen canopies might accumulate more snow than they can support. Some get heavy with rain.

Foliage is not as useful through winter as it is through summer anyway. The sun is lower to the south. Consequently, less sunlight gets through more of the atmosphere. Days are shorter while nights are longer. Furthermore, cooling autumn and winter weather inhibits photosynthesis. For deciduous species, foliage becomes less of an asset than a liability.

Dormancy, whether it involves defoliation or not, facilitates a few horticultural techniques. Bare root stock becomes available at the beginning of winter. Transition from its farms to home gardens is much less stressful during dormancy. So is the aggressive pruning that roses and deciduous fruit trees require. Most pollarding is safest during winter dormancy.

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Abutilon

Bloom may become more scarce with cooling weather.

Abutilon X hybridum grows wild from seed within some of our landscapes. Although not prolific enough to be naturalized, dispersion of any viable seed seems odd for hybrids, since most hybrids are sterile. Of course, I do not know for certain if their ancestors were actually Abutilon X hybridum. They could have been other simple species of some sort. Besides, the name seems to apply to any cultivar of unknown parentage, including a few that are not actually hybrids.

Furthermore, even those that are generally sterile hybrids only needed to produce a single viable seed to start the process. Such a seed would likely grow into something that is more genetically stable, and therefore less sterile than its parents. Regardless of their supposed genetic stability, or because of their lack of it, their individual floral color is delightfully variable.

I am no more certain about the common name of this genus, species or group of hybris, which I know simply as flowering maple. Some know it as Chinese lantern. A few may know it as Indian mallow or parlor maple.

I am not so keen on the flowering maple, or whatever it is, for refined landscapes. However, the landscapes here are not so refined, and some are quite rustic. They benefit from the relaxed style, sporadic bloom, and open form of whatever this is.

Bloom is always sporadic, but is a bit more abundant during warm weather. Conversely, it can get scant while the weather is cool through winter. I am impressed by the few flowers that continue to bloom on this particular specimen. So are the hummingbirds. Bloom will likely become more scarce now that the first mild frost occurred last night. Also, foliage may get sparse until warmer weather next spring initiates regeneration to continue the seasonal cycle.

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Frost

Before

This elephant ear was happy and healthy as the sun set last night. As the sun rose this morning, it was sagging from frost damage. The picture that was taken prior to damage posted here (at my previous ‘Six on Saturday’ post) at midnight. Frost likely occurred shortly afterward. The picture that was taken after damage was taken only a few hours later.

Frost does not happen frequently enough to get much consideration here. When it does happen, it is not severe. This particular frost was only thirty- two degrees. Nonetheless, I should have sheltered the elephant ear. It would not have taken much effort to do so. I could have simply moved it over a few feet, so that it would have been under an eave. A few other species were likewise worthy of shelter. A few, though, should not even be grown here. The most practical means with which to avoid frost damage is to refrain from growing species that are vulnerable to it.

Fortunately, the elephant ear and all other species that were slightly damaged by frost early this morning should recover efficiently. Elephant ear typically loses its foliage through winter, and regenerates foliage for spring anyway. No more frost is predicted for the next week.

I am glad that I do not need to contend with the sort of frost that kills vulnerable species completely. The possibility of such weather would be much more limiting.

A pair of bougainvillea that I planted last autumn actually succumbed to frost last winter. Although bougainvillea commonly loses foliage and perhaps a few small stems to frost, basal stems should not have succumbed. I wanted to get them into their landscape during autumn, so that they could benefit from cool rain through winter, and be ready to grow in spring. Their replacements will get planted in spring.

After
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Rainy Weather Begins With Autumn

Weather changes with the changing seasons.

Rain is at least as relevant as temperature is to the seasons here. Temperature does not change as much. The warmest of summer weather does not seem to be terribly hot. Low humidity helps. The coolest of winter weather is not too terribly cold. Some local climates lack frost. The difference between dry weather and rainy weather is much more obvious.

After all, rainy weather ends during spring, and does not resume until about now. Almost no rain occurs during the extensively arid summer season. This includes late spring and early autumn. Summer thundershowers are uncommon. Therefore, almost all rain occurs during winter. Some also occurs somewhat variably during late autumn and early spring.

This is quite normal for local chaparral climates. Comparatively to other climates, it might be both an advantage and a disadvantage. It is why most landscapes, particularly lawns, rely on irrigation. It is also why the growing season is so long here. This climate provides more pleasant weather to facilitate more gardening. It also necessitates more gardening.

Recent rainy weather is likely the beginning of the rainy season. If so, it is obviously also the end of the dry season. Transition from one season to the next is not on a very precise schedule, though. Dry weather could potentially resume for a while. Conversely, El Nino has potential to promote rainy weather. This winter could be even rainier than last winter!

Even if rainy weather does not resume for a while, irrigation requires seasonal reduction. This includes frequency and duration of automatic irrigation. Vegetation consumes much less moisture while dormant through winter. Less moisture evaporates from soil while the weather is cool. Rain may provide most of the garden with more moisture than it can use.

Unfortunately though, rain is also potentially messy. It makes soil muddy, and can cause erosion. It dislodges deteriorating deciduous foliage, especially in conjunction with wind. Colorful deciduous foliage is much less appealing on pavement or lawn than in its trees. Raking fallen leaves, and all other gardening, is less pleasurable during rainy weather of autumn.

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a Tale of Two Jacarandas

Jacaranda seedlings from this year will be ready to grow next year.

Los Angeles is about three hundred and fifty miles to the southeast of Los Gatos. Relative to the number of different climates between here and there, the climates of the two specific locations are surprisingly similar. Nonetheless, they are not completely similar. Winter weather is somewhat milder within the Los Angeles region, with only minimal frost. Some coastal climates there lack frost. Also, spring weather there is a bit warmer than here.

Jacaranda mimosifolia perform spectacularly with such mild winter weather and warm spring weather. Without frost, or even with minimal frost, they can grow taller than thirty feet, and eventually grow broader than tall. After defoliating for the end of winter or beginning of spring, they bloom for late spring, immediately prior to refoliation. Their awesomely vivid blue bloom is almost as profuse as their subsequent foliage. No other tree of comparable size compares to their floral color or floral profusion. That is why jacaranda are so much more popular within the region of Los Angeles.

Here, occasional moderate frost inhibits comparable performance. Trees are generally smaller and more compact, with more globular form. Vigorous growth that develops after frost damage can be structurally deficient, but heavy with lush foliage. Bloom is more sporadic amongst such vigorously vegetative growth. Although very pretty by local standards, jacaranda is not quite as exquisite as it is within the region of Los Angeles.

Nonetheless, I am growing some. A colleague brought me a seed pod from which I extracted seed. Fortunately, only a few more than two dozens seedlings survived a late frost last winter. Otherwise, many more would eventually be in need of homes. A few will likely inhabit our landscapes. A neighbor wants a few. Any extra jacaranda trees can be shared with other neighbors, like so much other surplus.

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Autumn Bloom Is Remarkably Natural

Some bloom adapts to regional climate.

Most flowers bloom during spring. That seems to be most practical. It maximizes the time for their seed to develop prior to the following winter. It conforms to the schedules of their naturally preferred pollinators. Bloom is less likely to succumb to weather through spring. Deviancy is natural though. Many functional flowers quite naturally prefer autumn bloom.

Deviancy, of course, is as complicated as it is natural. Autumn bloom occurs for a variety of reasons among a variety of species. Many can be delightful assets for home gardens. They provide more options for floral color than the most popular of cool season annuals. Some autumn bloom continues as autumn foliar color develops, and perhaps into winter.

Many flowers bloom randomly as warm weather allows them to do so. They may seem to bloom almost continually here. Cool weather may disrupt their bloom only during winter. As weather fluctuates, bloom might resume before a previously disrupted bloom finishes. African daisies provide autumn bloom because autumn is too mild to disrupt their bloom.

Technically, such flowers do not necessarily prefer to bloom during autumn. They merely bloom whenever they can. Most actually bloom most profusely during spring or summer. Canna produces summer and autumn bloom, as it regenerates from its winter dormancy. Otherwise, within frostless tropical climates, it blooms continuously. It is quite adaptable.

Some flowers that are actually more responsive to seasons simply prefer autumn bloom. Joe Pye weed and goldenrod grow only vegetatively through spring and earlier summer. They only begin to bloom about now. Perhaps their seed prefer to grow through cool and damp winter weather. Their seedlings may be vulnerable to desiccating summer warmth.

Naked lady is more extreme. It maintains dormancy through most of summer to bloom as summer ends. Then it grows through winter until spring warmth initiates dormancy again. It seems to believe that it still inhabits its native range within South Africa. Summer there is winter here. Actually, summer weather there is more severe than winter weather there.

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Early Rain

This could be a sequel to ‘Late Summer’ from yesterday. It happened shortly afterward. It certainly adds another interesting component to this already odd year of weather. Although not impossible, rain at this time of year is rare. Almost all of the rain here occurs between late autumn and early spring.

Weirdly, if rain does occur during summer, it typically does so around the fifteenth of August. Seriously, it is very prompt about that schedule. It typically either begins or ends on that same date.

The first flash of lightning of the storm that started the CZU Fire occurred at 11:59 p.m. on the night of the fifteenth of August of 2020, less than a minute prior to midnight. So, although the storm occurred during the early morning of the sixteenth, it technically began on the night of the fifteenth.

This brief rain shower was minimal, but by local standards, it was surprising. I sort of wanted it to continue long enough to dampen and contain the dust of summer. It might have done so briefly, but could not prevent the dust from becoming dusty again shortly afterward. The aroma of damp asphalt dissipated even before that happened. It was fun while it lasted.

Perhaps this rain shower will be the last of this unusually autumnish weather. Warm and dry summery weather typically resumes immediately after brief rain showers that happen during the middle of August. Technically, for a summer rain shower, it is only half a month late. So far, the forecast does not suggest that pattern, but it has been wrong before, even here. I doubt that there will be any more rain prior to autumn, even if cool autumnish weather resumes until then. But of course, I have been wrong more often than weather forecasts.

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Late Summer

Such weather is early this year.

The change of seasons can be boring here. It might seem as if this climate experiences only two seasons. Summer is the primary season, which seems to extend through most of the year, with what seems to be merely a few days of another brief secondary season which is not summer. Perhaps this brief secondary season is autumn, winter and spring, but that is too many letters and big words for such a small season.

That is how those who are familiar with more distinct seasons might perceive seasons of this innately mild climate. Those of us who are familiar with this climate perceive it quite differently. We are aware of the four seasons, regardless of how mundane the transitions between them seem to be. In fact, some might contend that, if autumn seems to be minimal here, it is merely because this climate experiences a fifth season between summer and autumn, which is known as Indian summer.

Indian summer is an extension of summery weather into autumn, and sometimes occurs after summer seems to have begun to succumb to autumn. It does not happen annually, and does not seem to be happening this year, but certainly could. It is sneaky that way.

For now though, autumn seems to be sneaking into the last two weeks of summer, much like Indian summer sometimes sneaks into autumn. Nights have been interestingly cool. Low clouds have been lingering a bit longer after sunrise than they typically do.

However, vegetation that enjoys warmth does not seem to be decelerating for cooler weather. Perhaps such vegetation knows more than the rest of us do about what to expect. Perhaps it is merely more responsive to photoperiod than weather. Regardless, I get the impression that this is how late summer typically is within other climates.

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Humid Weather is Atypical Here

Ferns generally appreciate humidity with warmth.

Aridity is the opposite of humidity. It is why summer warmth is not as unpleasant here as in humid climates. It does not get so much consideration though. Most of the populace of California inhabits arid chaparral or desert climates. Aridity is so typical that any absence gets more attention. Humid warmth is both uncomfortable and relatively uncommon here.

Hurricane Hilary recently demonstrated how unusual humid weather can be here. It was merely a tropical storm as it left Mexico, but was significant nonetheless. Humidity briefly remained elevated after torrential rain in Southern California. It may have lingered longer in regions that lacked rain in Northern California. It caused warmth to seem a bit warmer.

This humidity would have been more horticulturally influential if it had lasted a bit longer. Obviously, irrigation is temporarily unnecessary for saturated landscapes. Some flooded. Some simply absorbed rain. Less obviously, landscapes that received no rain need a bit less water with humidity. Humid weather reduces evaporation from active foliar surfaces.

Humidity also reduces the volatilization of floral fragrance. Fragrant flowers are therefore more fragrant during humid weather. Delicate floral structures also last a bit longer. Many flowers are more turgid and colorful with humidity. All sorts of foliage, particularly tropical foliage and fern foliage, is more lush. After all, most vegetation is from less arid climates.

Humidity influences allergens also, both positively and negatively. Some allergens, such as fungal spores, are more abundant with humid weather. Some allergens, such as dust and pollen, are more abundant with less humidity. That is why humidifiers are helpful for dust or pollen allergies. It is also why dehumidifiers are helpful for fungal spore allergies.

Spontaneous limb failure can be another consequence of humid warmth. It is hazardous because it occurs very unexpectedly without wind. Warmth accelerates vascular activity, which increases foliar weight. Humidity with slow air circulation inhibits evaporation from foliage. If unable to shed enough weight, foliage becomes too heavy for limbs to support.

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Irrigation Technology Can Get Complicated

Modern irrigation does not age well.

Old fashioned irrigation systems were quite thorough, and technically sustainable. They broadcast generous volumes of water over any vegetation that required it. Their systems were too simple to need much adjustment. Their metallic composition was very resilient. That is why so many old systems were in service for so long. Some continue to function.

However, such old fashioned irrigation systems were not perfect. Their consumption was not as sustainable as their plumbing. They wasted water on vegetation that needed less, and pavement. Some of the broadcast water evaporated before reaching any vegetation. Without automation, old irrigation systems operated when convenient for their operators.

Modern irrigation systems are typically more efficient. Automation allows them to operate prior to sunrise to limit evaporation. Most modern systems apply water directly to the soil. This leaves no irrigation water to evaporate from foliar or other surfaces. Also, it prevents evaporation from airborne broadcast irrigation water. Evaporation innately wastes water.

Of course, modern irrigation systems are no more perfect than old systems. Groundcover and lawns still rely on broadcast irrigation. Such systems still waste water on pavement. Automation can actually waste water if not adjusted manually for rain and other weather. Only the most modern automation adapts to weather. No system responds to vegetation.

Consequently, irrigation can become either deficient or excessive as vegetation matures. Many native species need regular irrigation only as they disperse roots after installation. They are likely to rot with the same irrigation as they mature. Many tropical species need more water as they grow. Some vegetation, as it grows, can obstruct broadcast irrigation.

The complexity of modern irrigation systems complicates their maintenance. Automation is merely one component of the infrastructure. Emitters of drip irrigation sometimes need relocation or replacement. They are sometimes difficult to find below healthy vegetation. Because components are plastic, they are not as durable as old fashioned components.