Frost Is Just Too Cool

Frost makes tender foliage ugly fast.

Is it too late to warn about frost? After all the rain, the recent and sudden cold weather was quite a surprise. Fortunately, these recent frosts were relatively mild. This sort of weather is probably just enough to start to satisfy plants that require chilling through winter without causing too much damage to too many sensitive plants. So far, only the most sensitive plants, like angels’ trumpet, canna and left-out houseplants show symptoms of frost damage. (Cannas should get cut to the ground at the end of winter anyway.)

Doing without all frost sensitive plants would be too limiting. Lemon, avocado, bougainvillea, fuchsia and Australian tree fern would be off limits. Such plants are worth growing, as long as we understand the potential for occasional frost damage. Those that are too big to protect may sometimes need to get pruned for removal of stems that get killed by frost. In milder climates, such damage will be very rare. In cooler spots, damage is more common, and may involve a few tougher plants, like jacaranda.

Smaller plants that are sensitive to frost, such as jade plant, angel wing begonia and the various pelargoniums, can be grown in containers so that they can be moved to sheltered spots before the weather gets too cold for them. The most sensitive sorts need to be moved under a porch roof or eave, or maybe into a garage. More resilient plants may be safe under overhanging trees or against a wall. South or west facing stucco walls radiate a slight bit of warmth at night.

Frost sensitive plants that get too big for containers should be planted in sheltered spots, like below eaves or larger trees. If a severe frost is predicted, young plants can be protected by burlap, paper, trash bags or any convenient sheeting suspended above by stakes. Foliage that touches the sheeting may get frozen, but foliage within should be fine.

Foliage and stems that get damaged by frost should not necessarily get pruned away immediately. Although unsightly, the dead foliage insulates damaged stems below from subsequent frost. Besides, premature pruning can stimulate new growth, which is more sensitive to subsequent frost.


P00101-1January 1, 2020! The first day of the Twenties!

The flora in our gardens north of the Tropics must think we are crazy for making such a fuss about it while they are trying to sleep. Even flora south of the tropics does not understand. All flora everywhere is more concerned with how the seasons change according to the position of the Earth around the Sun. Precise dates, times and numbers are meaningless.

It sort of seems odd to me that within each time zone, it is the same time and date both north and south of the Equator, but the seasons of each side are opposite. Today started in sparsely populated regions of the Pacific Ocean, worked its way through Australia earlier, and is somehow still the same ‘today’ that is here now. Yet it is winter here, and summer to the south.

Now, if January can be in the cool time of year here, and the warm time of year in Australia, it seems to me that winter could be both the cool season here, and the warm season in Australia. If the dates are the same, it seems like the seasons should be too. Alternatively, if the seasons are half a year early or late in opposite Hemispheres, it seems like dates should be too.

According to such logic, it could be either winter or July 1 in Australia and elsewhere south of the Equator right now! . . . But would that be July 1 of 2019 or 2021? Too many technicalities!

Well, it is more than the flora in the garden is concerned about anyway. It is winter here now, and summer south of the Equator. It is the beginning of January everywhere that the Gregorian calendar is used, north and south.


Note: ‘Horridculture’ will resume next Wednesday. It did not seem appropriate for the first day of 2020.P00101-2

Winter Is For Dormant Pruning

P90316++++The internet makes it possible to communicate with people who enjoy gardening all over the World. It can be amusing to hear what garden enthusiasts in Australia are doing now in early summer. Is it always summer in Ecuador? A common theme in much of America is that there is not much gardening to do right now. It might be more accurate to say that no one wants to go out in the cold.

Where winter weather is too unpleasantly cold to work in the garden, many winter chores can either be done earlier in late autumn, or delayed until early spring. Such scheduling is not a problem, since the plants involved are so deeply dormant through such cold weather anyway. Until the weather warms a bit, they do not want to work in their gardens either. Scheduling is very different here.

Not only does mild weather facilitate gardening chores, but it necessitates the completion of certain chores before the end of winter. Many plants that are mostly dormant while the weather is cool are actually dispersing their roots now that the soil is moistened by winter rain. They will be ready to break dormancy weeks before they would where winters are colder. There is no time for delay.

With a few exceptions, winter is the season for pruning here. Maples and birches should have been pruned earlier, or should be pruned later, so that they do not bleed sap. Citrus get pruned and groomed after the last frost because pruning stimulates new growth that is sensitive to frost. Early blooming flowering crabapples, flowering cherries and forsythias should get pruned after bloom.

Otherwise, most deciduous plants and many evergreen plants should be pruned in winter, while they are as dormant as they get. Pruning now will be less disruptive than it would be while they are more active. They wake up in spring and resume growth as if nothing happened, but relieved of the superfluous growth that was pruned away. Winter pruning is what fits best into their schedules.

Of all plants in the garden, deciduous fruit trees and roses rely on specialized pruning more than most others.

Some Plants Need To Chill

41210thumbIt is easy to snivel about the weather when it gets uncomfortable for us. The rain gets too wet. The temperature gets too cool. Even here on the west coast, without the cold of Minnesota, the heat of Arizona, the humidity of Louisiana or the rain of the west coast of Washington, we tend to think about weather by limited human standards. What we fail to consider is that many other organisms rely on a variety of weather conditions for their survival.

Deciduous plants make it obvious that they know how to deal with cool winter weather. What is not so obvious that that many deciduous plants actually need specific wintry conditions to be convinced that it really is winter. If the weather does not get cool enough, or stay cool long enough, some plants do not go dormant long enough to get the rest that they need in order to perform adequately the following spring and summer.

For example, the reason that only a few of the many different varieties of apple can be grown locally is that most have chill requirements that exceed what they get here. A chill requirement is a specific duration of cool winter weather. Only a minority of all varieties were bred for their minimal chill requirements, so that they will produce reliably even where winters are innately mild.

Besides chill requirements, some seeds like to be soaked in moist soil before they germinate the following spring. This lets them know that it is raining, like it typically does in winter. Pecans, for example, can be soaked for a while inside before sowing, bur really prefer to be out in the garden through winter, where they can tell than rain water is actually flowing past them through the soil, and the microorganisms in the soil help to break down their shells.

It is all about timing. Chill requirements get apple trees to bloom in spring, only after they were convinced that it was already winter. If they were not so specific, they might bloom after a brief cool spell in autumn, leaving their blossoms or developing fruit vulnerable to later frost. Pecans germinate and grow only after the danger of frost, but before the weather gets too dry. If they start too early, they may not survive frost. If they start too late, they may desiccate through summer.

Colorful Autumn And Winter Berries

41126thumbBefore the colorful foliage of autumn falls and gets raked away, a few types of berries and fruit start to provide a bit of color to last into winter, or at least until birds and other wildlife eat them. Technically, the most colorful berries are actually intended for the birds, both those that overwinter and those that migrate south for the winter. The berries are designed by the plants that produce them to both entice birds, and to reward them for dispersing the seeds within.

Pyracantha (or firethorn) is the most colorful of the berries. Cotoneaster is similar, but not quite so prolific. Toyon and English hawthorn, which can grow as small trees, produce open clusters of similar bright red berries. Of these, only English hawthorn is deciduous, and can defoliate before the berries disappear. Although such fruit is abundant, it is not often messy because it gets devoured before it reaches the ground. However, the birds can be messy.

English holly really should produce more berries than it does, but there are not enough pollinators out there. (Hollies are dioecious, which means that plants are either male or female. Female plants need male pollinators to produce fruit.) Decades ago, when horticulture was taken more seriously, male pollinator plants were marketed with female plants. Some other types of holly somehow make a few more berries, especially as they get older.

Loquat, mahonia, pomegranate and some flowering crabapples try to produce colorful fruit, but are not quite as colorful. Pomegranate fruit can be impressive in its own way, but are just rusty reddish brown on the outside. Strawberry tree produces a few red berries throughout most of the year. Many types of pittosporum develop fruit, but most are about as green as their foliage. The sticky amber seeds are ‘interesting’ when the fruit splits open, if anyone happens to look that closely.

Oranges, lemons, grapefruits, mandarins and other citrus will be colorful later in winter, even though they do not care if they attract any birds. For now, persimmons are the biggest and most colorful fruits out in the garden.

Six on Saturday: Above and Below


All that rain was excellent! Now it is cold. There was snow in Malibu in Southern California. It has not been this cold in quite a while. Nonetheless, the weather is grand, and not so cold in the middle of the day. The first three of these six pictures prove it.

1. This was just about sunrise on the first day in a while that did not start with rain. It was cold, and the sky was clear. The trees to the left are Douglas fir. The tree just to the right of center is a ponderosa pine. The tree in the right corner is a coast live oak. This is in one of those spots where different ecosystems collide. The firs merge into redwoods to the left. Ponderosa pines mixed with a few coast live oaks continue to the right, with more pines farther back. All are native.P90223

2. Now it is raining again. I would not say it was real rain, but merely a brief rain shower, with really big and soggy raindrops. Since it lasted only a few minutes, I would still classify this as a sunny day. Unfortunately, the raindrops are not visible in the picture; but the light duty clouds in an otherwise clear sky are. It was sunny when this picture was taken, which means that from some other vantage, this spot was at the end of a rainbow. Those trees are native (coastal) redwoods.P90223+

3. While looking up, I noticed that the exotic (nonnative) sweetgum is mostly defoliated. Rain tends to dislodge the colorful foliage in winter. The two leaning redwood trunks in the middle of the picture are a concern because, although they (and palms) are the most stable trees that I work with, redwoods do not accommodate structural deficiency very well. The asymmetrical distribution of the weight of the trunks above the curves exerts lateral tension on the trunk.P90223++

4. Below all these tall trees, we have a pile of nice madrone firewood that is ready to be split for next year. The native madrone is notorious for instability. Big trees often blow over, or just fall over because they are really bored. The tree that produced all this firewood was cut down because the lower trunk was so very rotten. Yet, as you can see, the firewood from upper limbs is in good condition. Madrone firewood is quite desirable, so this wood is expected to be gone soon.P90223+++

5. The shade under redwood forests is so dark that even these shade tolerant (exotic) gold dust plant want more sunlight. I should have just cut these down, but instead tried to give them a second chance. I pruned out all the dead material, and then pruned out some of the deteriorating stems, hoping that the process would stimulate new grown. That was almost a year ago. Not only has there been no growth or improvement, but the foliage looks even more distressed than it did before!P90223++++

6. Out in a sunnier spot, and after most others have finished, these (exotic) daffodils are still blooming. Actually, they have been blooming for a while. Since there are two different varieties blooming now, I suspect that those that bloomed here earlier were a different variety, or varieties. There is a bit of (exotic) tulip foliage mixed in with them. No bulbs were intentionally planted here on the riverbank, so were likely dumped here in soil that came from a planter or a landscape somewhere.P90223+++++

This is the link for Six on Saturday, for anyone else who would like to participate:

Six on Saturday: After The Storm


Contrary to popular belief, we do get a bit of wintry weather here. It is neither as cold nor as snowy as weather is in most other regions, but it gets sufficiently cool and rainy to let us know it is winter. In fact, here on the western slopes of the Santa Cruz Mountains, we get the little bit of extra weather that does not quite get over the Summit into the Santa Clara Valley. Clouds must unload slightly in order to gain sufficient altitude.

There have been more storms so far this winter than there normally are, and this last week was particularly stormy. It is both a lot of fun, and a lot of work. Storms are innately wet, as well as messy. By the time we catch up from one storm, another arrives. The first few storms are something to be celebrated. The last few start to be rather bothersome.

1. Do you see the well kept shop buildings on the left and right? Neither do I. This is what I found when I got to work on Thursday morning after the electricity was put out by a wicked storm. The lights in the middle are those of a car out on the road. I managed to set up the coffee ‘machine’ to make coffee for the crew when the electricity came back on. I also put the leftover coffee that someone made late the previous night into a pitcher, so that if the electricity did not come back on in time for the crew to make fresh coffee, the first few to arrive could warm up the leftover coffee in the . . . . . . microwave. Okay, perhaps that was not such a good idea. The coffee was just swell cold.P90216

2. Many trees fell during the last few storms. Many more trees lost significant limbs. This unfortunate coast live oak is not as bad as it looks. Once the stub of the fractured limb is removed, it should be just fine. We try to identify potentially hazardous trees, and either work with them to make them less hazardous, or remove them completely. It is nonetheless impossible to predict all hazards. I would have not considered this particular subject to be hazardous prior to the damage seen here.P90216+

3. Artificial poinsettias were removed about a month after Christmas. They are no longer seasonal. Besides, this is the stormy season here, when these artificial poinsettias would be likely to get blown about the neighborhood if left out. If they were to survive the storms, they would fade in sunnier weather of spring. But hey; why must I justify their removal? They are tacky! They will stay hanging in the barn until after next Thanksgiving.P90216++

4. Pruning scraps from zonal geraniums that needed to be pruned back earlier in winter were just too tempting. Rather than discard them, I processed them into cuttings. I tried to give most of them away, but ultimately needed to plug some back into the landscape. They get plugged this time of year so that they get soaked by the rain as they disperse roots. Many went into situations where they will be without automated irrigation. If planted too late, they would just desiccate when the rain stops. These are in a neat row along the base of a stone wall separating a few roses from the roadway, so they will get a bit of water from the roses. So far, they ALL are doing well. Propagation can be such a bad habit.P90216+++

5. This was NOT my idea. I am none too keen on Japanese maples. Yet, this one works very nicely for the particular landscape it is in. I am impressed by the vibrant red color because this particular tree is somewhat sheltered and partly shaded. (Exposure to sunlight and cool wintry weather enhances color.) It looks great among the redwoods.P90216++++

6. No, I do NOT grow ANY of the snowdrops, Galanthus nivalis, or any of the hybrids. ‘Snowflakes’, Leucojum vernum, are only here because they naturalized on the riverbank, likely from seed or bulbs that washed in from a garden upriver. They are spreading quite nicely, and are pleased to bloom in this unirrigated spot after soaked by a few storms. I could have gotten a picture with more flowers in it, but most are already deteriorating. I got these as a closeup instead. I know they are not really snowdrops, but I can brag about them anyway.P90216+++++

This is the link for Six on Saturday, for anyone else who would like to participate:

Finish Transplanting Before Winter Ends

90220thumbAutumn is for planting; and for good reasons. It is the beginning of dormancy for almost all plants, including evergreens. It precedes cool and rainy weather that inhibits desiccation until new roots are able to disperse sufficiently to sustain new plants. Some plants need to be in the garden in time for winter chill in order to initiate bloom. However, not everything should get planted in autumn.

Winter is the best season for some plants. Many summer blooming bulbs get planted in winter because they are likely to start growing prematurely and get damaged by frost if planted in autumn with spring bulbs. Some perennials that are slightly sensitive to frost may get planted after average frost season so that they can bulk up enough to be more resilient to frost by the following winter.

Besides new plants that are purchased from nurseries to be planted in the garden, there are plants that are already established in the garden that might need to get dug, divided, and then planted back into the garden, or shared with friends and neighbors. Some might need to be transplanted because they are crowded or in the way of something. These present a different set of variables.

Once divided and transplanted, grasses, New Zealand flax, lily-of-the-Nile, African iris and other stoloniferous perennials (that spread by creeping stems known as stolons) are more susceptible to rot than nursery grown plants, because so many of their roots get severed. Even if aggressively pruned while getting divided and transplanted, shrubby plants, like lilac and forsythia, are more susceptible to desiccation than nursery grown plants, simply because they lack sufficient roots.

If divided or transplanted through winter rather than autumn, plants get a few weeks of cool and rainy weather to settle and disperse their roots, but do not have enough time to rot or desiccate before the weather gets warm enough for them to resume growth and recover resiliency. Perennials that get cut back in the process spend less time looking shabby before new growth develops.


IMG_8681What is this? It looks more like hail now. It was softer and squishier when it fell out of the sky only an hour or so before this picture was taken. There was a slight bit of snow up on Summit above Los Gatos. It will probably melt as quickly as the clouds clear to let the sunlight through. Snow sometimes appears on the higher peaks around the region, but is rare in lower elevations. Forty three years ago from today, on February 5 in 1976, snow fell in the Santa Clara Valley. It was about half an inch deep in some areas, an inch and a half in others, and was the last snow to fall there.

Bulbs Are Not Finished Yet

90213thumbIt was easy to forget about spring bulbs after they went into the ground so unceremoniously last autumn. They got buried without so much as proper funerals. Cool season annuals got planted over the grave sites of some, just because bare soil is not much to look at. They stayed silent out in the garden through the cool and rainy winter weather. It might have seemed like the perfect crime.

Now they are back. Daffodil, narcissus, crocus and snowdrop might already be blooming. If not, they are at least extending their vertical foliage. Tulip will be right after them. Spring bulbs tend to bloom in very early spring or late winter here, just in time to remind us that there are even more bulbs and bulb like perennials to plant. This is the time of year for planting summer blooming bulbs.

As the name implies, summer blooming bulbs bloom later than spring blooming bulbs. They also get planted later. Unlike spring bulbs, they do not enjoy winter in the garden. (Most spring bulbs are chilled before sale, but would otherwise need winter chill to bloom in spring.) In fact, some summer bulbs are sensitive to frost if they start to grow too early. Types that bloom only once can be planted late to extend bloom, but will need to be watered more carefully after the rain stops.

Dahlia, canna and the old fashioned big white calla are the easiest of summer bulbs. Happy dahlias can last for years, and can be divided if they get big enough. Cannas are even more reliable and more prolific. Big white callas are slow to get started, but can be difficult to contain of once they get established. However, the smaller colorful types are quite demanding, and not so reliable.

Gladiolus and the various lilies are among the most impressive of summer bulbs, but they bloom only once annually, and if not grown in ideal conditions, are unlikely to bloom more than once ever. Lilies want to be watered and fertilized regularly, and grown in rich potting medium. Gladiolus bulbs are typically planted in groups, but only a few in each group will likely regenerate after bloom.