Posted on by tonytomeo

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
Posted on by tonytomeo · 2 Comments

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.

Posted on by tonytomeo · 5 Comments

Out of Tune Trumpet

Brugmansia X cubensis ‘Charles Grimaldi’

Summer was mild. Vegetation that enjoys warmth grew relatively slowly through much of it. Then, toward late summer, and without increased warmth, some vegetation seemed to accelerate growth unexpectedly. Banana and heliconia pups grew like they should have earlier in summer. Angel’s trumpet cuttings began to get somewhat weedy. Some that did not bloom earlier began to bloom now!

Brugmansia X cubensis ‘Charles Grimaldi’ is likely the most popular angel’s trumpet. It is the most vigorous, and may be the most fragrant. One cutting that survived the unusually cool frost last winter grew from its roots to more than six feet tall since then. Now that it is time for it to decelerate growth, it is blooming! Such performance is impressive, but not in tune with the seasons. It can not continue for long, before disruption by increasingly cool autumn weather. Unusually vigorous growth that continues to bloom unusually late could be unusually vulnerable to frost next winter.

This is not the only angel’s trumpet that is out of tune with its seasons. A similarly mature specimen of an unidentified cultivar with single white flowers is about to bloom also. Two older specimens of other unidentified cultivars are growing about as vigorously, although without bloom. One blooms with double white flowers. The other blooms with single pale orange flowers.

About nine copies of each of both cultivars that bloom with white flowers are growing like weeds in #1 cans, with more than a dozen more small cuttings of the cultivar that blooms with double flowers in cells. Only the original matured specimen that blooms with double white flowers actually inhabits a landscape, and is incidentally about to bloom, but is not here with these in the nursery. More will go to landscapes after winter, where their bloom can be enjoyed.

Posted on by tonytomeo · 21 Comments

Six on Saturday: Frosty Forecast

Frost is not a problem here. The several species here that are not resilient to frost are the problem. The first of my Six actually has no problem with frost, but does have a problem with starting too late to finish prior to frost next winter. The second also has no problem with frost, but does not want to bloom as weather cools into autumn. The other four are from a frostless region of Los Angeles. I neglected to protect them from the earliest frost last winter because I did not expect it. Their recovery was slow through mild spring and summer weather. They are now growing vigorously rather than decelerating for autumn. This increases their vulnerability to frost next winter.

1. Dahlia X pinnata, mixed dinnerplate dahlias are starting to grow, with only a third of their season left. I described the delay last week. Only three of two dozen survived so far.

2. Gardenia jasminoides, gardenia seems to be healthy, and generated a typical number of floral buds, but is now shedding such floral buds, likely in response to cooling nights.

3. Solandra maxima, cup of gold vine was new here when it got frosted last winter, then grew slowly through atypically cool weather last spring, and is now growing like a weed!

4. Platycerium bifurcatum, staghorn fern also waited a bit too long to start growing like this. It could eventually enjoy rain and humidity through winter, but not even mild frost.

5. Heliconia psittacorum, parakeet flower has done well since last winter. I brought nine rhizomes from Los Angeles. They are still a bit too small to survive average frost though.

6. Dichorisandra thyrsiflora, blue ginger is likely even more vulnerable to frost. Most of its cuttings did not survive last winter. I am impressed and pleased with the six that did.

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 · 6 Comments

Vernalization Enhances Bloom And Growth

Unusually wintry weather enhances some bloom.

Some gardens continue to recover from the exceptionally wintry weather of last winter. Frost damaged some plants, and killed a few. Wind damaged trees. Excessive rain caused erosion and saturation. This collectively unpleasant weather inhibited some from maintaining their gardens. Yet, some plants that require vernalization are performing splendidly.

It seems like an odd juxtaposition. Bloom of some plants is so unusually robust amongst remaining weather damage. Some bloom is noticeably late while most is precisely on schedule. It is not so odd to the plants who seem to behave so oddly though. Whether they appreciate vernalization or dislike frost, they respond to the weather.

Vernalization is merely attainment of sufficient chill to convince plants that it is winter. Many plants that are endemic to climates with cooler winters appreciate such reminders. It initiates their dormancy and resets their respective schedules. They know that subsequently warmer weather initiates their growing or seed germination season.

Plants that are endemic to climates with mild winters are less reliant on vernalization. Some of such plants are vulnerable to frost. Canna are tropical plants from mountainous regions that sometimes experience frost. They die back harmlessly if frosted, and remain dormant until safely warmer weather. They react to chill, but do not require it seasonally.

Spring bulbs, forsythia and flowering cherries have already bloomed atypically boldly. Later flowering cherries, as well as purple leaf plum, lilac and wisteria continue to do so. Peonies are likely to bloom better than typical a bit later. They are rare locally because of their reliance on typically unreliable vernalization.

Some cultivars of apple and pear are likewise unreliable within locally mild climates. Those that normally perform well here may perform better this year. After early warmth to initiate bloom, stone fruit bloom can succumb to late frost. Last winter though, frost was continuous enough to delay bloom until after the last frost. Extra vernalization may instead enhance production.

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Winter Weather Lingers Into Spring

Late wintry weather delays early bloom.

Winter was epic! Snow was more abundant than since 1976. Rain was more continuous than since 1982. Frost was colder than since 1990. All of this happened within this same winter! Californians generally appreciate rain and snow, and tolerate typically minor chill. Chaparral and desert climates here rarely get much. However, this weather is excessive!

Furthermore, such excessively cold or wet weather was unconducive to gardening. Most of us wanted to stay inside. Home gardens consequently endured neglect in conjunction with extreme weather. Regardless of the current weather conditions, winter is technically done. Now that it is spring, gardens should begin their systematic processes of recovery.

This may entail more effort for those who enjoy gardening than for the associated plants. Most plants are resilient to harsher winter weather than they endured here recently. That is how they survive other less temperate climates. Some may respond favorably to more thorough than typical grooming. Some might prefer later grooming while they regenerate.

Chill can actually enhance performance of some plants that prefer cooler winter weather. For example, some cultivars of apple are barely satisfied with the more typical local chill. They may perform better this year, after a cooler chill. Flowering cherry, purple leaf plum, lilac, wisteria, and many others may do the same. Stone fruits might be more productive.

Several plants do succumb to frost though. Some that typically die back but then recover may not recover this year. For some, the unusually cold frost was lethal. Others rotted as a result of lingering cool dampness. Kaffir lily that is blooming well now may succumb to rot later. Canna that grew early only to succumb to later frost should recover well though.

Some plants that endured frost and saturation last winter might delay their spring bloom. Roses could bloom better but also later, both as a result of cooler than typical chill. Some early spring bulbs that bloomed when they should suffered for it. Rain and wind knocked them into the mud. Later bulbs might avoid a similar fate by delaying their bloom slightly. Fewer conform to a comparably strict schedule.

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Freeze Damage Necessitates Selective Pruning

Warmth stimulates recovery from freeze damage.

Pruning at the proper time has been a concern all winter. Dormant pruning was timely as soon as defoliation began. It remains timely almost until bloom. Pollarding and coppicing are generally although unnecessarily a bit later within that range. Spring pruning begins soon after bloom. Pruning of freeze damage starts after the last reasonable threat of frost.

Frost is as variable as the many climates here. Generally, it causes more damage farther inland and at higher elevations. Conversely and generally, it causes less damage closer to the coast and at lower elevations. Many southern coastal climates experience no frost. However, frigid air drains downhill. Within any plateau, the frostiest areas are the lowest.

Last frost dates should help with scheduling of pruning or grooming of freeze damage to vulnerable vegetation. The last frost date for a climate is the average date of its last frost. Frost becomes increasingly unlikely afterward. That is the best time to add warm season vegetables and annuals to the garden. It is also when to begin grooming freeze damage.

If not too unsightly, freeze damage lingers until the last frost date for two primary reasons. It shelters vulnerable tissue below, including any new growth that develops prematurely. Also, removal of such damage stimulates new growth that would be even more exposed and innately more vulnerable to frost. However, priorities change soon after the last frost.

Then, it becomes important to groom or prune away freeze damage prior to generation of fresh new growth. For milder climates, it is already timely to do so. It might be a while for less mild climates. Even for frostless climates, this might be a good time to groom growth that is only incidentally shabby. Such grooming gets more complicated with new growth.

Many zonal geraniums are already extending new growth up through shabby old growth. Removal of such old growth or freeze damage without damaging mingling new growth is no simple task. If new growth stretches for sunlight below old growth, it might flop without support from the old growth. It may be more practical to cut all growth back to regenerate. Canna also develop similar complications.

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Frost Damage Makes Its Appearance

Frost damage of canna looks shabby.

Exotic plants are not native. They are from someplace else. Yet, most plants within most home gardens are exotic. Most are capable of tolerating the more extreme climates from which they originated. Some tropical or subtropical plants actually prefer milder climates. After the recent cool weather, some vulnerable plants exhibit symptoms of frost damage.

Vulnerability is relative though. Honeybush and elderberry can be mostly evergreen with minimal chill, or deciduous with more pronounced chill. Both tolerate more chill than they can experience here. What may seem to be frost damage of specimens that are normally evergreen could be a normal deciduous response to slightly abnormally cooler weather.

Frost damage is also relative. Partial defoliation of Mexican lime might happen annually after minor frost, so may not be alarming. However, such seemingly minor damage could involve stems or entire trees. Luxuriant canna foliage that so instantly becomes unsightly after minor frost can be more alarming. However, dormant rhizomes are safe until spring.

The simplest means to avoid frost damage is to not grow plants that are susceptible to it. Obviously, that is quite limiting. Besides, plants that were not susceptible last winter may be susceptible this winter or sometime in the future. Weather is annually variable. Some susceptible plants can grow in pots that are portable enough to relocate to winter shelter.

Small but immobile plants that are vulnerable to frost damage may appreciate temporary shelter during frosty weather. Any sort of sheeting or cardboard suspended by any sort of stakes and strings should be adequate. Ideally, the sheeting should not touch the foliage below. Incandescent Christmas lights under such sheeting radiate a slight bit of warmth. Frost occurs only at nighttime locally.

Frost protection can be unsightly, but it is less unsightly than frost damage. Fortunately, it is temporary during frost. If not too unsightly, most frost damage should remain until after the last frost date. It insulates other vulnerable vegetation within. Furthermore, premature grooming or pruning stimulates new growth that is more vulnerable to subsequent frosts.

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How To Deceive Smart Seeds

Some seeds need help to germinate.

Plants could not proliferate as they do if they were as unintelligent as they seem to be. Actually, much of their activity would be considered quite ingenious if it could be observed in a more ‘human’ perspective. From their exploitation of pollinators to their aggressive tactics for competition with other plants, the behavior of plants is obviously very deliberate and purposeful.

Because they are so reliant on the weather, pollinators and so many other environmental factors, the life cycles of plants are on strict schedules. They must also adapt to diseases and all sorts of other pathogens. Fires and grazing animals are problems for many, but advantages to most.

Most seeds develop during summer and autumn. When they fall to the ground, they need to know to delay germination until spring to avoid frost and the likelihood of getting eaten. Seeds of many plants, particularly those from more severe climates, germinate only after being ‘stratified’ by a specific duration of cold weather. Such seeds need to be artificially stratified by refrigeration in order to germinate any differently from their natural schedule, or where winters are not sufficiently cold.

Many seeds require ‘scarification’ by digestion by animals that naturally eat them, or by the quick heat of a wildfire, to break or soften a hard outer coating that otherwise inhibits germination. Seeds that need to be digested actually rely on animals for distribution. Seed that need heat want to be the first to regenerate after a wildfire, before competing plants recover.

Goldenrain tree, and many maples and pines produce so many seeds that even if less than one percent germinate in the garden, they seem to be prolific. However, for more reliable germination of a majority of seeds, they should be scarified. The seeds of many pines that crave fire can be heated briefly in an already hot oven to simulate fire, just enough to heat the seed coat without roasting the seeds. Some people actually prefer to spread them on a piece of paper, and then burn the paper. Seeds that only need their hard outer coating to be damaged slightly might need only to be sanded lightly on sandpaper. I actually prefer to rub my canna or Heavenly bamboo (nandina) seeds on a brick or bit of sandstone.

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Frosted Foliage Is Ugly Foliage

Frosted foliage can be removed now.

Weather is variable everywhere. Climates and seasons are imprecisely regulating. They merely define predictable ranges of the elements of weather, such as temperature, wind, humidity, precipitation and cloudiness. As unusual as weather sometimes seems to be, it generally conforms. Winter weather is mild here, but sometimes leave vegetation frosted. 

Frost was sneaky this winter, by occurring during nights between pleasantly warm days. All elements of the weather were within ranges that are normal for local climate, but their chronology was deceptive. Frost seemed unlikely after such springlike daytime weather. Some foliage was frosted only because protection from frost seemed to be unnecessary.

Frost is now unlikely for most local climates so late in the season. Only climates that are at significant elevation or significantly inland might still experience frost. Coastal and low elevation climates are generally past their last frost dates. Some climates experience no frost at all. Except for within the coolest situations, no more vegetation should be frosted.

Therefore, it is generally safe to prune and groom away unsightly frosted vegetation. It is no longer helpful to insulate undamaged vegetation below. Any new growth that pruning of this nature may stimulate or expose should be safe from frost. Within climates that lack frost, vegetation that gets shabby from chill might also appreciate pruning and grooming.

Pruning and grooming of frosted vegetation can be challenging. Many frosted plants are already actively growing in response to warmer weather. Their new growth mingles with their damaged growth that must be removed. Efficient separation of the two requires a bit of effort and persistence. Fresh and tender new growth is innately vulnerable to damage. 

For example, small new shoots of angel’s trumpet break away very easily if bulky frosted stems fall onto or through them in the process of removal. New shoots of several types of canna emerge from the soil among old shoots while it is too early to cut the old shoots to the ground. Grooming is easier where it can happen earlier, or for cannas that grow later.