Posted on by tonytomeo

Nurseries Sell Some Marginal Species.

Heliotrope is available from nurseries in climates that get too frosty for it.

            Limiting selection of plants to those that are appropriate to the local climate is not as easy as it seems. Even in mild climates, plants that should be grown in even milder climates are just too tempting, and have sneaky ways of getting from nurseries into the garden. Consequently, when the weather gets cold, at least a few plants get damaged by frost.

            Geraniums, angel’s trumpet, daisies and many other perennials that are so reliable throughout the rest of the year were likely damaged when the weather recently got harshly cold so suddenly after being so mild. Sensitive plants that got some protection prior to the frost may have avoided damage this time, but will likely need protection again before the end of winter. The only sensitive plants that are reasonably safe are those that are located in sheltered spots or in pots that got moved to shelter.

            Now that the damage has been done, it is important to not rush corrective procedures. Even though frost damaged foliage is unsightly as it deteriorates, it insulates undamaged tissue below. Early removal of the damaged foliage exposes interior stems to frost later in the season. On rare occasion, exposed stems of some plants can be damaged by desiccating cold wind or sun scald. (Sun scald typically happens during summer, while sunlight is most intense.)        

            Early pruning of frost damage can also stimulate premature development of new growth, which is much more sensitive to later frost. Most moderately sensitive plants have no problem recovering from minor frost damage once annually. However, recovery is so stressful and takes so much effort that secondary frost damage to new growth can be much more damaging and even fatal to some plants.

            It is best to delay removal of frost damage until late winter when subsequent frost is unlikely. Large plants that are too unsightly to wait that long should be pruned as minimally as possible, and then pruned as necessary later. Minor distal damage known as ‘tip burn’ of avocado and lemon trees may not need to be pruned out at all if it first gets obscured by new growth that develops after winter.

            This may seem contrary to the importance of pruning most other plants while they are dormant during winter. The difference is that, unlike most plants that stay dormant while the weather is cold, plants that get damaged by frost are not so well adapted to cold winter weather, so do not know that they need to stay dormant until the weather is safe for new growth.      

            Burlap, plastic sheeting or any other coverings used to protect sensitive plants from frost should be removed when it is not needed. These protective coverings hold warmth within, which can stimulate premature development of sensitive new growth. Opaque materials shade the plants below and can eventually cause etiolation (stretching of the stems), which likewise makes plants even more susceptible to frost damage.

Posted on by tonytomeo · 5 Comments

Frosty Weather Can Limit Gardening

Foliar frost damage can be unsightly.

Even here, climate is not perfect. It may sometimes seem to be too warm during summer. However, it might not be consistently warm and humid enough for some tropical species. Winter chill may be inadequate to vernalize some species or certain cultivars of species. However, recently frosty weather has already damaged some vegetation in some areas.

Frost limits what performs well in home gardens in two extremes. Some species prefer a bit more than they experience here. Others prefer less. For example, peony prefers more, while vanilla orchid prefers none. Peony is only marginal where weather is exceptionally frosty by local standards. Vanilla orchid can be offended by minor chill even without frost.

Climates and microclimates limit frost just as frost limits what performs in home gardens. Some coastal climates here only very rarely or perhaps never experience frosty weather. Other climates farther inland or at higher elevations experience frost almost every winter. Within such climates, eaves or canopies of big trees can provide shelter from minor frost.

Vegetation within home gardens should be appropriate to its particular climate. Varieties that are vulnerable to frosty weather are likely safe where frost never occurs. Conversely, they will obviously be susceptible to damage where frost does occur. The best means to avoid such damage is appropriate selection. Climate will not accommodate bad choices.

Gardening could be slightly less interesting without a few bad choices, though. Besides, some of such choices are justifiable with the right perspective. Canna, for example, dies back harmlessly to dormant rhizomes after frosty weather. It wastes no time regenerating as weather warms. Some tropical species may grow in pots to move to shelter from frost.

Tenting can shelter some specimens that are too big to move, or are in the ground. Outer foliage that already succumbed to frosty weather can shelter inner growth. Therefore, if it is not too unsightly, it should remain through winter. Besides, premature pruning is likely to stimulate new growth. Such growth would innately be vulnerable to subsequent frosts.

Posted on by tonytomeo · 2 Comments

Precipitation Should Continue Through Winter

Red sky at morning, meteorological warning.

Deciduous foliage gets colorful with autumn chill. Then, it gets messy. Then, with a bit of precipitation, it gets even messier! It seems like a waste as it all succumbs to rain and, in other climates, snow. It is sensible, though. Deciduous vegetation will be less vulnerable to stormy weather without it. Weather will be getting increasingly stormy through autumn.

This is how the Mediterranean climate here operates. The dry season that begins during spring continues until autumn. The relatively shorter rainy season centers around winter. Therefore, most precipitation occurs during winter. Spring and autumn are brief transition seasons that tend to favor the dry season. Almost no precipitation occurs during summer.

Spring and autumn transitions between rainy and dry seasons are innately variable. The rainy season tends to finish early during spring, but may not. It sometimes pauses before resuming. It may do so more than once. Conversely, the rainy season tends to begin late during autumn, but may begin earlier. Occasionally, precipitation begins disturbingly late.

Generally, the first significant storm with significant precipitation begins the rainy season. This may be difficult to believe with typically significant time between the first few storms. Yet, with cooler weather, elevated humidity, and shorter daylength, moisture lasts longer. Precipitation, even if merely drizzling fog, will likely dampen gardens before they get dry.

Irrigation obviously does not need to be as generous as it was during summer. Until next spring, some vegetation will require none at all. Not only will weather provide and retain more moisture, but vegetation uses much less. Refraining from manual irrigation is easy. Adjustment of automated irrigation systems actually requires more effort and awareness.

As deciduous species defoliate for winter, some other species might get more vivacious. Cacti, agave, and some yuccas that lack irrigation become more turgid with precipitation. Remaining palo verde foliage is likely to become greener and fresher prior to defoliation. Most xeric species utilize moisture from precipitation as it becomes available seasonally.

Posted on by tonytomeo · 13 Comments

Six on Saturday: Red Flag Warning

A Red Flag Warning that began Thursday night continues at least until five this evening. Arid wind severely increases the risk of wildfire during this time. The strong wind can be hazardous, even without fire. Big trees become big problems.

1. Wind developed soon after sunrise yesterday. I tried to get a picture of foliar debris as it fell from the forest canopy, but took only this. Sequoia sempervirens, coastal redwood makes the background, with Quercus agrifolia, coast live oak in the lower left quadrant.

2. Turkeys should hide from such wind. This one was alone and in a hurry, likely to find a sheltered situation with others, and just as likely, after shredding the red berries of the firethorn, Pyracantha coccinea. I saw no others as the wind continued through the day.

3. Sequoia sempervirens, coastal redwood is remarkably stable but structurally deficient where exposed to wind, which is why it grows in dense and mutually sheltering colonies. These big fractured limbs are very heavy, and fell with deadly velocity from very high up.

4. Umbellularia californica, California bay is often destabilized by structural deficiency. In other words, although its trunks and limbs are generally not structurally deficient, rot often compromises the structural integrity of the roots, which then become destabilized.

5. Two California bay trunks that destabilized and blocked the road in the picture above are obscured on the ground by their own foliage here. The fractured trunk that is visible was not structurally deficient, but was pulled down by the other two as they destabilized.

6. Hedychium coccineum X coronarium ‘Peach Delight’ ginger is likely too late to finish blooming. I would like to see it bloom to confirm its identity, but may need to wait until next year. Although irrelevant to the wind, I thought I should feature at least one bloom.

This is the link for Six on Saturday, for anyone else who would like to participate: https://thepropagatorblog.wordpress.com/2017/09/18/six-on-saturday-a-participant-guide/

Posted on by tonytomeo · 12 Comments

Six on Saturday: Fire Season

Fire season can begin as early as May and continue as late as November. It is defined by the rainy season. It is a long season because the rainy season is not. Summer is naturally warm and arid. Native vegetation is consequently desiccated. It is no coincidence. Fire is unfortunately a natural component of the ecosystems here, and native vegetation knows it. Many exotic species also react to the meteorological influences that affect fire season. Some are from similar chaparral ecosystems. However, some are from other ecosystems that are likely less adapted to fire. Perhaps their native ecosystems are less relevant than associated meteorological influences, which is what they are actually reacting to. A forty percent chance of rain on Monday morning is the first chance of rain in a long time.

1. Sequoia sempervirens, coastal redwood is always messy and gets even messier when a breeze dislodges foliage which got desiccated by arid warmth. It is a bad combination.

2. Adiantum capillus–veneris, maidenhair fern also reacted to arid warmth. In the wild, foliar desiccation through summer is normal. It is not so normal in irrigated landscapes.

3. Musa acuminata X balbisiana ‘Blue Java’ banana would enjoy sustained warmth with more humidity. While humidity is inadequate, wind more easily shreds its flimsy foliage.

4. Musa acuminata ‘Kokopo’ or ‘Patupi’ banana is more sheltered from breezes and more generously irrigated, so can exhibit guttation overnight and into the cool early morning.

5. Amaryllis belladonna, naked lady is generating seed as it typically does by now. Seed is very perishable, but grows in soil that is damp from the first rain that ends fire season.

6. Solidago rugosa ‘Fireworks’ goldenrod is only fiery by name. It was a gift from Tangly Cottage Gardening. It is the only bloom I will brag about today, and our first goldenrod!

This is the link for Six on Saturday, for anyone else who would like to participate: https://thepropagatorblog.wordpress.com/2017/09/18/six-on-saturday-a-participant-guide/

Posted on by tonytomeo

Late Summer Heat Confuses Some Vegetation

(This article is recycled from several years ago, so some of its information is irrelevant to current conditions. Also, it posted more than half a day late.)

Weather should but does not always get cooler at this time of year.

After the coolest July in a century, and one of the mildest summers in memory, the recent warm weather at the end of August seemed unseasonable, even though it is actually not unusual for this time of year. Predictions of an Indian summer for this year were made shortly after predictions for this past El Nino winter materialized. The ash blasted into the atmosphere by a volcano in Iceland may have changed all that. No one really knows. The weather continues to change like the weather.

For right now though, the damage caused by the sudden warmth is becoming evident. Fortunately, most of the damage is harmless and should be gone by winter. Some is a bit unsightly. The desiccation of small or potted plants may unfortunately be as serious as it looks. The most severely damaged plants may not recover.

The yellowing inner foliage that eventually turns reddish brown in redwood trees is actually a normal response to foliar desiccation that results from warm or dry weather. As long as the outer foliage remains healthy, this discoloration is harmless. Inner foliage that is more expendable is merely being shed to conserve moisture for the more important outer foliage. This shedding foliage will deteriorate and get cleaned out by wind and rain in autumn.

This older foliage typically sheds naturally throughout summer. However, because the summer was so mild, much of the foliage that should have been shed was not shed. As the weather only recently but suddenly became warm, all the foliage that should have been shed earlier became discolored and began to shed at the same time, which is why it is now so much more noticeable.

A few other trees are also shedding some of their foliage. Trees in areas that are not landscaped or watered may drop dried leaves in even slight breezes. Leaves of deciduous trees that would be colorful and pliable if they fell on schedule in autumn are instead crispy and brown. Maple, oak, ash, sycamore (including plane), willow, poplar, eucalyptus and madrone are among the most affected. Fortunately, this is a harmless response to the warm weather after such a mild summer.

Some Japanese maples are damaged more significantly, but should recover. Because they are naturally understory trees (which prefer to grow in the partial shade and ambient humidity of larger trees), they are not well adapted to warm and dry weather, particularly if it becomes warm as suddenly as it recently did. Some got roasted so quickly that the foliage stays attached to the stems as it shrivels and dries. Foliage that is still partially viable (and hopefully functional) should fall in autumn and winter. Foliage that is necrotic (dead) may linger until it is forced to fall by new foliage that emerges next spring.

Potted plants that were desiccated by the heat may not be so fortunate. Even though they can be unsightly, roasted plants that may be rooted into the ground through their drainage holes should not be moved right away, since the roots that are in the ground are the least damaged and the best hope for recovery. Similarly, roasted plants that hang over the edges of their pots should not be pruned back too severely until later, since exposing the pots to more sunlight will cause more heat to be absorbed if the weather gets warm again.

Posted on by tonytomeo · 4 Comments

Summer Warmth Continues Into Autumn

Dog days of summer are over.

The locally mild climate might be rather boring. Winter weather is not very cold. Summer weather is only sometimes very hot. Then, warmth does not often last for very long. Such climate might seem to be deficient in seasons. Summer seems to be the primary season, with just a few cool weeks of winter. Spring and autumn seem to be only brief transitions.

According to the position of Sirius, the Dog Star, the dog days of summer are done. They are the hottest days of the year for several climates of the Northern Hemisphere. The last was the eleventh of August. The final day of summer is the twenty-second of September. Such dates are less relevant here than elsewhere, though. Warm weather may continue.

Indian summer is more typical here than not. In some other climates, it is unusually warm and dry weather that continues into autumn. In this particular climate, it is not so unusual. Another difference is that it does not occur after earlier frost, as it might elsewhere. Some climates here lack frost anyway. Locally, warm weather is more lingering than fluctuating.

Some vegetation knows how to exploit such weather. Indeterminate tomato varieties can continue to be productive until a first frost. If they started soon after a last frost, they could get sloppy with rampant growth. That should not be a problem if production is the priority. With phasing as late as August, determinate tomato varieties can also produce until frost.

Most popular canna cultivars are hybrids of tropical and montane species. Because they are tropical, they are not accustomed to distinctly cool winter seasons. Because they are montane, they survive mild frost. Therefore, they grow until frost, and then resume growth as soon as they can afterward. Dahlia is similar, but maintains dormancy through winter.

Photoperiod also influences growth. Days gradually shorten through summer regardless of the duration of warmth. Some species are more responsive to this than others. Later in summer, crape myrtle can slowly begin to develop autumn foliar color. It does not require much chill to become strikingly colorful for autumn. It can do so while cannas still bloom and tomato plants still produce fruit.

Posted on by tonytomeo

Planting Should Not Be Complicated

Soil amendment should not be excessive.

Autumn and winter are generally the best seasons for planting. Most vegetation is either less active than during other seasons, or dormant. It is therefore more complaisant to the distress of planting procedures. Weather is cooler and wetter than during other seasons. It is therefore less stressful to vulnerable vegetation recovering from planting procedures.

Nonetheless, planting continues throughout the year. Seasonal vegetables and annuals are seasonal at various times. Planting after any lingering chill or potential frost of winter is safer for several species. Also, planting commonly happens whenever it is convenient for whomever does it. Many species are most tempting whenever they happen to bloom.

Generally, this is no problem. Planting while vegetation is active during warm weather is riskier but feasible. It should preferably happen after the warmest time of day. Weather is likely cooler after three in the afternoon. Unusually hot weather justifies delay for another day. Once planted, thorough soaking settles comforting wet soil around vulnerable roots.

Realistically, most planting techniques and concerns are the same regardless of season. The processes only have more potential to be more stressful now than during dormancy. A few species are actually dormant during summer or even spring. Several spring bulbs, such as narcissi, are now ready for division or relocation. Bearded iris rhizomes are also.

Soil amendment helps new plants to feel more comfortable within their new situations. It encourages them to extend roots from their original media into surrounding soil. It should not be excessive though. Contrary to overly popular belief, it is unnecessary below roots. New plants can sink detrimentally below grade if amendment or loose soil below settles.

Stakes for trees that need them must extend past roots and into solid soil below. Binding nursery stakes should be loosened or removed if possible. Binding, which initially keeps trunks straight, can later interfere with trunk development. All new plants need systematic watering through dry seasons until they disperse roots. Most appreciate a layer of mulch, to retain moisture and insulate.

Posted on by tonytomeo

Aridity Is Opposite Of Humidity

The sky is bluer with aridity.

Aridity is a measure of humidity. Humidity is a measure of aridity. Although opposite, they are similar. Humidity is the quantity of water vapor that is suspended within the air. Aridity is a deficiency of humidity. They are components of weather that are more likely felt than seen. Although, aridity clarifies the air, which typically causes the sky to seem more blue.

Of all components of weather, only atmospheric pressure is less tangible than aridity. It is measurable with instrumentation, but perceptible to very few. Except for its clarification of the sky, aridity is just as invisible. It is more perceptible, though. Just as humidity inhibits dissipation of heat, aridity promotes it. Therefore, arid heat feels cooler than humid heat.

That is why the West Coast is famous for its delightfully arid weather with sunsets. Even when the weather here is warmer than elsewhere, it may be more comfortable. Although undesirable, smog and smoke from forest fires provide color for clear sunsets. Temperate arid weather is more conducive to gardening. However, some vegetation might disagree.

Fragrant flowers can not disperse their fragrance quite as effectively during arid weather. Nor can aromatic foliage disperse its aroma quite as effectively. A few varieties of colorful foliage and flowers may fade a bit faster with minimal humidity. After all, most vegetation within home gardens is originally from more humid climates. It naturally enjoys humidity.

More importantly, most vegetation needs more water through arid weather. It loses much more moisture from its foliar surfaces at such times. Any breeze, which people might like, exacerbates loss of moisture. Obviously, warmth does also. Automatic irrigation requires appropriate adjustment as weather changes. Manual irrigation may become demanding.

Irrigation is less demanding for species that actually prefer local Mediterranean climates. Many of such species are native. Most are native to other regions with similar climates. A few are native to climates that are more arid, but tolerate a bit of extra moisture. Weather and climate do not adapt to a garden. It is best to cooperate with climate than not.

Posted on by tonytomeo

In The Zone

Climate is regional.

We all know how excellent the local climate is for gardening. As we travel around the area though, we also realize that there is more than one climate. Locally, there are at least three of the standardized ‘Sunset’ garden zones, with several more within only a few miles. There are countless microclimates too.

Elevation, terrain, latitude and the proximity of the ocean or large bodies of water all influence the climate. Even though the Santa Cruz Mountains are not very high, they sometimes get snow on top because higher elevations are a bit cooler. When the Summit and Santa Clara Valley floor are cold in winter, the slopes in between are not quite as cold because cold air drains away downhill. The areas closest to the San Francisco Bay stay much cooler through summer because of the insulating quality of the water. 

More localized variables like forests, lakes, direction of slopes and infrastructure affect microclimates. Older neighborhoods with mature trees are shadier and cooler than newer neighborhoods with smaller trees. The west facing slopes to the east get warmer than the east facing slopes to the west. In Downtown San Jose, tall buildings create cool and shady microclimates to the north; and some reflect enough solar radiation to significantly warm areas to the south and west.

It is important to know what climate zone any particular garden is in to be able to select appropriate plants. Besides that, it is important to know the microclimates within the garden to know where each plant will be happiest. Tropical plants that would be happy in Los Angeles might succumb to even mild local frosts. However, plants that might succumb to frost if too exposed may be safe in sheltered microclimates.

Generally, Campbell, most of San Jose, southern Sunnyvale, northeastern Cupertino, northeastern Los Gatos and Union City are all within Sunset Zone 15. Most of Saratoga, southwestern Los Gatos, southwestern Cupertino and Mission San Jose are in Zone 16. Santa Clara, Alviso, Milpitas, northern Sunnyvale and western Fremont are in Zone 17.

None of these zones are too severe. Because of the marine influence of the San Francisco Bay, Zone 17 can actually be relatively boring and not so great for plants that want winter chill or summer warmth. Zone 16 is very similar to Zone 15, but comprises hillside thermal belts where cold air drains away in winter, and also gets a bit warmer in summer. Above and below Zone 16, Zone 15 gets cool enough for plants that want winter chill, but may not get warm enough in summer for plants that crave heat. The Sunset Western Garden Book not only describes the climate zones in detail, but also specifies what zones every plant is adaptable to.