Horridculture – Opposite Poles

P90904This is not about North and South. It is about a utility pole and a pole that remained from a redwood tree that was too close to it. One is there to support a variety of cables and a streetlamp. The other just wanted to grow into a redwood tree to join the rest of the forest. One has been deceased for many years or decades. The other was alive just recently, but is now only a stump.

The picture above shows how many cables the utility pole supports, as well as the streetlamp. When I did my internship in 1988, the arborists whom I worked with knew what each of the various cables were for; high voltage, lower voltage, cable television, telephone and whatever else was up there. Fiber optic cables have since simplified the telephone and television cables.

The picture above also shows how the unfortunate redwood tree needed to be cut back for clearance from the electrical cables. I was mortified to see this so prominently visible on the edge of a main road, because I should have noticed the problem earlier and just cut the tree down. Not too long ago I was pruning many other redwood trees for clearance from other streetlamps.

Those who pruned it instead, along with any other trees that were encroaching into the electrical cables, were very efficient with establishing clearance, but not so proficient with aesthetics. Obviously, I could not leave this tree like this on the side of the road. Even if I did not care what it looked like, I did not want it to regenerate and immediately encroach back into the cables.

The picture below shows my corrective pruning. The stump is certainly not dead, and will try to regenerate, but will be easier to keep down. If kept down long enough, it may eventually die.

The second picture below shows the stripped trunk in two sections that are nearly eight feet long, and a short bottom section that is a bit more than two feet long. The two long sections are straight enough for gate posts (although there is another plan for them). It is a sad demise for the formerly healthy and sound redwood tree, but became necessary to keep the electricity on.P90904+P90904++


Bad Pollard

P90831KJust about any other arborist will insist that any pollard is a bad pollard. I am not any other arborist. I have no issue with pollarding certain trees properly.

Pollarding is severe pruning that removes all growth that developed since the last pollarding procedure, leaving only a main trunk and a few main limbs. It is done while trees are dormant in winter, and must be repeated either annually or at least every few years, before the resulting growth develops into major limbs. Pruning must be very thorough and neat, leaving no stubs.

Most new growth develops from where older growth had been pruned away during the previous winter, with only a few adventitious stems possibly developing on the main limbs or trunks. Distended ‘knuckles’ develop where this growth repeatedly gets pruned away and regenerates. All subsequent pollard pruning must be done only on the outside of these knuckles, not below.

It may seem easier to cut entire knuckles off with fewer big cuts rather than cutting all the secondary growth off with so many more cuts. However, as new growth develops, the many small cuts on the distended knuckles will be compartmentalized (healed over) much more efficiently than fewer but larger wounds. Wounds that compartmentalize too slowly stay open to decay.

Once pollarded, a tree will always need to be pollarded, or at lease pruned regularly to compensate for compromised structural integrity. Secondary growth is innately vigorous and heavy, but weakly attached to the main limbs.

Pollarding is done to produce an abundance of lush foliage, to produce an abundance of twiggy growth, or to deprive a tree of bloom. Pollarded mulberry trees provide lush foliage to feed silkworms. Pollarded willow trees provide many uniform limber canes for basketry. Pollarded privets are unable to bloom and bother those who are allergic to their objectionably fine pollen.

Well, enough about pollarding.

I pollarded a blue gum, Eucalyptus globulus, for the second time earlier this year. It was done dangerously late in the season, and at the same time that the roots of the tree were brutally damaged by relocation. (It is a canned tree that rooted into the ground.) The tree has no branches, but only a single ridiculously bare trunk with a silly new knuckle on top. Oh, the shame!

As you can see, the unfortunate tree has not grown much since then. It is now getting to be September, so the tree will not be growing much through autumn. As much as I would prefer to pollard this tree annually, I will likely not pollard it this winter, but instead let it grow for another year before pollarding it again. The blue juvenile foliage is exquisitely aromatic, but scarce.

For this picture, I could have moved the tree away from the fence that it is tied to for support, but the barbed wire somehow seems appropriate.

Six on Saturday: The Shining


‘Shiners’ have nothing to do with Rudbeckia hirta, which is commonly known as ‘black eyed Susan’. (Why did rude Becky hurt Susan like that anyway?) Shiners are the wounds left from pruning significant limbs from their supporting limbs or main trunks. They shine most blatantly when fresh, and then fade in the weather.

The best shiners are those that will be compartmentalized (healed over) most efficiently. They should not be cut too deeply, or be left with stubs that interfere with compartmentalization. There is quite a bit of science to shiners.

1. This is a good example of a bad shiner. (I could have gotten a better picture of it, but thought that the sun shining from behind was appropriate to the topic.) This shiner was not made by pruning a limb away from a main trunk, but by pruning a main trunk away from a limb. The main trunk leans over so much that most of it needed to be removed to maintain minimal clearance over a driveway. The only two options were to prune it back the the limb on the left, or remove the entire tree. Because the shiner is wider than the remaining limb, which will become the main trunk, it will take several years to be compartmentalized. By that time, decay will have extended downward from the shiner into the main trunk below.P90824

2. Removal of a limb that was battering the topsides of delivery trucks left the shiner above and left of the center of the picture. The scar to the lower left of the shiner, and another scar farther the lower right, closer to the lower right corner of the picture, were caused by a single altercation with one truck that drove off the edge of the driveway. Since it is not really encroaching into the driveway, or interfering with minimal clearance, this particular damaged limb remains.P90824+

3. This is the thrashed limb that was removed from the limb in the #2 picture above. The freshest damage is still red. This limb had been up above minimal clearance for a few years before the supporting limb sagged with the weight of the growing canopy above. Damage to the trucks is more of a concern than the limbs, so it had to go.P90824++

4. This is another good example of a bad shiner. The main trunk to the right would not have been able to compartmentalize over the stub until it grew out past it, or the stub rotted and fell away. The stub was partly rotten, but also partly viable, with a small branch growing from it. The viable portion would have taken more time to rot away. The whole mess was cut away after this picture was taken; but the resulting shiner that I did not get pictures of has another problem. This picture shows how the stub wraps around the main trunk from behind. The bark compressed between the stub and the main trunk, which is known as ‘included bark’ or ‘bark inclusion’, will temporarily be in the way of compartmentalization of the shiner. Fortunately, the tree is young and vigorous enough to figure it all out.P90824+++

5. What looks like shark jaw bones without the teeth is the callus growth that once surrounded a well cut shiner. After the shiner was cut, and the tree started to compartmentalize over it, the tree died suddenly. As the trunk decayed, this dense callus growth that started to compartmentalize the shiner decayed slower. The uniformity of the callus growth shows how evenly the shiner was cut. I believe that the bottom of the shiner is to the left, but that could be backward. I can only say that the shiner is sideways in this picture.P90824++++

6. Coast live oak, Quercus agrifolia, is the only species in all five of the pictures above, and also provided the biscuits to the lower left and the upper right in this picture. ‘Biscuits’ are sometimes cut to adjust a shiner after the main part of a limb is pruned away, or perhaps to cut a stump slighter lower after a tree is cut down. I really do not remember why I saved the biscuit to the lower left, although I can remember the tree that it came from. The fresher one to the upper right is from the shiner in the first picture #1 above. I kept the Hollywood juniper biscuit to the upper left because I thought it would smell like the related Eastern red cedar (which is actually a juniper rather than a cedar) that cedar chests and closets are made with. The deteriorating biscuit to the lower right is from a very dead white fir that needed to be cut down. I kept it because I happen to be very fond of white firs, but so rarely see them here.P90824+++++

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


Horridculture – Stumpy

P90814Among pines, firs, redwoods and most excurrent trees (with central leader trunks), stubs or stumps of limbs that were shed are common and more apparent than they are among decurrent trees (which branch into many main limbs). The older lower stubs slowly but eventually decay and fall away as the trunks compartmentalize (heal over) where they were formerly attached.

However, wild trees are rarely completely without such stubs. As the older lower stubs are shed, newer stubs develop higher up. The worst of their stubs get pruned away only when more refined landscapes are developed around such trees, and they get pruned accordingly. If the trees get groomed regularly every few years or so, not many new stubs get a chance to develop.

When pruning out viable limbs, they must be cut cleanly from the trunk or supporting limb, without stubs. Since they do not deteriorate slowly before falling away, the trunk or supporting limb has no time to start the process of compartmentalizing (healing) over where such limbs were attached. Cutting away cleanly eliminates as much obstruction to that process as possible.

Pruning necrotic stubs from trunks of excurrent trees is not quite so important because the trunks have a tendency to start the process of compartmentalization as such stubs are decaying, and can actually constrict and crush stubs if they do not fall away efficiently enough. Nonetheless, necrotic stubs get pruned out when trees are groomed, just because they are unappealing.

So, no matter what, stubs should not be left when pruning. It is not complicated. It is actually easier to control a saw when it is up against a tree trunk or main limb. Yet, many who do not know better, and many who really should, more often than not, leave trees looking like this fir tree.

No Cherry On Top

P90811Weeping flowering cherry is another type of tree that almost never gets appreciated like it should. Like so many Japanese maples, they get planted into situation where so-called ‘gardeners’ shear them into nondescript globs of worthless foliage that only get in the way. Some get shorn so regularly that they are deprived of bloom. Their form and bloom are their two main assets.

The climate here is not easy on them either. Although comfortably mild, the climate is also arid. This aridity enhances the potential for sun scald of exposed bark. Because upper limbs bend over to hang back downward, their bark is more exposed than that of upright flowering cherries. Consequently, upper limbs are often scalded and ruined, disfiguring the remaining canopy.

Pruning can be complicated. Removal of scalded upper growth exposes inner growth that is more sensitive to scald. It is sometimes necessary to leave damaged upper growth until it gets replaced from below by newer growth. Regular pruning to remove as much of the superfluous lower growth as possible should stimulate more vigorous growth among the stems that remain.

This is really the best technique for preventing scald among upper growth. It may sound silly, but pruning from below to concentrate growth into fewer stems that extend from or through the top of the canopy keeps the top of the canopy healthy and resilient to scald. It also elevates the pendulous canopy that needs to be pruned very regularly for vertical clearance anyway.

It is not easy to see in this picture, but this small weeping cherry tree is developing two distinct canopies. The original upper canopy was damaged by scald and is now disfigured. It is mostly to the upper left of center of the picture. A more symmetrical inner canopy that is developing where superfluous inner growth was pruned out last winter is evident below and to the right.

If there were not a walkway so close to the tree, and I were not concerned with maintaining vertical clearance, I could prune the upper canopy back over a few years, and subordinate it to the healthier lower canopy as it grows through it. Instead, I will prune out most of the inner canopy, leaving only a few vigorous stems that can replace what is missing in the upper canopy.

There is no need to be concerned with it now. The lower stems are not too obtrusive yet. They can bloom next spring, and get pruned out next summer before they really do get obtrusive.


P90728Without prior notice, I was informed on Friday morning of a workday on Saturday morning at Felton Presbyterian Church. That was yesterday. Since there was no time to get other chores done in advance, I was an hour late. Considering that we only work for four hours between eight and noon, one hour is rather significant. I felt compelled to attend regardless. A few friends who are parishioners of Felton Presbyterian Church appreciate it.
The difficulty of not attending is that there are several other volunteers who do attend, and they all have very different ideas, or no idea at all, about how to accomplish what needs to be done in the landscape. It is amazing how much damage can be done with a few light duty power tools and too much undirected ambition. Even when I am there, it is difficult to convince the others that I know more about horticulture than all of them combined.
For the past several years, I had been pruning a flowering crabapple tree to renovate the branch structure that was mutilated by someone with loppers and power hedge shears. Yes, hedge shears. I had pruned the tree for clearance above a parking lot on one side, and a patio on the other, but with low branches in between to partly obscure the view of parked cars from the patio. Bloom was spectacular, and not compromised by the pruning.
Then I missed a workday. Even though the flowering crabapple tree did not need to be pruned at that time, someone lopped away the lower limbs indiscriminately, and then sheared the top! There were mutilated stubs all over the new exterior of the canopy. Much of the blooming stems for the following season were removed. It was very disappointing to see all of my effort wasted so pointlessly. Now, I need to start the whole process over.
However, when I got there today, a planter box below the crabapple tree was being dismantled and removed. I could not work in the area, so must return to start the process of renovating the crabapple tree. Realistically, it should be done while the tree is dormant in winter, even if it compromises bloom for the following spring somewhat. The tree is so gnarly and congested now that it is unlikely that anyone would notice a few less blossoms.
As frustrating as it can be, we actually get quite a bit done. These lily-of-the-Nile in the picture above were one of our projects many years ago. They were recycled from a garden in Aptos from which they needed to be removed. We split, groomed and plugged them. Most were promptly removed and discarded by someone else who did not realize that we had just installed them. But hey, at least these few survived and continue to bloom.

The Wrong Time For Pruning

80801thumbNot many plants are sensitive to mere heat alone. Actually, many plants prefer warm weather. The difficulty that some plants have with heat locally is that it typically accompanies aridity, and often accompanies afternoon breezes. As appealing as breezes and minimal humidity are to us while the weather is warm, they promote and accelerate desiccation of exposed sensitive foliage.

Pruning, which obviously becomes necessary while warm weather promotes growth, can make plants more sensitive to damage caused by warm, sunny, arid and perhaps breezy weather. It exposes formerly sheltered stems and inner foliage, which are more sensitive than outer foliage is, to more sunlight and drying breezes. Exposed foliage can either desiccate or roast, or both!

A bit of unsightly but relatively minor foliar damage on the extremities of the outer canopy might be only superficial, but major damage can be dangerous. Superficial damage often gets replaced by fresh new growth before it deteriorates enough to expose more foliage and stems below. However, recovery from major damage can be delayed by the distress associated with the damage.

Japanese maple, aralia, philodendron, rhododendron and all sorts of ferns can easily get damaged by increased exposure. Low ferns are not likely to become too exposed by any loss of their own foliage, but often become more exposed by the pruning of plants above them. Like frost damage, foliar scorch might need to be left to shelter remaining foliage until new growth develops.

The bark of many plants, although not susceptible to desiccation, is very sensitive to sun-scald if too exposed. Young and smooth bark is the most sensitive, particularly if it had always been shaded. Scald kills bark and the vascular tissue below. As it decays, it exposes interior wood to more decay that is likely to compromise the structural integrity of the affected stems and trunks.

Pruning during relatively cool weather and while there are a few relatively cool days in the forecast allows foliage a bit of time to adapt to a new exposure before the weather gets dangerous. Through summer, pruning should not be so aggressive that too much sensitive foliage or bark are exposed, even if it is necessary to leave a bit of unwanted sloppy growth to partly shade bark. Aggressive pruning of exposed and sensitive plants should be delayed until autumn, when sunlight is not so intense, and weather is cooler and wetter.

Six on Saturday: Oh, The Shame!


Not my shame of course; but that of the trees in the pictures below.

Do not try this at home. I only did it because I am a horticulturist and arborist; and I happen to be one of the last arborists in America who condones coppicing and pollarding, which are depicted here.

Coppicing is cutting trees or shrubbery down to the ground annually, or at least regularly every few years or so. Some coppiced trees form basal burls or lignotubers. Some just form thicket growth that replaces itself after getting coppiced back to the ground.

Pollarding is similar to coppicing, but rather than cutting all growth back to a stump or stumps at ground level, it involves pruning all growth back to the same distended knuckles at the ends of a few main limbs annually, or at least regularly every few years or so. It is done in such a manner that the pruning wounds are compartmentalized by the new growth of the following year. Knuckles can be elongated by leaving single short stubs.

There are a few reasons for coppicing and pollarding. Some subjects develop an abundance of appealingly lush foliage. Some develop an abundance of appealing or useful twiggy growth. Coppiced red twig dogwoods are much twiggier and more colorful while bare in winter. Pollarded or coppiced willows produce an abundance of canes for basketry. White mulberries are pollarded to provide an abundance of lush foliage to feed silkworms.

I coppiced a Eucalyptus globulus ‘Compacta’ and pollarded a Eucalyptus globulus for two main reasons. Both are such problematic trees that I do not want to plant either into the ground, so must keep them contained. Also, I want the remarkably aromatic juvenile foliage that develops in response to coppicing and pollarding.

1. Eucalyptus globulus ‘Compacta’ coppiced stump. It is not such a great example of a coppiced stump, since the tree did not grow enough two years ago to get coppiced last year. Consequently, the few main trunks that were just recently coppiced are already starting to form their own separate lignotubers on top of the original, which is now rotting below. Soon enough, they will fuse to form a single lignotuber, concealing the evidence.P90601

2. Eucalyptus globulus ‘Compacta’ before getting coppiced. It is quite small for a specimen that was not coppiced last year.P90601+

3. Eucalyptus globulus ‘Compacta’ after getting coppiced. Rhody is not impressed.P90601++

4. Eucalyptus cinerea in need of pollarding. This tree grew too big too fast to survive any longer in the relatively small #15 (15 gallon) can. Fortunately, in just a few days, it will instead get installed into a landscape where it can disperse roots and mature into a normal unpollarded tree. After a few years, it might get pollarded anyway, just to produce silvery juvenile foliage withing reach of the ground, but that is not a concern just yet.P90601+++

5. Eucalyptus globulus pollarded knuckle. This is only the second pollarding procedure for this subject. The first procedure involved lopping the lanky single trunk off right here where the knuckle is now. The multiple limbs that developed were just recently lopped off, leaving this distended knuckle to repeat the process, hopefully annually.P90601++++

6. Eucalyptus globulus pollarded trunk. This is why Eucalyptus globulus should not get pollarded! They look ridiculous if deprived of their naturally elegant form. They do not look much more dignified with multiple pollarded limbs. Oh, the shame!P90601+++++

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


Spontaneous Limb Failure Is Real

90605thumbIt sounds like science fiction, but it is not. Every spring and during particular summer weather, limbs can fall from trees without warning, and seemingly for no reason at all. It happens when least expected, while the weather is warm and perhaps humid, but notably without wind. The lack of wind is what makes it so unexpected. It is a phenomenon known simply as spontaneous limb failure.

Those who witness it might think that the arborists they call to clean up the mess will not believe their descriptions of what happened. Yet, arborists are familiar with it. Quite a few species of trees are notorious for it, especially in urban landscapes where they get watered regularly. Most of such trees are either chaparral trees that do not expect much water, or riparian trees that do expect it.

Spontaneous limb failure occurs as warmth accelerates vascular activity, but humidity inhibits evapotranspiration, which is evaporation from the foliage. Accelerated vascular activity increases the weight of the foliage. Inhibition of evapotranspiration limits the ability of the foliage to eliminate some of the excess weight. Limbs break if unable to support the increasing weight of the foliage.

Spontaneous limb failure is not as easy to predict as the more familiar sort of limb failure that is caused by wind. Limbs that get blown down typically exhibit some sort of structural deficiency or disfigurement prior to failure. Some limbs that succumb to spontaneous limb failure do so as well, but most do not. They just happen to be the healthiest and most densely foliated parts of a tree.

Native coast live oak and valley oak are the two most familiar of the chaparral trees that are notorious for spontaneous limb failure. Native cottonwood, willow, box elder and sycamore are riparian trees that are perhaps even more susceptible to spontaneous limb failure. Sweetgum, carob, stone pine and various eucalypti are some of the exotic trees that might drop limbs spontaneously.

In summer, spontaneous limb failure is less likely as growth slows and limbs strengthen.

Roses Can Not Be Neglected

P80602+Roses are not for the meek. They are too demanding, too sensitive, too thorny, and without their flowers, they are not even very attractive. They have no business in a low-maintenance landscape, or in a landscape maintained by mow, blow and go gardeners. Those who want to grow rose plants for their flowers should be ready to give them what they want, and to prune them aggressively.

The most aggressive pruning gets done during winter dormancy. That process alone can be quite intimidating for those who are just getting acquainted with roses. After seeing them grow through the year, it seems counterproductive to prune big plants back to only a few short canes. Yet, by now, those canes should have produced much taller new canes that are already blooming profusely.

Now it is time to prune roses again, or will be time to do so soon. Deteriorating flowers need to be pruned away to promote continued bloom, a process known as ‘deadheading’. Otherwise, the fruiting structures that develop, known as ‘rose hips’, divert resources and inhibit bloom. Of course, blooms taken as cut flowers leave no hips, but they might leave stubs that may need grooming.

The popular technique of pruning back to the fifth leaf below a hip is not necessarily what roses want. It probably originated from the recommendation of pruning back to a low leaf with five leaflets because the buds associated with upper leaves with three or less leaflets are not as likely to develop into productive stems. However, pruning a bit too low is probably better than pruning too high.

When cutting roses to bring in, it is better to cut long stems, and then shorten them later if necessary. Each stem should be cut just above a leaf so that the bud in the leaf axil can develop into a new stem without much of a stub above it. The cut stem left behind on the plant should not be so long that it extends too far above the canes that were pruned over winter, or becomes crowded.

Crowded stems inhibit growth of vigorous blooming canes, and are more susceptible to rust, mildew and blackspot.P80602++