Streets Might Benefit From Shade

Proportion is important for street trees.

Shade has become less of a priority for modern urban gardens than it still is for older and more spacious suburban gardens. Significantly less sunlight reaches the ground of such confined gardens among taller and shadier homes and fences. Even where shade might be desirable, space for shade trees might be minimal. Streets are the primary exception.

Streets, and associated curbs and sidewalks, are generally the sunniest situations within modern urban neighborhoods. They collect and radiate ambient heat that warms nearby homes and gardens, even if the weather is already unpleasantly warm. Cars that park on pavement without shade are vulnerable to the most heat, which accelerates weathering.

It is an unfortunate waste. Sunshine that is useless and undesirable on streets would be useful within gardens. Although sunlight is not transferable from one situation to another, it might be partially abatable with shade. Streets are certainly no place for gardening; but the space above them may have potential to accommodate the canopies of shade trees.

Street trees are simply trees that flank streets and other roadways. Most are shady. A few are merely visually appealing. They may inhabit parkstrips, treewells or gardens that are adjacent to sidewalks. Many municipalities prescribe street trees for most of their streets. Conforming street trees are standard accessories for streets within new residential tracts.

Of course, street trees must be appropriate to their particular applications. They must get tall enough for clearance above the largest of vehicles that use the roadways below. For commercial districts, some must also stay above storefront signs. Contrarily, a few street trees must stay below aerial utilities. Street lamps, high or low, require clearance as well.

Size and form are not the only considerations. Roots of street trees must be complaisant with infrastructure. Mess should be as minimal as practical. The most complaisant street trees might stay too small to attain adequate clearance or provide much shade. The most visually appealing might be too messy. Selection of appropriate street trees necessitates significant research regarding every potential option.

Sudden Limb Failure Jeopardizes Safety

Entire trees can also fall unexpectedly.

Windy weather sometimes breaks limbs from trees, or blows entire trees over. Evergreen trees are innately more susceptible to such damage than deciduous trees are. Wind can blow more easily through deciduous trees while they are bare through winter, when most wind occurs. However, deciduous trees are now more susceptible to sudden limb failure. 

Sudden limb failure, or spontaneous limb failure, is a result of gravity rather than of wind. It is actually more likely without wind, during mild or warm weather, particularly with high humidity. It consequently has potential to be more hazardous than limbs that blow down. More people go outside among trees during mild weather, and fewer expect falling limbs. 

Sudden limb failure occurs if limbs become unable to support their own increasing foliar weight. Warmth accelerates vascular activity, which sustains foliar growth. High humidity and a lack of wind inhibit evapotranspiration (evaporation from foliage), which otherwise helps to alleviate excessive weight. Developing fruit can also cause sudden limb failure.

In the wild, willows, poplars, sycamores, and perhaps a few other riparian trees regularly and naturally exhibit partial sudden limb failure. Limbs that fracture and sag onto soil, but remain partially attached to their original tree, can generate roots and grow as new trees. Although their strategy is practical for them, it is unacceptable within refined landscapes. 

Several native and exotic trees of chaparral climate are quite susceptible to sudden limb failure within or adjacent to irrigated landscapes. Since they are not accustomed to such abundant moisture, they overindulge. Mature wild trees are more likely to exhibit sudden limb failure after an unusually rainy and warm winter, or if rain continued late into spring.

All native oaks, particularly valley oak and coast live oak, are susceptible to sudden limb failure. So are Monterey pine and Monterey cypress. Carob, sweetgum, various elm and various eucalypti are exotic species that are notorious for such behavior. Evergreens are more unpredictable, since their new growth is less obvious among their lingering foliage. 

The Stakes Could Be High

Some unfortunate trees become so reliant on staking and straps that they are never able to support their own weight.

The irony of landscaping and gardening to bring nature closer to the home is that it is so very unnatural. Plant specie are imported from all over the world, grown in synthetic environments, and then expected to perform in unfamiliar climates and soils far from home. Most plants have been bred for optimal retail appeal at the expense of their natural adaptations.

Trees grown in nurseries need to be staked tightly to develop the sort of straight trunks that branch at just the right height to be marketable. In the landscape, trees need to be staked because they have become so dependent on the stakes that they grew up with. Eventually though, trees need to learn how to carry their own weight.

When new trees get planted and staked loosely with heftier stakes that stand up to wind, old tightly bound nursery stakes should be removed since the tight binding interferes with trunk development. By the time trees gets planted, the nursery stakes are probably nearly rotten through at the ground anyway. The new heftier stakes should not hold trees tightly in place, but simply be there to keep them from getting blown over.

Straps should likewise not be tightly bound, but instead allow for a bit of motion with the breeze. Straps should cross over in a ‘figure eight’ pattern between trees and their stakes, so that trunks do not rub so abrasively against the stakes. Most trees need only two straps each, or two pairs of straps if two stakes are used, with support up high, and lower support to prevent outward bowing. If there are no branches to hold straps in place, straps must be nailed or otherwise attached to the stakes.

Some sturdy trees, like well developed redwood trees and small magnolias, may not need stakes. Palms and yucca certainly do not. However, limber trees like the various eucalyptus may need more support than just two straps. The problem is that many trees become dependent on their stakes and will not develop strong trunks if they do not need to.

It is better to prune maturing staked trees to limit weight and wind resistance (that might cause them to blow over) than to provide more support with heftier stakes. If a maturing young tree is relying on stakes and straps for support, it needs to be pruned. A young unstaked tree that begins to lean from the weight of its canopy should likewise be pruned until it regains its posture without getting staked and bound. Trees should never be tied to other trees, buildings or anything else that can be damaged by the tension.

UTILITY CABLES NEED SPACE

With all the cables coming and going, this unfortunate tree does not have much room to grow without causing trouble.

Since I did not make the drive up or down the coast very often, the rare silvery-gray Bismarck palm that I could see slowly climbing into the skyline near the edge of Highway 101 through Santa Barbara seemed to be slightly taller every time I saw it. It grew slowly, but enough to notice since I only saw it less than annually. Then, when I drove by about a month ago, it was gone.

This exemplary specimen had been quite healthy and happy (even though Bismarck palms are not supposed to be happy on the coast). There was only one problem. It was under high voltage utility cables. As it grew, it got too close to the cables, so needed to be removed in order to maintain the minimal clearance required for high voltage.

Unlike other trees, palms have only single terminal buds that grow upward. They can not develop branches to grow around cables, so only die if the single bud needs to be pruned away. Complete removal is therefore the only option when palms begin to grow into high voltage cables.

Sadly, palms often get planted under utility cables. Many Mexican fan palms grow under cables because birds that eat their fruit drop the seed there. Queen palms are popularly planted around the perimeters of back yards, and along the back fence lines that are very often directly below and parallel to high voltage cables.

Trees that are not palms can get disfigured by pruning for clearance around high voltage cables, but generally survive. Trees with central leaders (single trunks) and strict form, such as spruces and redwoods, can get be so disfigured that removal may be more practical than pruning. Trees with more irregular form, like sycamores and elms, are somewhat easier to salvage. Unfortunately, crews hired to maintain clearance are unable to prioritize the health and structure of trees that get too close to high voltage cables.

Lower cables for telephone, television and house-drops (lower voltage cables that extend from utility poles to homes and other buildings) do not often justify pruning for clearance like upper high voltage cables do. However, these lower priority cables can still be damaged if too many limbs sag onto them or become abrasive as they blow in the wind. Really, it is best to avoid problems with utility cables by selecting and planting trees that are not likely to become too obtrusive. Palms, large trees and trees that are likely to be severely disfigured by pruning to maintain clearance should be kept at safe distances.

Late Pruning For Early Bloomers

Deciduous magnolias get pruned after bloom.

Winter is generally the best season for pruning. Obviously, it is when a majority of plants are dormant, and therefore most complaisant to such potentially invasive procedures. Of course, there are exceptions to this generalization. A few plants are dormant during other seasons. Some simply prefer late pruning to accommodate their bloom or fruiting cycles.

Late pruning is important for some of the same reasons that dormant or winter pruning is important. It controls growth and directs resources. Removal of superfluous or unwanted growth reallocates resources that such growth would otherwise consume, to more useful or productive growth. The primary difference is that late pruning happens after dormancy. 

Flowering cherry trees are very similar to fruiting cherry trees, but generate only copious bloom without fruit. Flowering crabapple trees likewise produce only their unique bloom, but without much fruit. Technically, both would prefer dormant pruning during winter. Yet, late pruning immediately after bloom allows them to first bloom as profusely as they can.

Fortunately, flowering but fruitless counterparts of fruitful trees require pruning that is less severe than what their fruitful relatives require. Comparably severe pruning would be too stressful for them after dormancy. However, flowering peach trees can endure harsh late pruning to stub their bloomed shoots. Stubs generate more shoots for bloom next spring.

Late pruning begins as early as spring blooming trees and shrubs finish bloom. Because of warm weather this winter, many are blooming early. Stems of some types work well as cut flowers, either while in bloom or immediately prior to bloom. Once the first few flower buds begin to show color, most buds on the same stem should continue to bloom inside.

Camellias supposedly prefer pruning during their bloom cycle, since they resume growth immediately afterwards. Because such pruning would ruin some of the bloom that is their primary asset, most camellias must tolerate late pruning after bloom. Dogwood, forsythia, redbud, and flowering quince, as well as flowering cherry and flowering crabapple, are likewise tolerant of these technically untimely techniques.

Pollarding Pruning Techniques Remain Controversial

Pollarding is pruning to the extreme.

Olive orchards formerly inhabited some of the regions that became urban in California. A few orchard trees remained within urban gardens of the homes that encroached on them. Unfortunately, for those who did not utilize the abundant olives, these trees were horridly messy. Many decades ago, pollarding eliminated the mess without eliminating the trees.

Pollarding is extreme pruning that eliminates all but the main trunk and a few main limbs. It deprives olive trees of their ability to bloom, by eliminating stems of a previous season that would otherwise bloom during the next season. Fruit can not develop without bloom. For other trees that bloom only on older stems, pollarding eliminates bothersome pollen.

Pollarding has several other practical applications. It confines trees that would otherwise get too big for their respective situations. It enhances foliar color and texture for trees that display colorful foliage through summer, such as Schwedler and Princeton Gold maples. Red twig dogwood generates more colorful twigs, and more abundantly, after pollarding.

For agricultural purposes, pollarding generates lush vegetative growth of white mulberry to sustain silkworms, or other vegetation for livestock. It similarly generates long and thin willow stems for basketry. Various eucalypti rely on pollarding to produce juvenile foliage that is colorful and healthy enough for floral design, or aromatic enough for essential oils. 

Nowadays, pollarding is unfortunately passe and even vilified. Consequently, almost no arborists learn about it. Because it is technically disfiguring and potentially unsightly, it is undesirable for many situations. Annual repetition is needed to prevent bloom or fruiting. Otherwise, restorative pruning or more extreme pollarding eventually become necessary. 

For pollarding, proper technique is imperative. Such severe pruning must happen during winter dormancy. It would it be too stressful during vascular activity. Besides, bark would be very susceptible to scald if so suddenly exposed during warmer and sunnier weather. Pruning cuts must be very neat, and back to any old pollard cuts, without stubs to inhibit healing.

Only Arborists Specialize In Trees.

Big trees need real arborists. Even the best of gardeners should not be expected to perform major specialized arboricultural techniqes.

Just as most problems in landscapes are caused by maintenance gardeners hired to maintain the landscapes, many of the problems with trees are caused by those hired to fix such problems. Arboriculture, which is the horticulture of trees, really should be performed, or at least directed, by professional arborists. It is too specialized to expect it to be done properly by those lacking education and experience.

Even the few proficient gardeners who can perform most aspects of gardening well are not likely as proficient with proper arboriculture as arborists are, not only because it is so different from other gardening, but also because of the techniques and tools involved. Gardeners compare to arborists something like those who clean windows on skyscrapers. Custodians who clean windows on the highest floors from the inside probably would not want to clean the same windows from the outside like window washers do. There are just too many differences in the two related but vastly different types of work.

Arborists who are certified by the International Society of Arboriculture, or ISA certified arborists, are the most qualified to assess the health, stability and structural integrity of trees, and to then prescribe any necessary arboricultural procedures. These arborists have passed an examination of their arboricultural expertise, and maintain their certification by continued involvement with ISA educational seminars, workshops and classes.

Arborists and the tree service businesses that they are affiliated with are easy to find at the website of the ISA at www.isaarbor.com. They can be found directly by name, or regionally by city or ZIP code. The website is also an excellent resource for those wanting to learn more about trees and the importance of proper arboriculture.

Trees are the most substantial features of landscapes, and are really worthy of more respect than they commonly get. Structural problems or instability can be serious problems, not only to the affected trees, but also to anything around them that might be damaged or destroyed by falling limbs or even entire trees. Proper arboriculture helps to keep trees healthy and reasonably safe for many decades or centuries.

Six on Saturday: HAPPY NEW YEAR!

HAPPY NEW YEAR!

Happy January too! Happy Saturday! Really though, what is all the fuss about? There is nothing new about this. New years have been arriving annually for as long as anyone can remember. New days arrive daily. New hours arrive hourly. In fact, a new one just began within the last sixty minutes or so. Perhaps that justifies trying to be happy whenever we want to. I digress. My Six for this Saturday are irrelevant to this New Year, and actually, are not exactly happy. All six pictures involve just two trees, a valley oak, Quercus lobata and a coast live oak, Quercus agrifolia.

1. Thunderstorms are rare here. A real doozy arrived on Christmas morning though. The wind could have landed Rhody in Oz. This distinguished valley oak lost two major limbs. 

2. The worst of the damage is just above and slightly left of the center of this picture. The large limb that fell from there clobbered another large limb that was closer to the center.

3. Can you identify what this picture shows? The pair of short yellow lines near the lower center of the picture is a clue. That is the dirty tip of my left boot in the lower left corner. 

4. Tilting the camera from vertical reveals why I could not return to work after what was supposed to be a quick errand. This large coast live oak fell and totally blocked the road.

5. But wait, there’s more! This was more than we could move efficiently with the tractor. Two crews, working at both ends, took all day to clear it all. Another trunk fell to the left. 

6. The trunks had been deteriorating for decades. The moisture of the adjacent drainage ditch accelerated rot. All that evergreen foliage finally got too heavy when wet from rain. 

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

ISA Certified Arborists Know Trees

Arborists work with the big trees.

Arborists are horticulturists. They just happen to be more specialized than most. Many or most other horticulturists work with flora that they engage from the ground. Arborists work exclusively with trees. Some must leave the ground to do so. The most experienced and educated arborists are those certified by the International Society of Arboriculture or ISA. 

ISA certification requires an arborist to pass an examination of arboricultural proficiency. Continued participation with ISA endorsed classes, workshops or seminars is necessary to maintain certification afterward. Arboricultural industries are demanding, with stringent professional standards. Certification with such industries is correspondingly demanding.

General information about the International Society of Arboriculture is available online at isa-arbor.com. This site, although designed for arboricultural professionals, is informative also for those who must procure the services of an arborist. The directory of ISA certified arborists can identify local arborists, as well as the tree services with which they affiliate.

Although arboriculture is pertinent throughout the year, it seems to become more so with the first storms of autumn. Some trees prefer dormant pruning during winter. Others might perform best after summer pruning. Various trees have various preferences. Regardless, the need for arboriculture becomes apparent as weather breaks limbs and uproots trees.

Trees are innately the most substantial and relatively permanent plants in home gardens and landscapes. Unlike annuals and some perennials, trees are not disposable, or easy to remove if they become too problematic. Many eventually get too big for those who are not experienced arborists to engage. That is why too many trees need professional help. 

Many municipalities require permits for the removal of significant trees. Inspection by ISA certified arborists, and associated reports, are generally prerequisites for the issuance of these removal permits. Some municipalities are more protective of trees than others. ISA certified arborists try to be familiar with the ordinances of the various municipalities in which they work.

Six on Saturday: Oops!





These Six for this Saturday are a minor collection of embarrassing but otherwise useless images that are perhaps too amusing to merely delete. Some had been accumulating for quite a while. The first may not seem like the worst, but is associated with a more embarrassing picture from another ‘Six on Saturday’ of last April. That entire procedure was just too dysfunctional to write about. The fifth picture was actually planned, and should actually work, regardless of how silly it looks here now.

1. Black cherry is so rare here that I met only one in my entire career; and sadly, it needed to be removed. What I did not show at the time was how close this bit got to an adjacent parked car.

2. Arborists who cut down bigger trees for us are remarkably proficient. However, after removing this canyon live oak without any damage, they piled the firewood onto one of my hydrangeas.

3. It made sense at the time. There are two rows of canned plants on top of this retaining wall. Roses are in the sunnier outer row. Now, they need to be deadheaded; but I can not reach them.

4. Land is famously expensive here. Nonetheless, we get it delivered for free whenever we want it. The quality is good, and on rare occasion, it comes with surprises such as callas or narcissus.

5. This ungrafted flowering cherry tree would not stop suckering. Now that it is succumbing to scald, one of its own suckers is groomed and staked to replace it. This stake is nailed to the tree.

6. While unused during the past year, the buildings at work were neglected more than the landscapes were. No one was here to tell us what this Boston ivy was doing on this exterior stairwell.

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/