Tuesday, January 22, 2008
Taming the "Hinoki" Cypress
Chamecyparis Obtusa "Nana Gracilis"
The Hinoki cyprees has long been a favourite of mine for bonsai culture. C. Obtusa is the easiest false cypress to keep alive. My first introduction to bonsai was with this species. Because of this tree's unique characteristics, it has taught me one of the hardest fundamentals to grasp in this passion; patience.
Many report great success in growing it, but unfortunately, it seems to be one of the most difficult to keep in proper bonsai form due to the whirling fan pattern of the foliage.
I believe this statement to be rather harsh, if the tree is left to its own device then yes. This is one of my favourite trees for many reasons. It lends itself well to bonsai culture and a coniferous silhouette can be easily achieved in a reasonable amount of time.
The major styling challenge for false cypress is the fatal combination of rapid growth, die-back from lack of light, and refusal to bud on old wood. If Chamaecyparis isn't pruned constantly, inside and lower branches will die and never grow back, making bonsai maintenence a headache. The tree is best shaped through constant pinching of new foliage - never use scissors to prune as foliage browns where cut. Hinoki cypress also tends to form awkward whorls of foliage if not properly pruned.
After reading that, who in their right mind would take up this challenge? Hopefully with this article I will be able to share my experience in growing and caring for the species and, in doing so remove the stigma surrounding this wonderful underutilized tree.
Although there are many cultivars, not all Chaemaecyparis Obtusa are suitable for bonsai culture, I will only discuss the ones I have had success and experience with. A more comprehensive list can be found at the end of this care sheet. In my opinion the best species to bonsai are the "nanas". This is a dwarf cultivar but lends itself well to pot culture. Although the growth rate is only 1 or 2 inches per year, when compared to 10-12 inches for the non-dwarf cultivars, this characteristic is highly desirable, and manageable.
I have raised the following species: Chamecyparis Obtusa "Templehoff", Chamecyparis Obtusa "Nana", Chamecyparis Obtusa "Gracilis", Chamecyparis Obtusa "Aurea", and Chamecyparis Obtusa "Nana Gracilis" and Chamecyparis Obtusa "Kosteri". The best and my favourite for bonsai is: Chamecyparis Obtusa "Nana Gracilis". It has the easiest foliage to tame, and this is what this article is all about.
As discussed, Hinokis will not back bud on old wood. Although they will bud on "green wood" as soon as the green turns to bark, then the show is over. What does this mean to you? Well it means that during plant selection you will need to be very critical.
The three things we look for in selecting suitable material is: trunk; branch placement; and nebari. Although nebari is an important criteria, I do not base my selection on this criteria alone. Hinokis take extremely well to ground layering, and will grow new roots in a growing season. The tree can be severed after two. This blog entry describes the process and results nicely.
The most important criteria after trunk diameter/movement etc... is, branch placement and foliage. The only way to get a branch where you want/need it, is to have it there. The only grafting method that has demonstrated success in varying degrees is "in arch grafting". So if it isn't there, it won't be in the future for all intent and purpose.
Hinokis do grow in a compact fashion so, a good selection of branches are readily available. One must be able to envision any given tree and be capable of taking this raw stock to the next level. Inner foliage is one of the most important criteria in tree selection when dealing with Hinokis. I would select a tree with good inner foliage characteristics in a heart beat over one that may have all the branches in the right place, or has excellent trunk movement, not that the latter two criteria are insignificant, but IMO inner foliage is essential to future possibilities, and should be protected at all costs.
The tree is home
You have selected a suitable candidate and it is now in your yard. Most feel the urge to take this stock and turn into a Bonsai in the first session, don't.
The first thing that needs doing is to bare root the tree (I use a garden hose and a chopstick) to gently comb out the roots and rid the tree of all the original old soil and place it in a good bonsai substrate. Allot of enthusiast do not endorse this practice, but many of the better learnt do, the reason is simple. You need to be able to control its watering and feeding regimen. Placing a tree in any container with a mixture of soils is a method that leads to disaster, if the old soil is not removed.
The rationale is as follows: The root ball is sitting in old soil; this soil is often a combination of soil and compaction of roots; this compaction is greater just below the trunk and surrounding roots; this compaction will only get worst over time; it is this compaction that will remain wet when the remainder of the pot is filled with a free draining soil; and the latter will in most instances lead to root rot and subsequently a dead tree.
As mentioned all my trees are bare rooted and re-potted in my substrate. A caveat, my substrate contains traces of Myke (for trees and shrubs) which is a Mycorhizae substitute that inoculates the pot. We have heard that this beneficial fungus is normally found with pines, many will inoculate other trees with this fungus. The downside, this only happens when you can collect it when re-potting a pine or other conifers where it is present. My alternative is a commercial product that is available at any time, more important, it works.
After the tree has been re-potted (the only root work I do is remove the tap root if still present), it is thoroughly watered and fed a dose of 10-52-10 at half strength. This is also available as "transplant fertilizer", of which you will pay a premium price for. I buy it by the tub because it is an integral part of my feeding regimen. This initial dose is followed up two weeks later with a dose at full strength. The tree during this period is placed in an area of dappled sunlight. Once the tree has shown signs of recuperation and is actively growing, it gets placed on a regular feed schedule, and out in full sun it goes.
I do not purchase trees out of season. I try to acquire new material before the end of June, for my climate. If I acquire material past this time line, it remains in the pot until the following spring. No work is being conducted on the tree until then, with the exception of removing branches I know I will not need, to allow light to the inner foliage.
So the tree has recovered from its trip into your backyard. During this time frame you have hopefully studied the tree and have a vision of where you wish to take it. All unnecessary branches are removed and the tree left to recover until the following year.
Wiring the tree should never be attempted within three months of re-potting. The care sheet says so, and I had forgotten this information and subsequently lost my very first tree. I had done both at the same time is the past (in the spring), with great success. Unfortunately the winter of 06-07 was a funny winter and several Canadians lost many trees. So the combination of a funny winter along with re-potting and wiring at the same time, led to the tree's demise. Having learned this lesson, I will no longer carry out both at the same time anymore. I now wire all my Hinokis in the fall.
The rationale behind this is: the tree will be entering dormancy; its growth will be slow to non-existent; the wire can stay on the tree longer, giving it a chance to set; Hinokis are extremely flexible and require many applications before a certain branch has set permanently; and by wiring in the fall it does not interfere with spring re-potting.
If Hinokis are left unattended for any length of time, foliage will naturally re-establish their normal growth patterns. As can be seen from this photograph, this type of foliage is not suitable for bonsai as it puts on an unkept appearance, and often the foliage mass is deemed too heavy for the tree's proportions. Appearances aside as the foliage grows from the centres, creating whorls, all foliage below in the shadows of the top layers receive insufficient light and will die off.
On the other hand the foliage on this tree does indeed show signs of maintenance. Although it is still somewhat crowded, it is manageable for a season or two.
The encircled area of this picture depicts what a foliage fan should look like after it has been thinned through pruning. Although pinching is a technique for many trees and will induce back budding, in my experience is is not necessary unless one wishes to redistribute the energy to lower branches, then yes terminal shoots are pinched back.
There are two different types of pruning: hard pruning (removal on branches); and maintenance pruning which is the removal of "branchlets". It is highly recommended to prune on alternate re-potting seasons. I am a firm believer in doing top work one year, and bottom work the following year.
Pruning can be carried out any time during the active growing season right up until mid-August. I recommend hard pruning during the main growth period (as the tree can repair itself more readily) whilst conducting maintenance pruning in early spring at the first signs of growth.
Maintenance pruning is conducted to thin out and tame the fan whorls. One needs to be fairly gentle as these fans are quite delicate. Because of the density of the fans, it is next to impossible to pinch out unwanted growth without damaging the fan/pad. For this I use a pair of good quality pointed scissors, not unlike the ones you use to clip nose hairs. It has been said that using scissors will brown the areas where cut. In my experience with Hinokis, this is not an issue, and it is far safer than trying to pinch. Furthermore, pinching normally refers to the foliage tips, in which case you would indeed pinch. The aforementioned pruning takes place at the base of "branchlets" and no ill effects will come from this practice. Take a look at a foliage whorl and you immediately see what I mean.
Pruning Hinokis is not much different than thinning out any other branch. What you aim for is alternate foliage pads along the branches. This may seem simple and in some ways it is, but it is anything but. Future styling consideration need to taken into account e.g where will a bend be? It is not practical to remove a fan in favour for another if the chosen one will be on the inside of a curve in a later design, which will cause the removal of two whorls. Remember foliage on Hinokis are at a premium. Didn't I say Hinokis would teach you wisdom and patience?
Because of Hinokis uniqueness (die back of internal foliage), foreshortening of the branches will need to/more likely to take place. The selected fans are gently cupped in the hand using the index and major finger to hold the fan whilst the thumb spreads out the fan. This gives you an indication of the space this fan will occupy after wiring in fall.
Each fan is then selectively pruned with scissors just like any other branch. Each fan is a series of miniature fans all growing from one another. In turn each one of these needs to be thinned out. It is not uncommon to spend 4-10 hours pruning a tree.
This picture depicts a more or less properly pruned tree, the yellow area gives a representation of what a fan should look like after maintenance pruning was carried out.
Active growth period
During this period the tips of the fans can be pinched out to redistribute the tree energy to selected areas. Hinokis like all apically dominant trees need the strong and medium areas constantly pinched back to promote growth in weaker areas.
During this time frame wired branches can be repositioned slightly. I rotate my trees weekly so they receive an even distribution of light.
Pruning versus Pinching
Is there a difference? Well yes there is. Constantly pinching Hinokis will soon render a branch without foliage. You might say how is this possible? Well we know Hinokis do not back bud on old wood. Therefore no new growth will take place or extend past the "pinch" so to speak. How is this possible you might ask again? Well you removed all "terminal" growth in favour of lateral growth. This in turn develops "poodle like" pads of foilage versus branches with foliage perse. Continued pinching results in tufts of foliage on the end of branches versus creating branches, which in turn come from "new foliage", in our case fan whorls. Below is an excerpt of an old discussion that took place.
Boon's approach is to treat the foliage areas more like the ramification of deciduous foliage areas. That is, the deliberate structuring of secondary and tertiary branches and twigs all the way out to the final leaf. Have you ever seen a well ramified Trident maple? They are breath taking. Even when in foliage you can see the entire structure of the foliage area. It seems an almost endless forking of tiny branches finishing in a flurry of minuscule leaves. In junipers you accomplish this not by pinching, but by deliberately selecting each green shoot using sharp fine shears, either keeping or removing the shoot by cutting it off at its base. No pinching except perhaps in the scaffolding stage where you are just selecting places for secondary branching, and browning isn't an issue because the tree isn't ready to show anyhow.
Now this may seem like a daunting task, and in fact it is. Jim (Jim Gremel) said they spent something like nineteen hours pruning three of his trees. You start at the primary branching and follow out to the secondary branching where you begin to encounter green shoots. Most of the time the small green shoots in the axils of the branches is removed to maintain the fork. As you get to green shoots and wood that has just lignified (browned), you begin the process, left-right-left-right- up, left-right-left-right-up, or whatever pattern works for you. This is repeated for every foliage of the tree. Rather than indiscriminate pinching that is mindless and leaves a cushion, you get a structure that you can see through that is light, delicate, and probably most important- maintainable. Foliage area extension can be controlled by simply pruning harder to head back to secondary branching and thus shortening the branch with almost no adverse consequences. Trees treated this way can be shown every year.
Chamaecyparis Obtusa "Kosteri"
Although it can be used for bonsai culture, I find the growth pattern too coarse and would defintely present a challenge, when compared to the "Nana Gracilis"
Chamaecyparis Obtusa "Aurea"
Although this specimen shows a coarse structure, it does possess the same attributes as the "Nana Gracilis". However, it is unique in its growth pattern as all new growth is a beautiful golden colour whilst old growth is a dark green. To many, varigation in bonsai is taboo and I support this, but this tree makes a fantastic addition to any landscape, where the tree is maintained using Japanese Gardening Techniques.
Chamaecyparis Obtusa "Gracilis" is not "Nana Gracilis". The "Gracilis" will grow much larger than the "Nana" but more important is how the foliage grows on a "Gracilis" which is straight up and down when compare to the whorls of the "Nana". This is not a major draw back but needs to be considered as the majority of the branchlets will need to be wired in a horizontal plane. Furthermore, do not remove any foliage growing beneath the branchlets. Once it has been turned to a horizontal position, it now becomes a side. It goes without saying that any branch growing beneath a main branch is indeed removed.
Hinokis benefit of a dose of Epson Salts every month or so, @ a rate of 1 tbs to one gallon of water. It turns the foliage a vibrant dark green and at times (dependent on cultivars) will bring out blueish hues.
Bonsai Clubs International Care sheet
Photos courtesy of Iseli Nurseries