New Canes Replace Old Canes

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Well groomed canes are not overgrown.

Heavenly bamboo, or simply ‘nandina’, is one of those many plants that almost never performs like it should. The intricately lacy foliage is so appealing while plants are young, and changes color with the seasons. The red berries can be comparable to those of holly. Unfortunately, healthy plants grow, and then ultimately get shorn into globs of disfigured leaves and stems.

The same abuse afflicts Oregon grape (mahonia), mock orange (philadelphus), forsythia, lilac, abelia and all sorts of shrubby plants that really should be pruned with more discretion. Their deteriorating older stems should be pruned to the ground as new stems grow up from the roots to replace them. It is actually not as complicated as it seems.

This pruning process, known as ‘alternating canes’, prunes the plants from below. It is a standard pruning technique for maximizing production of blackberries, raspberries and elderberries. It is similar to grooming old stalks from bamboo and giant reed, even if it does not prevent them from spreading laterally.

The deteriorating older stems, or ‘canes’, are easy to distinguish from newer growth. Old canes of Heavenly bamboo and Oregon grape become heavy on top, and flop away from the rest of the foliage. Old canes of mock orange and lilac get gnarled and less prolific with bloom. Aging abelia and forsythia canes become thickets of crowded twigs.

The newer stems are likely a bit lower, but are not so overgrown. Since the foliage is not so crowded, it is displayed on the stems better. Their blooms or berries are more abundant. By the time new growth becomes old growth, there will be more newer growth right below it. In fact, the regular removal of aging canes stimulates growth of new canes.

This is the time to prune Heavenly bamboo and Oregon grape, just because the oldest foliage is as bad as it will get after the warmth of summer. Mock orange, forsythia and lilac should get pruned while dormant through winter, but are commonly pruned just after they finish bloom early in spring. Abelia should probably wait until spring because new growth can look sad through winter.

Mature Trees Need Professional Help

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Arboriculture is specialized horticulture of trees.

Arborists are horticulturists who are specialized with the horticulture of trees, which is known as arboriculture. In urban gardening, they are not as familiar as gardeners who mow lawns and tend to the annuals, perennials and shrubbery that are close to the ground; but they should be. The trees that arborists maintain are the most significant features in most landscapes.

Bad annuals or poorly tended lawns can get unsightly, but are not too hazardous. However, a tree can be extremely hazardous if it becomes unstable or develops structural deficiency. Falling trees or limbs are very dangerous, and can cause all sorts of damage to anything within reach. Arboriculture is therefore the most important horticulture in home gardens with trees.

Sadly, many trees are severely damaged by improper pruning, which is often performed by those hired to prune them. Some get pruned too severely, or get pruned in the wrong season. Others do not get pruned aggressively enough. Either way, many get structurally compromised so that they drop limbs as they mature. Some trees get damaged too severely to salvage.

This is precisely why arboriculture should be done by qualified arborists. Unfortunately, finding such an arborist may not be as easy as it would seem to be. The industry is notoriously overrun with ‘hackers’, who are unfamiliar (and often unconcerned) with what trees need, and how trees respond to improper pruning.

The International Society of Arboriculture, or ISA, certifies arborists who pass an exam of arboricultural expertise. ISA certified arborists maintain their certification with regular involvement with the ISA, which involves arboricutural seminars and classes, as well as networking with other professional arborists. Certified arborists can be found at the website of the ISA at isa-arbor.com.

A Strong Foundation

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Before: Camellias left the foundation exposed a long time ago, but instead obscured the view from the windows above.

‘Foundation planting’, which most of us think of as vegetation intended to merely obscure a foundation behind lower and prettier plants, has a simple utilitarian origin. Before homes were so commonly outfitted with rain gutters like they are now, densely shrubby foundation plantings diffused water that fell from eaves, and limited splattering of mud onto foundations and walls.

Nowadays, foundation planting only needs to look good, and maybe obscure crawlspace vents or exposed undersides of decks. They might be allowed to get as high as window sills, or higher.

These camellias got more than a bit too high. They had not obscured the cinder block foundation in a very long time, and did not contribute much to the shingled wall above. What was worse was that all of their best foliage and bloom obscured the view from the window above, and obstructed sunlight to the interior. They were impressive specimens, but were not doing their job.

We tried to prune their canopies lower and thinner, in order to promote more lower growth that we could prune down to later. They responded by merely replacing what was pruned away, exactly where it was pruned away from. We considered relocating the camellias to where such big and lanky camellia trees would be desirable, but they are too old and firmly rooted in place.

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After: Camellias can either start over or die.

The only option was to coppice them. It was quick and easy. We cut them to the ground with the expectation that they will either regenerate from their stumps or die. If they die, we will not miss them. (Okay, I might.) The new growth will obscure the foundation well, and after a few years, should resume blooming. They will be patchy if some but not all do survive, but we tried.

The remaining sculptural specimen obscures no windows.

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Stumps are a few inches high. Any new growth should hopefully develop on top, just above grade.

Silver Lining

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This little silver dollar tree did well with a second chance.

Among the more than seven hundred species of Eucalyptus, nomenclature gets confusing. It certainly does not help that some species have multiple common names. Eucalyptus cinerea is a rather distinctive species with at least two equally distinctive common names. The problem with these names is that, although sensible in Australian, they are not so sensible to Californians.

‘Mealy stringybark’ is a name that must describe something of the physical characteristics of the species. The bark is rather stringy, but no more stringy than that of so many other species. The glaucous foliage might be described as mealy in Australian English. ‘Argyle apple’ is a weirder name. Again, it must make sense in Australian culture. I just know it as ‘silver dollar tree’.

A few years ago, I acquired a severely disfigured and overgrown #5 (5 gallon) specimen of silver dollar tree, along with three comparable specimens of dwarf blue gum, Eucalyptus globulus ‘Compacta’. They were about to be discarded from the nursery where I found them. They got canned into #15 cans, and coppiced back to their distended lignotubers. All regenerated nicely.

Two of the blue gums found appropriate homes. One remains here, and was coppiced again last year. The silver dollar tree stayed late too, but happened to get planted into a landscape last autumn. It is developing into such an appealing tree that one would not guess that it had experienced such neglect and subsequent trauma. The exemplary silvery gray foliage is so healthy.

As it regenerated after getting coppiced, the strongest of the new stems was bound to a stake to form a single straight trunk. All smaller basal stems were pruned away after the first season. The little tree cooperated through the process, and now lives happily ever after. I still do not know its name.

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Silver dollar tree produces strikingly silvery foliage.

Dago Wisteria

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All this bloom will eventually be fruit.

My colleague down south and I have completely different gardening style. He is a renowned landscape designer, so his home garden is as elaborate as the landscapes he designs for his clients. I am primarily a farmer of horticultural commodities, so my home garden is very strictly utilitarian, with few items that are grown just because they are pretty.

My colleague’s garden is outfitted with a very well built pergola over the patio at the rear of the home. Six common Chinese wisteria were installed to climb the six supporting post and sprawl above. Their cascading spring bloom is both spectacular and alluringly fragrant.

Of course, when I saw that pergola while the wisteria were still young, I thought that it would be ideal for Dago wisteria, which most of us know simply as grapes. They climb like Chinese wisteria. They bloom with somewhat pendulous floral trusses that . . . sort of resemble wisteria bloom. Although they lack color and fragrance, they provide an abundance of fruit.

Now I get to work with some real Dago wisteria. It was planted years ago by someone who did not stay to maintain it. It got rather overgrown and gnarly before I pruned it into submission. Without a pergola, I extended vines from the rail fence that the main vines climb, over to a banister on the upper floor of an adjacent building. It works something like a pergola.

Because I do not know what cultivar of grape the vine is, I do not know what pruning technique it prefers. I happened to leave long canes last winter, just because they reached the banister on the opposite side so well. Now, the bloom is so profuse that I am concerned about the weight of the subsequent fruit pulling the rail fence over!

Multi Trunk Trees Seem Natural

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Overgrown shrubbery becomes multi trunk trees.

For several years in the late 1960 and early 1970s, European white birch were trendy. Most lived in ubiquitous groups of three. Where three did not fit, a single multi trunk tree, typically with three trunks, was a popular option. Each multi trunk tree provided as many trunks as a few single trunk trees. For these particular white birch, the elegant white trunks were their most appealing feature.

Multi trunk trees, which are popularly known as ‘multis’, are only structurally different from their counterparts with single trunks. Multi trunk crape myrtle are genetically identical to crape myrtle of the same cultivar, but with single trunks. The only difference is that multi trunk trees branch at ground level, instead of at the top of a single straight trunk. Each needs to be pruned to the desired form.

Multi trunk birch, paperbark and lemon gum exhibit appealing bark. More trunks display more bark than single trunks. Multi trunk strawberry tree, olive and oak exhibit appealingly sculptural form. Cork oak and crape myrtle provide both appealing bark and sculptural form. Silk tree, acacia and deciduous magnolia display their bloom more effectively with lower and broader multi trunk form.

Trees get help to develop into a desired form. European white birch, lemon gum and silk tree are more likely to develop single trunks naturally. Coppicing compels them to regenerate with several trunks. Conversely, olive, crape myrtle and strawberry tree develop a few trunks naturally. Single trunk trees need thinning to remove the superfluous trunks, and staking to straighten a single trunk.

In home gardens, multi trunk trees sometimes evolve from overgrown shrubbery. Pineapple guava may be shrubby for may years before lower growth gets pruned away to reveal sculptural trunks within. English laurel that gets too overgrown for containment pruning might become a delightful multi trunk tree instead. It will be pleased to grow freely from the top if lower growth gets pruned off.

Multi trunk trees are no more natural than trees with single trunks are, but they seem to be.

Horridculture – Jumpin’ Juniper!

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This is the backside of some of the better junipers!

Junipers have a bad reputation. They earned it at a time when they were too common. Too many were installed into situations that they were not appropriate for. As they grew, they were unpleasant to handle. If not handled enough, they became overgrown and shabby. Once that happened, there were nearly impossible to prune back into confinement without being ruined.

I was never one to completely subscribe to that bad reputation. There were just too many junipers that I really liked, particularly the Hollywood juniper and the Hetz blue juniper. There were a few that I disliked, and I still loath the common tam juniper, but they were in the minority, and happen to be the same sort that are becoming more scarce.

For landscape situations that they happen to conform to, there really is no reason for junipers to be any less appropriate than any other genus is. They are happy with local climates and soil types. Once established, they do not need much water at all, and many need no supplemental irrigation. They last for a very long time. Best of all, they need only minimal maintenance.

However, even some of the best junipers are not perfect. I know. I just needed to work with some that were installed in 1980, and, except for getting pruned back around the edges, were completely ignored. After days of trying to tame them, I can not longer deny that some of what I have not wanted to believe about them is very true.

Besides all the trash and road debris that had been dumped into them during the past four decades, they were thickly infested with Himalayan blackberry. Removing the bramble was not only wickedly unpleasant, but it exposed bare spots where juniper foliage had been shaded out. Removal of a few junipers that had been overwhelmed and died left even more bare spots.

Well, I could not just leave all the dead twiggy growth under the bars spots, so tried to remove some of that too. That only exposed more of what what under and behind it, and caused the well foliated stems above to sag into the whole mess. In the end, the junipers are an unsightly mess, and I know that they will stay that way for a very long time.

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Removal of all the bramble and dead junipers exposes a lot of bare branches.

No One Likes A Sucker

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Citrus have been bred for centuries.

Citrus trees that are grown from seed take a few years to mature enough to produce fruit. As they mature, the juvenile stems are outfitted with thorns that are even nastier than thorns on adult growth! Because most citrus has been extensively bred, seed grown trees are very likely to exhibit genetic variations. This is why citrus trees are cloned from stems of stock trees.

Cloned trees are genetically identical to their parents, so will always produce the same fruit. They are cloned from adult growth, so do not need time to mature from juvenile seedlings. They can therefore bloom and produce fruit as soon as their roots are ready. Also, their thorns are less dangerous.

Cloning citrus is not as simple as rooting them from cuttings though. With few exceptions, citrus trees are grafted onto genetically different rootstock. Most citrus trees in home gardens are grafted onto dwarfing rootstock that limits the size of the trees when mature. Orchard trees are grafted onto rootstock that allows them to get significantly larger.

The graft union, where the upper part of a grafted tree is attached to the rootstock, is typically visible just above the ground. The base of the trunk below the graft union is typically a bit more stout than the relatively lean section of trunk above the graft. Trunks of old trees are often more furrowed below the graft union than above it.

Sometimes, the rootstock tries to do more than provide roots. It can produce stems from below the graft union, known as ‘suckers’ that can potentially compete with the grafted portion of the tree above. Unfortunately, understock grows more aggressively than most types of citrus, so can overwhelm and shade out the desirable parts of an otherwise healthy citrus tree.

The most common understock for citrus produces suckers that are outfitted with unusually big and wicked thorns that are not to be messed with! If fruit develops, it seems to be humongous and disfigured lemons that lack flavor. Before they overtake good citrus trees, suckers should be pruned neatly away as they develop, without leaving any stubble to regenerate more sucker.

Horridculture – High & Mighty

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Camellias are pretty this time of year, but . . .

Camellias have been blooming for a while now. I typically get rather good pictures of them. The pictures are nothing too artistic, of course, and are intended to merely exhibit the floral color and form. A bit of the glossy foliage in the background is nice.

The picture above is not so useful for exhibiting much of the floral characteristics. Even the pink color is muted by the sloppy background and gray sky above. Zooming in would not have corrected the positioning of the flowers. I simply could not get close enough to do any better.

That eave in the lower right corner of the picture is above a two story building. That is where all the blooms of this particular camellia shrub are located. With so much of the lower growth shaded out and gone, this shrub is more like a small tree. The bloom is too high up to be appreciated. The picture below demonstrates what it all looks like without zooming in.

If there were windows facing this big camellia shrub or tree, I would likely prune it only a bit lower, just to keep it below the eave and within view of the windows. Without windows, I know that I really should prune the tall trunks back to what little lower growth remains, in order to promote more growth and bloom closer to ground level where it can be appreciated.

The difficulty I have with pruning it back is that this big camellia shrub or tree is so impressively big and sculptural, and all the glossy foliage looks so good in the foreground of the rich dark brown wall. I do not know what is more important here, the sculptural limbs and rich green foliage that lasts throughout the year, or the colorful but seasonal bloom.

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There is not much to see from this distance.