Cold Winters Have Certain Advantages

Winter frost can improve spring bloom.

Even in May, damage from the frosts of last winter is still evident among some of the more sensitive plants. Lemon trees and bougainvilleas that have not yet been pruned may still display bare stems protruding above fresher new growth. Some bougainvilleas did not survive. Those that are recovering will bloom later because replacement of foliage is their priority for now.

However, peonies, although rare, are blooming better than they have since 1991, right after one of the worst frosts in recorded history. Earlier, some lilacs, forsythias and wisterias likewise bloomed unusually well. While so many plants were succumbing to cold weather, many others were enjoying it.

The reason that peonies typically do not seem as happy locally as they are in severe climates is that they really prefer more cold weather while they are dormant through winter. Without it, they may not go completely dormant, or may not stay dormant long enough to get the rest that they need; and then wake up tired in spring. Cold winter weather promotes more adequate dormancy, which stimulates healthier growth and bloom this time of year. It all makes sense considering that peonies are naturally endemic to colder climates.

A preference for cooler winter weather is also why so many varieties of apples and pears that are grown in other regions do not perform well here. The good news is that as the fruit of local apple and pear trees matures through spring and summer, it may be of better quality that it has been for many years. Trees that typically produce sparsely may produce more abundantly this year. The weather that damaged tropical and subtropical plants was an advantage to others.

Nothing can restore cherries, apricots, peaches and any other early blooming fruit that was dislodged by late rain, but any fruit that survived may be just as unusually good as apples and pears. Not only is the best place for gardening, but minor weather problems can have certain advantages.

Natives Are Right At Home

Some native plants should stay wild.

Long before people came here and imported exotic (non-native) plants from all over the world, native plants had been perfectly happy without any pruning, watering or fertilizing. They had always been perfectly happy with local soils, local climates and even occasional wildfires. Many are still happier in the wild than in seemingly more comfortable refined gardens and landscapes.

It really makes sense though. Most exotic plants need to be watered because they are from climates that naturally get more rain. Some want to be fertilized because they are from regions with different soil types. Some plants prefer cooler winters. Others want more humidity. They crave what they would get in their respective native homelands.

However, plants that are native to California are not necessarily native to here. California is a big place with all sorts of climates and soils. For example, the desert fan palm that is native to warm and dry Palm Springs would not be happy in cool and foggy San Francisco. Big leaf maple that likes the cool winters of the Siskiyous does not like the mild winters near the coast of Los Angeles. The best natives are those that are native to a particular region, or similar region.

Also, there are a few native plants that are not so easy to accommodate in every home garden. Both the giant sequoia, which is the biggest tree in the world, and the coastal redwood, which is the tallest trees in the world, are native to California. Even if the local climate is a good fit, the space available may not be.

One of the most difficult problems for so many natives though, is that they are sensitive to the regular watering that most exotic plants require. The regular watering that lawn needs just to survive is enough to rot the roots of plants that do not expect any water between spring and autumn.

Santa Barbara daisy, penstemon and various salvias are some of the favorite native perennials. Wax myrtle and the various ceanothus and manzanitas are interesting shrubbery. Western redbud and toyon can be big shrubs or small trees. California sycamore and various oaks are big trees for big spaces.

Last Frost Dates Help Scheduling

Frost is unlikely until next autumn.

Frost is not as much of a concern here as it is in other climates. It is very rare in some of the coastal climates of Southern California. The potential for frost damage increases farther inland, farther north, and at higher elevations. Regardless, it is generally tolerable locally. Even if it is necessary to protect a few marginal plants prior to frost, the ‘average last frost date’ gets little consideration.

The average last frost date designates the end of the frost season for a particular region. Although a specific date, it is an average of dates of the last frost of previous years. It includes minor frost that caused no major damage. Damaging frost, although possible, is unlikely afterward. It becomes more unlikely as the season advances. The process reverses after the average first frost date.

Obviously, average last frost dates are as variable as climates. They are irrelevant for climates without frost. Climates with cooler winters generally have average last frost dates later than those of milder climates. For most of us on the West Coast of California, the average last frost date happens before we are aware of it. Nonetheless, it is helpful to know the date for our particular regions.

Warm season vegetable and bedding plants should be safe in the garden after the average last frost date. Directly sown seed should get all the warmth it needs to germinate. Young plants will not likely experience damaging frost. The weather will continue to get warmer. The days will continue to get longer. Cool season vegetable and bedding plants will relinquish their space as necessary.

Plants that sustained damage from earlier frost can now be pruned and groomed. Damaged foliage that remained in place to insulate inner stems is no longer necessary. Pruning and removal of ruined vegetation stimulates new growth while it will be safe from frost. Aggressively pruning and grooming damaged plants that are already regenerating fragile new growth may be complicated.

Most local climates are beyond their respective average last frost dates. Soon, the others will be too.

Winter Is Time For Pruning

Pomegranate trees appreciate major specialized pruning.

Plants are unable to migrate to warmer climates for winter like so many migratory birds do. They are immobile for their entire lives. Only potted plants can move to more sheltered situations when the weather gets too cool for them. Some get to live inside as houseplants. Otherwise, they all must contend with seasonally changing weather. Most are impressively efficient with how they do so.

Most that do not adapt efficiently to cool winter weather are tropical species. Tropicals that are native to high elevations can tolerate cold weather. However, many of the familiar tropical species are from low elevations where they never experience cold weather. Frost damages or kills them. Warm season annuals do not tolerate cool weather either. They just die at the end of their season.

Otherwise, almost all other plants go dormant through winter, at least to some degree. Even evergreen plants, which may not seem to go dormant, grow much slower during winter, or do not grow at all. Deciduous plants are much more obvious about their dormancy, because they defoliate. While bare, they are less susceptible to damage from wintry weather. Dormancy is like hibernation.

This is why winter is the best time for pruning most plants. While dormant, they are less susceptible to distress associated with pruning. Some plants expect some degree of damage from wintery weather during their dormancy anyway. They wake in spring, with no idea of what happened while they slept, and resume normal growth. Winter pruning conforms quite naturally to their life cycles.

There are, of course, a few exceptions. Citrus and avocado should not be pruned during winter. Such pruning stimulates new growth, which is sensitive to frost. Maple and birch should have been pruned earlier. They bleed annoyingly if pruned late into winter. Flowering trees that produce no fruit, such as flowering dogwood and flowering cherry, should be pruned after bloom, late in spring.

Deciduous fruiting trees, such as apricot, cherry, plum, peach, apple and pear, require specialized pruning during winter.

Weather Is All About Climate

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Summer weather continue into autumn here.

Weather has no thermostat. There is no automation. It is naturally variable. Weather is constantly changing like, well . . . the weather. We take what we get when we get it. It is impossible to predict how this summer will end. Others in the Northern Hemisphere are already getting ready for autumn. It is likely to arrive bit later here than elsewhere. That is the nature of the Mediterranean climate.

Summers here are naturally long, dry, and somewhat warm. Rain is rare between spring and autumn. Almost all of the rain happens during the naturally mild winters. Springs and autumns both are naturally quite brief. Such weather may seem to be boring, but is excellent for gardening. It is why the summer growing season is so long. Unfortunately, it is also why the fire season lasts too long.

Indian summer is something of a misnomer here. This is not India. Nor is it Indiana. Besides, Indian summer in other regions of North America describes an unusual weather pattern, not the usual. It is unseasonably warm and dry weather after a first frost of autumn. Alternatively, it is unseasonably early warm and dry weather in spring. Locally, it is merely typical summery weather of autumn.

This weather pattern and climate were assets for agricultural commodities that grew here a long time ago. They are still assets for those who now live here, especially those who enjoy gardening. However, such weather necessitates certain accommodations. Irrigation for actively growing plants is important later into autumn than it is in other climates. Autumn planting happens later as well.

Nights continue to get longer and cooler though. It is not so obvious because gardening happens during the day. Warm season vegetables notice the difference, and slowly decelerate production. Some deciduous plants may slowly begin to discolor. Roses continue to bloom as they slowly begin to shed lower foliage. Eventually, they will get their last applications of fertilizer until next spring.

Warm season annuals may start to to look tired as fresher cool season annuals move in.

Springtime On Time

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According to these maples, spring is right on time.

Seasons in the Santa Clara Valley are not very distinct. They are not much more distinct in the Santa Cruz Mountains above. Hot weather in summer does not last for more than a few days, and usually cools off somewhat at night. Winter is never very cold, with light snow rarely falling only on the tops of the highest peaks.

Some believe that summer is our only season, with a few days of ‘not summer’. I would say that it is more like springtime all the time, with a few warm days, a few cool days, and a few rainy days. In many ways, it is great for gardening. However, it can be limiting for species that prefer more warmth in summer, or a good chill in winter. It can also be rather boring.

The vast orchards that formerly occupied the Santa Clara Valley were fortunately satisfied with the mild climate here, and actually enjoyed it. They got just enough chill and just enough warmth, but just as importantly, they appreciated the aridity. Late rain and humidity can ruin the same sorts of fruits in other climates.

Even without much distinction between seasons, springtime in the Santa Clara Valley was spectacular before the orchards were exterminated. A long time ago, tourists came to see it like the fall color of New England. Many or most tourists witnessed it while the weather where they came from was more like late winter. Natives considered the timing to be right on schedule.

However, the schedule did not coincide with what we learned about seasons in kindergarten. We cut out colored leaves from construction paper in autumn, even though there was not much fall color. We cut out snowflakes from white paper in winter, even though most of us had never seen snow. By the time we started cutting out flowers, most spring bloom was already done.

Norway maples always seemed to know what time of year it was. Schwedler maple, which is a darkly bronzed cultivar of Norway maple, was a common street tree in the Santa Clara Valley back then, particularly in tract neighborhoods that were build in the middle of the 1950s. Some disliked how it stayed bare and seemed to be dead after other trees bloomed and foliated.

To some of us, the reddish new growth of the Schwedler maples was what let us know that it really was springtime. Of course, we were done with all our spring planting by then, as allowed by the local climates. Also, the bloomed out orchards were already foliating. The maples just let us know that winter was completely finished and would not be back for several months.

Five young feral Norway maples at work are doing that splendidly right now. They lack the bolder color of the Schwedler maples, but they make the same statement. The bloom of the flowering cherries is exquisite, but not as convincing as the foliation of the maples.

California Is A Big Place

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There are all kinds of natives.

California is a big place, with more environmental diversity than any other state and most other countries. It includes rainy and cool forests of Del Norte County, and dry and hot deserts of Imperial County. The snowy mountains of Placer County and the mild coastal plains of Los Angeles County are here too. There are hundreds of miles of sandy beaches and big fertile valleys.

Consequently, plants that are native to California are just as diverse. Many that are very well adapted to the environments that they naturally live in are not so well adapted to other environments that may be only a few miles away. They really do not want to go to some of the more divergent climates in other regions.

Coastal redwood that is so happy within its natural range on the foggy western slopes of the coast ranges to the north are not so happy on the drier eastern slopes of the same ranges. It probably would not survive for long in the Mojave Desert. California fan palm from the hot and arid region of Palm Springs languishes on the damp and cool western edge of San Francisco.

Most of the popular California native plants are popular because they do not need much water, if they need any at all. However, some are as unhappy with local climate conditions as exotic plants from other continents are. For example, few plants tolerate drought as well as Joshua tree does. Yet, Joshua tree is likely to grow fast and then rot because winters are too damp for them locally.

Of all the excellent plants that are native to California, the most excellent for local gardens are either the few plants that are native to the local region, or the many others that are native to similar regions. They do not need cold Sierra Nevada Winters, hot Death Valley summers, Mojave Desert aridity or San Francisco fog. They are right at home here.

Even natives need some help adapting to a new garden. Confining their roots to cans while they grow in nurseries is very unnatural for them. Once planted, they will need to be watered while their roots disperse enough to survive on rainfall, or with minimal watering.

Mild Seasons

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These daisies are rarely without some degree of bloom.

There is not as much difference between the seasons here like there is in other climates. It might seem like we get only summer, with a briefly cooler and slightly rainy time of ‘not summer’. I can recognize the changing of the seasons because I am familiar with them. Those acquainted with more normal climate mind find our subdued seasons to be rather boring, and restrictive.

People from climates with more extreme weather and more pronounced seasons might not expect mild weather and mild climate to be restrictive or limiting. They tend to notice what grows here that would not survive out in gardens through colder winters, such as bougainvilleas, tropical hibiscus and so many of the popular succulents. Even more tropicals survive farther south.

What they do not notice are what does not do so well here. Although stone fruit does remarkably well here, and many apples and pears are more than adequately productive, there are many cultivars of apple and pear that prefer more chill than they could get here. Lilac gets sufficient chill to bloom well here, but not enough to bloom as splendidly as it does in the Upper Midwest.

For example, some might be impressed by the perennial daisies that bloom sporadically whenever they want to throughout the year here. These daisies take no time off for winter, and are rarely damaged by frost every few years or so. They are so rarely without bloom that it is not often possible to shear off deteriorating bloom without removing some of the unbloomed buds.

What goes unnoticed is the potentially subdued bloom of the forsythias, which are so reliably prolific where winters are cooler. Some are real duds this year, and all are blooming notably late. This is one of the consequences of a mild climate.

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Forsythia, with twigs that are still bare in the background, is not much to brag about.

Daphne

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Bloom worthy of a Scooby Snack

Jeepers!! As Daphne Blake’s colleague, Fred Jones, might say, “Looks like we’ve got another mystery on our hands.” What got into this Daphne odora ‘Aureomarginata’?! It rarely performs so well here, particularly so soon after being planted into a new landscape. This particular specimen, and about three others nearby, were planted as they finished bloom less than a year ago.

Since their season began, I have been commenting to those who share pictures of theirs, that such healthy and prolifically blooming daphne is enviable to those of us who do not live within a climate that is favorable to such performance. I know that this diminutive floral truss is not exactly exemplary compared to those of other regions, but for this region, it is almost spectacular.

The aroma is exquisite! It is everything that the rest of us grow daphne for, and is enhanced by the delightful but unseasonably clear and warm weather. Surroundings forests dampened by rain almost a month ago maintain just enough humidity for the fragrance to disperse. If it were not such a distinct fragrance, I would be wondering where it is originating. It is so unexpected.

Those in other regions believe that we can grow a more extensive variety of species here where winters are relatively mild. For some, that might be true. However, there are many climactic factors that limit what can be grown in every region. Species that require sustained chill in winter are not very happy here. For daphne, minimal humidity might be what they dislike locally.

Perhaps daphne happens to be happy in the particular location, next to a stream that enhances humidity much of the time when there is not much breeze. Perhaps the weather happened to be be conducive to such a performance. Perhaps it will remain a mystery.