Microclimates Are Different From Climates

Southern exposures are sunny and warm.

Climates are regionally prevalent patterns of weather. The climate here is a chaparral or Mediterranean climate. It is characterized by warm and arid summers, and mild and rainy winters. Many adjacent climates are similar, even if slightly different. Coastal, alpine and desert climates occur elsewhere in California. Microclimates occur within such climates.

The climates of California are as diverse as the geology that influences them. Mountains and valleys and everything in between develops its distinct climate. Some counties here include more climates than some individual states. Many climate zones are impressively compact. So much diversity with small climate zones is often mistaken for microclimates.

Microclimates are small climates within bigger climates. This is obvious. However, there is no definitive description of how small they are. Climates generally conform to geology, like elevation, latitude and proximity of oceans. Microclimates generally conform to what is on such geology, like forests or pavement. They can fit within compact home gardens.

Roofs and pavement of urban areas absorb and radiate significant heat. Such heat alters associated microclimates. Conversely, urban trees and vegetation might cool associated microclimates. Home gardens that are near freeways may be slightly warmer than those that are not. Well forested neighborhoods are a bit cooler during warm summer weather.

These are large scale examples, though. Microclimates originate within individual home gardens also. Southern exposures are much sunnier and warmer or hotter than northern exposures. Eastern exposures are as sunny as western exposures, but are not as warm. Eaves might shelter vulnerable vegetation from mild frost, but also exclude rain moisture.

Microclimates can change as gardens evolve. Shade trees grow to produce more shade. Taller fences may replace shorter fences. Painting a home a different color changes how it reflects or absorbs sunlight. Awareness of microclimates facilitates selection of species for each particular situation. It also facilitates selection of situations for particular species.

Six on Saturday: Cold & Damp

After several weeks of atypically warm and pleasant weather, more typical cool and rainy weather resumed to demonstrate that winter is not quite finished yet.

1. Brugmansia suaveolens, angel’s trumpet becomes rather scrawny through winter as it sheds its larger leaves that grew through summer, and generates smaller leaves instead.

2. Musa acuminata X balbisiana ‘Blue Java’ banana would be notably scrawnier than it already is if more of its discolored and weather damaged foliage were to be pruned away.

3. Viola X wittrockiana, pansy is a cool season or winter annual, but even it craves a bit more warmth than it has been experiencing since it was planted two or three weeks ago.

4. Canna X generalis, canna of various cultivars got cut back as their foliage succumbed to wintery chill and wind, but are already growing fast to replace what was pruned away.

5. Alocasia macrorrhizos, taro was divided just before the weather got cool again, so it is difficult to know if it wilted because of the division, the lack of warmer weather, or both.

6. Philodendron selloum ‘Lickety Split’ split leaf philodendron was divided immediately after the taro, but has not wilted, and seems to be more resilient to the wintery weather.

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/

Six on Saturday: Stormy Weather

Several days of stormy weather were predicted, and came with a flash flood warning and a tornado warning for Christmas, but it really was not that bad. No floods. No tornados.

1. Sandbags were readily available for those who might have needed them for the storms that were expected. The wind was strong, but the rain was not as torrential as predicted.

2. Hedera helix, English ivy and a rotten stump of Lithocarpus densiflorus, tanoak were among the vegetation debris that needed to be removed from roadways after the storms.

3. Pseudotsuga menziesii, Douglas fir contributed to the mess as well. This small bit did not reach the ground, though. Larger branches interrupted electrical service to the area.

4. Cyclamen persicum, florist’s cyclamen looks rather shabby after so much windy, cold and rainy weather without interruption. The weather should be a bit drier for next week.

5. Iris unguicularis, Algerian iris has been more resilient to the weather; and it has been blooming for a long time. This might be its third appearance here in my Six on Saturday.

6. Leucojum vernum, snowflake is what we know as snowdrop. Now that snowdrop is so commonly available online, there could eventually be some confusion with their names.

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/

Frost Protection

For many species, frost damage is not as bad as it looks.

            My colleague in the Los Angeles area still sends me seeds for all sorts of strange plants that I probably should not be growing in my less climactically temperate garden, making it difficult to conform to the primary rule of frost protection: ‘Select plants that are appropriate to the particular climate.’ No matter how often I remind my clients of this rule, I really do not want to abide by it. There are just too many interesting but inappropriate plants.

            So the next option is to grow frost sensitive plants in containers that can be moved to sheltered areas prior to frost. That worked while I had an extra parking space in the carport and some room under the porch for giant bird-of-Paradise, plumeria, philodendrons and such. Eventually though, some of these plants get too large to be contained; and I really do not want to keep pruning them back. Besides, I prefer to grow things in the ground.

            The third option is to put sensitive plants in spots that are naturally warmer, or where they are sheltered below the canopies of large evergreen trees, lath or wide eaves. Just remember that plants under eaves are also sheltered from rain, so may need to be watered occasionally through winter. Steep slopes are not quite as cold because cold air drains off. However, flat areas below slopes get colder as they catch cold air that drains from uphill. South facing exposures are of course warmer than northern exposures.

            I know probably better than most that there are always some plants that are not ‘appropriate to the particular climate’, that I do not want to grow in pots, and that prefer to be out in exposed parts of the garden. For example, bougainvilleas are somewhat tender, have sensitive roots that do not like to be confined, and really want to be out in the open to take advantage of warming sunshine during summer. Such plants in colder areas will either need to be protected, or will get damaged by frost.

            Burlap suspended above the foliage by stakes is typically enough to protect sensitive plants from frost. I have used old towels and linens where my neighbors can not see. Plastic sheeting is also effective, but should be removed before sunlight warms the air too much underneath. Paper grocery bags or cardboard boxes are enough for small plants.

            I actually allow some of my larger plants that would be difficult to cover to get damaged by frost, and then prune out the damage later. If they are too big to cover easily, they are probably big enough to survive frost. Damaged stems should be left until the end of winter both to insulate stems below, and also because early pruning stimulates new growth that is even more sensitive to frost. 

Frost Is Not An Enemy

Among canna, frost damage is harmless.

Rain was one clue. Cooler weather is another. It is now so late into autumn that it will be winter soon. Every regional climate experiences some degree of chill. Some, particularly to the north, experience frost. This limits gardening in two ways. Several species prefer a bit less cool weather. Several prefer a bit more. Every species prefers a particular range.

Apple trees, for example, require vernalization, which is a specific duration of chill. Some cultivars require more than others. Without it, they can not distinguish seasons, so do not know when to bloom for spring. Consequently, few cultivars of apple perform adequately within Los Angeles. However, many perform very well in the cooler climates of San Jose.

Banana trees, conversely, need no chill, and are instead set back by frost. Some tolerate a bit more chill than others; but ultimately, they are all tropical species. They produce fruit only within the months between frosts. Consequently, not many banana trees are notably productive within San Jose. However, they perform better in the climates of Los Angeles.

Banana trees stop growing when the weather is cooler than fifty degrees or so. That is a bit too much chill for them. However, frost does not occur until the weather is cooler than thirty-two degrees. Banana foliage can therefore be safely dormant during chilly weather. That is a range of twenty-two degrees. Different tropical species survive different ranges.

The simplest form of frost protection is to not cultivate species that are vulnerable to frost. This is, of course, a bit too restrictive for many who enjoy gardening. Instead, some grow vulnerable species in pots to move to shelter prior to frost. Some simply grow vulnerable species below the shelter of eaves or big trees. Tenting may also be effective protection.

Alternatively, some species can endure frost damage to recover during warmer weather. If possible, outer foliage that succumbs to frost should remain through winter. It insulates inner growth from subsequent damage. Besides, premature grooming can stimulate new growth that is more vulnerable. Many perennials prefer cutting back after winter anyway.

Trees May Benefit From Winterization

Many trees need no winterization pruning.

Arboriculture becomes more of a concern at this time of year. Although winter is a month away, the weather is becoming increasingly stormy. Wind and rain can dislodge limbs or destabilize entire trees. Some trees may benefit from winterization prior to even stormier weather in the future. Some may need the specialized services of professional arborists.

Dormant pruning of deciduous fruit trees is, incidentally, not the same as winterization. It happens later in winter, after the subjects have been dormant for a while longer. Besides, after proper dormant pruning last year, they should not need winterization now. However, if subjects are defoliated, they should not mind early pruning. They are already dormant.

Ironically, the trees that are more likely to require winterization are evergreen. Deciduous species perform almost all of their own winterization naturally. They defoliate to eliminate most of their resistance to wintry winds. In other words, they become more aerodynamic. Defoliation also eliminates most of the surface area to accumulate heavy water from rain.

Evergreen species are generally more resilient to wind than foliated deciduous species. However, as deciduous species defoliate, evergreen species can not. Evergreen foliage therefore becomes less aerodynamic and more vulnerable to wind. Also, it absorbs more heavy rainwater. The added weight of rainwater causes limbs to sag and perhaps break.

Rain does more than cause foliage to become heavier. It also saturates soils, which can potentially compromise root stability. The timing could not be worse, since wind typically accompanies rain. This is also more of a problem for evergreen species than deciduous species. However, some storms arrive early, and some deciduous species defoliate late.

Winterization pruning is as variable as the trees that benefit from it. Large trees will likely need specialized services that only arborists can provide. Japanese maples may require only minor clipping of stems that have extended too far. Many trees require nothing at all. Ultimately, such techniques should help limbs and trees survive eventual wintry weather.

Rain Will Increase Until Late Winter

The weather is about to change.

Defoliation is the colorful beginning. It indicates that the weather is getting progressively cooler. It then gets messy with the first rain. This is inevitable at this time of year. After all, it is late autumn. Storms will become more frequent as weather simultaneously becomes cooler. So, while gardens are getting wetter, they also take longer to dry between storms.

Ironically, vegetation uses much less moisture while it is so abundant. Deciduous foliage can not perform any evapotranspiration after it defoliates. Evergreen foliage is much less vascularly active while cool. Roots can not utilize all the moisture that autumn and winter rain provides. Soil in some areas might stay moist from now until next spring or summer.

Conversely, summery weather is innately arid and warm. That is how the Mediterranean climate here operates. Moisture is either scarce or abundant. Rain will eventually stop in spring, and then not resume until next autumn. Summer thundershowers are uncommon. Gardening could likely be easier with a bit less rain for winter, and a bit more for summer.

With more rain expected, irrigation needs seasonal adjustment. Such adjustments might need to be incremental, since weather changes incrementally. Manual irrigation might be either less frequent or less voluminous, or both. The same applies to automatic systems, which have a disabling ‘rain’ option. It turns irrigation off without modifying the schedule.

Besides necessitating modification of irrigation, rain can also be messy. It dislodges and accelerates the deterioration of defoliating deciduous foliage. It causes even formerly dry soil to become muddy. A bit too much rain can cause erosion. Cleaning up such mess is less pleasurable while the weather is wet and cool. Then, the weather gets messy again.

Rain can not postpone all gardening. Spring bulbs must get into their garden soil prior to winter chill. Dormant pruning happens later in winter, prior to spring. Fortunately though, gardening is less involved than it is during spring and summer. Maintenance of tools and sorting seed can be indoor tasks for rainy days. So is shopping online for seed, plants or garden tools.

Pollen

For urban areas, the first rain of the season is typically icky. It mixes with all the crud and filth that has accumulated since the last rinsing rain of the previous spring. Damp roads smell like a mix of automotive fluids and wet tires. Asphalt roofs smell like tar. Even urban trees can initially smell like damp dust. It takes a while and a bit of rain for the crud and filth to rinse away.

This is the second rain of the season, and in a less than urban area. It does not smell objectionable, and is not notably cruddy. However, it still flows with an abundance of pollen that had not rinsed away already. Perhaps this pollen accumulated just since the previous rain, although not much has been blooming visibly at this time of year. It is impossible to say even what species dispersed so much pollen. Nonetheless, here it is, floating in the first few puddles to accumulate. Yuck!

It is no wonder that pollen is as effective at pollination as it is. It is impressively abundant and permeating. It is also no wonder that it is such a pervasive problem for those who are allergic to it.

Mild Summer

Weather has been somewhat atypical.

(This article is recycled from a few years ago.)

Now that it is half way through September, it is impossible to ignore that tomatoes did not have a good season. Most of us who grow tomatoes were embarrassed by their performance until we realized that everyone else who grows them was also experiencing similar disappointing results. It was not because we did not water them properly. Nor was it because they lacked particular nutrients. They simply wanted warmer weather.

Plants that were put out early before the warm weather last spring did much better at first, but then decelerated as the weather became milder instead of warmer. Cool nights certainly did not help. Mildew, which typically slows a bit as weather becomes drier (less humid) though summer, instead continued to proliferate so that new foliage became infected almost as soon as it developed.

Earlier predictions that the weather would eventually get warm were not accurate enough for many of us who are only now getting enough tomatoes for fresh use, but not an abundance for canning, drying or freezing. There is still some time for most of the tomatoes that are on the vines now to ripen; but many will probably remain green by autumn. Some but not all of the last green tomatoes can ripen off the vine. Perhaps the only good news about all this is that there should be plenty of green tomatoes for pickling.

Sadly, tomatoes were not the only warm season vegetables to be dissatisfied with the weather. Green bean vines and bushes were generally healthy and made good beans, but did not produce very abundantly. Corn was likewise of adequate quality, but on smaller ears and less abundant. Even zucchini, which typically produces too much, was a bit subdued. Marginal vegetables that really prefer warmth, like eggplant and bell pepper, were downright disappointing.

Even if the weather gets warmer in the last days of summer, languishing tomato plants can not ketchup on production. They can be left to make a few more tomatoes, but will eventually need to get out of the way of cool season vegetables. Cabbage, kale, turnip greens, beets, radishes and all the slower growing vegetables that take their time through autumn, winter and early spring will want their space back soon. They will hopefully have a better season.

If possible, cabbage, broccoli, cauliflower and some of the larger cool season vegetable plants can be plugged in amongst the finishing warm season vegetable plants. Then, by the time the finishing warm season vegetable plants need to be removed, the next phase of cool season vegetable plants is already somewhat rooted and has a head start. This process works well in small spaces with good quality soil.

The main problem with this procedure is that it prevents potentially depleted soil from getting amended and well mixed between planting. It can also be a bit awkward to get the spacing of rows, furrows or mounds of the next phase of vegetable plants to match up with the previous phase. Smaller vegetable plants that get sown directly from seed into rows, like turnip greens, carrots, beets and radishes, really prefer customized bed preparation, after the warm season vegetables have been removed.

Warming Summer Weather

Dog Days!

My great grandfather could remember more summers in Sunnyvale than anyone else. He knew how unique every summer was and continues to be. Some summers are uncomfortably hot from beginning to end. Last summer though, was the coolest in recorded history!

Warm summers are of course best for the fruits and vegetables that like warmth. Peaches, grapes, tomatoes and rhubarb in my great grandfather’s garden always got the best flavor during warm weather. Warm but not too hot weather early in summer made the best ‘Bing’ cherries on my grandmother’s tree in Santa Clara.

Although cool summers are more comfortable for dogs, cats and people, they are not quite as conducive to growing fruits and vegetables. It is still too early to know what this summer will be like, but even though it is now getting warm, the warmth is developing late. The past spring was remarkably mild, with rain lingering later than it typically does.

Consequently, some fruits and vegetables, as well as some flowers and trees, are developing slowly. Peaches may be a bit smaller than they typically are, with slightly milder flavor. Rhubarb should have good flavor because of recent warm weather, but may develop a bit late because it got a late start.

Tomatoes are perhaps expressing the most dissatisfaction with the mild weather. Even tomato plants that were put out in the garden early in spring have grown slowly, and are not nearly as productive as they typically are by the beginning of summer. Some are not yet producing!

Fortunately and unfortunately, the weather has gotten significantly warmer. This may be uncomfortable for us; but is a party for the formerly bored tomato plants. Warmth of course promotes bloom and fruit production, and enhances flavor. If they get what they need, tomato plants that seemed sickly in the past may suddenly grow like weeds.

They should waste no time making up for lost time. Even if mild weather continues into summer like it did last summer, it will still get warmer than it has been. Maturing tomato plants will want more water and fertilizer (if used) as they get larger, and the weather gets warmer.