Horridculture – Tree Preservation Ordinances

Padding should protect these London plane street trees from minor altercations with machinery that will be used to demolish the associated buildings and construct new buildings.

Much of my work involves inspection of trees to assess health, stability and structural integrity, and subsequent composition of associated arborist’s reports to document such assessments. These reports are necessary for the issuance of permits to remove mature trees within many municipalities. They are only effective for that purpose if they recommend and justify removal.

If there is nothing wrong with the health, stability or structural integrity of subject trees, removal might be justified for other reasons. For example, the removal of superfluous trees might be justified if it would promote healthier development of remaining trees. Trees that disperse roots that are beginning to damage adjacent infrastructure might likewise need to be removed.

It seems like it is too much to be concerned with for something that property owners should not need permission to remove from their own property. For what people pay for property here, they should be able to do whatever they want to with it. However, mature trees are considered to be assets to their respective Communities, and components of the collective urban forests.

These majorly and justifiably controversial concerns are actually not the the only difficulties associated with municipal tree preservation ordinances.

While a young coast live oak in the extreme corner of my garden was not quite big enough to require a permit for removal, I asked the next door neighbor if he would like it to be removed before the roots damaged his driveway. I explained that if we waited any longer, the tree would be protected, and that a permit to remove such an exemplary tree would not likely be issued.

Tree preservation ordinances are often the motivating factor for the removal of trees before they get big enough to be protected! I was fortunate that my neighbor wanted my oak to stay.

Horridculture – Bad Guys

P91211Roots hold up trees. That is part of their job. They grow along with the trees they support, and disperse as necessary to maintain stability. Trees grown within the confinement of cans (pots) or boxes, and then installed into a landscape, are typically staked temporarily until their roots adequately disperse and stabilize. Once unnecessary, stakes and bindings must be removed.

Mature palms that get relocated are supported temporarily by guy wires. They are just too big to be supported by stakes. Because palm trunks to not grow any wider as at they grow taller, they are not damaged by the sorts of bindings that would damage the fattening trunks of other trees. Like stakes on other trees, guy wires must be removed as they become unnecessary.

Although they can be appropriate in unusual circumstances in which stakes would not be practical, guy wires are rarely used on trees that are not palms. Mature trees that get relocated can be guyed if too big to be supported by stakes. Because trunks and limbs of such trees expand (circumference), it is more important for guy wires to be remove when they become obsolete.

As useful as guy wires can be, they are more often used improperly or inappropriately. Firstly, those who install them rarely do so correctly, with the wires or cables as straight as possible between each end. Cabled anchors are usually pounded into the ground perpendicularly to the direction of the cable, so that the cable merely slices through the soil when tension is applied.

Once installed, cables are very often left in place long enough to constrict the growing trunks or limbs that they are attached to. Cables that apply too much tension or limit the motion of the trees they support (in the breeze) for too long will actually inhibit root dispersion. Trees will only become as stable as they need to be. Besides all this, lingering cables are just plain unsightly.

The cabled trees in these pictures demonstrate another set of problems that should be corrected by simple and necessary pruning, and comparably necessary adjustment of the automated irrigation. Guy wires should most certainly not be necessary for such mature trees of this species, and will interfere with necessary root dispersion without remedying the primary problems.

Firstly, the trees are too low and dense. Even if stability were not a concern, they should be pruned for a bit more clearance above the patio to the right of the picture, and perhaps allow a bit more sunlight to the plants below, even if only temporarily. More importantly, pruning would temporarily decrease weight and wind resistance of the canopies while roots adapt accordingly.

Secondly, the landscape is getting irrigated too much, even for the ferns in the background. This maintains soil saturation so that stabilizing roots can not disperse into deeper strata. Roots that might have extended deeper earlier will drown and rot. Until this happens, excessive irrigation promotes heavy superfluous growth that the compromised root system can not support.

Automated irrigation should be disabled for winter, and operated only manually and minimally if the weather stays dry long enough for the ferns to get drier than they are comfortable with. It can be adjusted accordingly when reactivated in spring. Even before that happens, and roots disperse, the guy wires can be removed as soon as these trees get pruned as they should be.P91211+

Street-Smart Gingko

P91124Much of my work involves street trees. They need more of my kind of attention than most other trees. They must conform to more restrictive limitations. They endure more abuse. They are the most prominent trees on urban properties. Because some are assets of their respective municipalities, they are more stringently protected by local ordinances than other trees are.

I planted quite a few street trees too. While selecting trees for the medians of San Vicente Boulevard in Los Angeles, we considered the clearance of the lowest limbs above the highest truck traffic, the docility of roots under curbs and pavement, the potential for foliar debris, the resiliency to neglect, and the resistance to pathogens. Those were just some of the major concerns.

We sort of wanted them to look good too.

Ginkgoes, at least modern (fruitless) cultivars, work well as street trees. They are tall and slender, and can be pruned for clearance above streets and sidewalks. Their roots are reasonably complaisant, and take many years to displace concrete. ginkgoes defoliate neatly in autumn, with no debris for the rest of the year. They are resistant to pathogens and tolerant of neglect.

They also look great in their monochromatic but brilliant yellow fall color. (Try to not notice all those utility cables.)

This pair of ginkgoes is in front of an old home in town that was formerly the office of the Los Gatos Weekly Times, before it expanded into the larger Silicon Valley Community Newspapers group. Two decades and one year ago, this was where I dropped off the first of my weekly gardening columns, first as hard copy on paper, then on floppy discs. The trees were smaller then.

One day back in about 1999 or so, I stopped by on my way back from delivering rhododendrons and other horticultural commodities from the farm. I was driving the big delivery box truck. I realized how important adequate clearance is when the truck tore a significant limb from the tree on the left. The tree and I both can attest to the resiliency of the species to such abuse.P91124+

Six on Saturday: Tree Removal


The forest is constantly producing trees faster than we can cut them down. Even if we were not too busy with our many other tasks, we are not equipped to safely remove all of the large trees that become hazardous as they mature. Therefore, a crew who is so equipped is sometimes hired, and was here just this last week to remove several locusts, a few bays and a live oak.

1. The 80s are over. Someone painted this water pipe like this so that a crew cutting trees down nearby would not drop anything on it. The crew would have just put an orange cone over it.P91109

2. I was much younger and healthier back in the summer of 1988, when I did an internship with some of the most excellent arborists in the Santa Clara Valley, but I never climbed like this.P91109+

3. These trees are not much more than eighty feet tall, but needed to be parted out over those roofs. They are less than forty years old, from the 1980s or so. The arborist is in the middle.P91109++

4. Locust is unpopular firewood. These locust trees were therefore cut into logs less than seven feet (or 84 inches) long to fit into a pickup for removal, but were then instead chipped on site.P91109+++

5. This structurally deficient oak will eventually need to be removed. For now, it is groomed and lightened for winter storms. It was a nice day at the time, with temperatures in the low 80s.P91109++++

6. Mature bay trees develop distended lignotubers. The trunk of this bay tree was significantly narrower just two feet above this stump. The tree was not much more than eighty years old.P91109+++++



Horridculture – Sealant

P90810++++Grafting compound is a thick sealant applied to a fresh graft union to limit desiccation while the graft knits. A bit more typically gets applied to the cut distal end of the scion. There are various formulations of grafting compound, ranging from something resembling roof patch to a something with the consistency of thick paint.

The stuff, as sloppy and icky as it is, really is helpful. I can not imagine how big orchards were grafted before it was invented.

It is also useful for keeping cane borers out of the cut ends of freshly pruned roses. For those of us who remember how to prune roses properly, leaving only a few thick canes, grafting compound really is practical. I just don’t use it on roses because cane borers are not a problem here.

Since I do not use grafting compound on roses, and the plants that I graft do not need grafting compound, I presently have no use for it. I suppose I could use it on apple and pear trees, but it really is not necessary. When I get around to grafting apricots and peaches, it will only be for a few trees in my own garden, so I will just use candle wax.

This surprises people. At work, I am often asked about ‘painting’ pruning wounds and shiners as trees get pruned, presumably with sealant. Decades ago, it was actually commonly done. Even when I did my internship in arboriculture in 1988, some arborists were applying sealant because it was easier than arguing with their clients about it not being necessary.

The problem with applying sealant to large wounds is that is actually seals moisture within the otherwise exposed wood, and promotes rot. It is best to do nothing, and allow the affected trees to compartmentalize their wounds as they would do naturally if limbs were broken off by the weather. Trees know more about their processes than we do.

X Marks The Spot






Arborists Maintain The Big Trees

91106thumbThe trees know what time of year it is. Even evergreen trees have shed some of their older foliage through late summer. Deciduous trees generally start later, but will be more blatant about their process as they defoliate completely through autumn to winter. Some get strikingly colorful first, as if to brag about it. Foliage is not so important during shorter days and dimmed sunlight anyway.

By the time storms start to arrive later in autumn, trees intend to be ready. There will be less foliage to be blown by wind, or to absorb the weight of the rain. Remaining deciduous foliage is likely to be dislodged by wind and rain before supporting limbs succumb. Trees will be mostly dormant, so will not mind so much if a few minor limbs do happen to get broken. They know their routine.

For many types of trees, this is a the best season for major pruning. While dormant, they are much less likely to be offended by it. In fact, they sort of expect to wake up in spring with a few limbs missing. They do not distinguish what was pruned away from what might have been broken by the weather. Besides, it is better to prune questionable limbs civilly, before they get broken brutally.

Trees that are beyond reach will need the attention of professional arborists.

Arboriculture is merely the horticulture of trees. An arborist is therefore a horticulturist who specializes in trees. They assess the health, stability and structural integrity of trees, and prescribe any necessary arboricultural procedures. They or their associated crews are qualified to perform the work that the trees need. The most proficient of arborists are those who are certified with the ISA.

The ISA is the International Society of Arboriculture. ISA Certified Arborists have passed an examination of their arboricultural expertise, and maintain their credentials by continued involvement with ISA educational seminars, classes and workshops. Information about the International Society of Arboriculture and local certified arborists can be found at their website, www.isa-arbor.com.

Arborists’ View

P91026KArborists see trees very differently from how most of us see them. They know their trees very intimately, and by botanical name. Arborists know how big particular trees get, both tall and wide, and if they are likely to develop structural deficiency or aggressive roots. They can tell us which are deciduous, which are evergreen, and which are messy with foliage, bloom or fruit.

Some arborists are happy to divulge a bit of history of some trees, whether exotic or native. They might tell us where the exotic trees came from, and why they were imported. Some trees were brought for timber. Some were brought for fuel. Some were imported just because they were pretty. Some naturalized, and now impose on the natural ecosystem. Natives try to adapt.

Since they know the innate characteristics of trees, arborists know what their cultural preferences are. They know that some are understory trees that prefer the company of other bigger trees. Many others are those bigger trees, that want to dominate their respective landscapes. Some want plenty of water. Many of the natives do not want much more than annual rainfall.

An arborist might provide you with way more information than you ever thought you wanted about your seemingly innocuous trees.

Besides all that, arborists are a weird breed that really enjoy their work. Arborists like me simply enjoy diagnosing problems with trees, and prescribing corrective arboricultural procedures. Those who climb trees to execute such procedures are much more involved! Their work is as demanding as extreme sports, and they take it very seriously. They must. It is their profession.

This view of a big box elder, Acer negundo, from above, which I got from the edge of a bridge, might be that of just another day at the office for other arborists.

Work Day Renovation Of A Flowering Crabapple

P91020P91020+It is amazing what just a few parishioners and friends can accomplish in just a few hours from about nine to noon on Saturday morning. It is only happens a few times through the year, so we make the most of it to catch up on all sorts of maintenance and projects at Felton Presbyterian Church. (My parish should do this sort of thing.) I was there to work in the minimal landscape.

I started working with this ‘Prairie Fire’ flowering crabapple several years ago. As I pruned for clearance above the adjacent parking spaces and patio, I retained lower growth in the space in between. The tree bloomed too nicely to unnecessarily remove all that was right where it was most visible. Besides, from the patio, it was more visually appealing than a view of parked cars.

Then, I missed a work day. There were plenty of volunteers. There were plenty of power tools. There was plenty of enthusiasm. There was no horticultural expertise. Someone decided that my once exemplary flowering crabapple was in need of pruning, so executed the task with power hedge shears. The damage is irreparable. Lower growth is gone. Upper growth is mutilated.

It was very discouraging. It was done out of season, so I could do nothing to start to repair the damage at the time. There was not much left to repair anyway. I could only let the tree grow through a season so that there would be something to work with later.

Well, this was later. I would have preferred to wait for complete defoliation, but the tree is starting to go dormant now, which is technically good enough. I also would have preferred to prune less away; but really wanted to remove as much of the disfigured growth as possible.

I am less than pleased with the results. With all the disfigured lower growth removed, only the new upper canopy remains. The tree got what my colleagues might refer to as an ‘Ethiopia cut’, which is what much taller trees in Ethiopia get when their lower growth gets eaten by giraffes. It will be a long recovery.

The upper picture is the ‘before’ picture. The bright sunlight at noon does not look so good in the lower ‘after’ picture. I mentioned the Work Day and an update in my other blog, Felton League.


Self Grafted Redwoods


Redwoods are some of the most stable trees in the World. That is partly why they can survive for thousands of years. In my entire career, I have seen very few fall, and only inspected two.

Of those two, one fell because it had co-dominant leaders (double trunks) that fell away from each other, which is more of a structural deficiency than instability. The other, which I suspect was demonically possessed, was a small tree less than thirty feet tall, that literally jumped up out of the ground and onto an Astro van more than ten feet away. A rare ‘updraft’ was blamed.

Almost all of the redwoods here regenerated from the stumps and roots of much older trees that were clear cut harvested a century or so ago. Most of those that grew back with structurally deficient co-dominant leaders are very effectively sheltered from wind by their collective groves. Roots systems are very extensive, very resilient, and too intermeshed to be compromised.

The trunks in the picture above are part of a group of several trunks that grew from roots of the same tree that has been gone for a very long time. All are genetically identical and very close together. They happen to be a focal point of a big patio at a conference center. Although the structural integrity of the limbs within their canopy is a concern, the stability of the trunks is not.

Regardless, I am impressed by their attempt to improve stability. The limb that extends horizontally across the middle of this picture from the trunk to the left grafted to the trunk to the right! It is not uncommon for crossing limbs and trunks to rub through their bark to expose the cambium, but how do they stay still long enough to graft together?!