The other day I planted this Eastern White Cedar (Thuja occidentalis) on a slab I picked up from Aichi-en in Nagoya, Japan. I believe the slab is made of concrete, although the artist did a very good job of giving it a natural form and texture.
I had the help of a friend who has much more experience planting trees on slabs than I do. I was expecting to have to make a retaining wall out of muck like Bjorn does for a white pine in this excellent video, but I learned that this step is completely unnecessary with healthy Thuja because of its incredibly dense root characteristics.
Unfortunately I didn’t get many pictures of the process because I was busy working on the tree 🙂 However, the key points to planting Thuja on a slab are as follows:
- The material should be well established and have a dense, fibrous rootball. Most Thuja can produce this in two years of growth in a coarse bonsai soil such as a lava rock or pumice based mix.
- Do not disturb the rootball any more than is necessary. In other words, don’t rake the whole thing out. This will weaken the structure of the rooball and will make it difficult to keep it intact once planted on the shallow stone.
- Remove thick, downward growing roots.Thuja collected from rocky areas typically have few of these, as was the case with this tree. Once the rootball is shallow enough, leave it alone.
- Trim long, thick roots that extend beyond the desired perimeter of the rootball. Excessively long fibrous roots can be tucked underneath the rootmass once it is placed on the stone.
- Tie it in tight. Drill more holes if necessary.
- Work in soil where necessary, If the rootball is dense and was undisturbed, relatively little soil will need to be worked in near the trunk.
This is a very dwarf and dense variety of Ginkgo that I picked up at a specialized nursery for a good price. I keep telling myself that I will not buy nursery material unless it is exceptional but it is tough to live by this rule!
Anyway, like most dwarf conifers, this specimen is grafted – and the graft is very ugly. I knew this when I bought it, so air layering was definitely part of the plan.
I have air layered a number of trees successfully in the past, and normally start the process in the late spring after the leaves have just hardened off. Of course, there is more than one way to do things in bonsai, and Graham Potter made a video which does a great job of summarizing his approach to air layering. The video can be watched here.
A summary of the key points of his process is as follows:
- Start the layer in the early spring, when the tree is just beginning to show signs of activity.
- Cut away a ring of bark, and scrape away all of the white phloem tissue until you have reached the sapwood below
- Clean cut the top of the ring with a sharp knife
- Rooting hormone doesn’t really help
- Pack the sphagnum moss tightly against the trunk. Good contact between the moss and the trunk is important.
I am keen to try Graham’s approach, because starting the layer as early as possible will give it more time to develop in our short growing season.
The one time I tried a Ginkgo air layer, it failed. The tree bridged the ring wound – probably because I did not scrape away the phloem. When I re-opened the wound, the tree died. However, I know that Ginkgo are conducive to air layering because a friend of mine has layered a pretty chunky branch of a specimen Ginkgo yard tree.
Hopefully this tree continues to bud out and shows some roots soon!
This tree took a step forward over the last couple of weeks, but still has a long way to go. It is one of several Ulmus pumila I got from this old hedge in 2010.
As a side note, this winter I ended up with about 10 kg of Robert Stevens’ Bonsai Aesthetics aluminum wire. This is the first tree I actually tried it out on. It is pretty good stuff… only slightly softer than Japanese anodized aluminum with a bit less holding power, but at a fraction of the price. As is typical with aluminum on deciduous trees, I found myself using wire about 1/2 the thickness of the branch to achieve the desired bending power. It is worth noting that this wire is pure glossy black, as opposed to the copper-ish colour of Japanese aluminum wire. It will be interesting to see how the colour stands up to the elements over this growing season.
Root work came next. This is the first time that this tree has had focused root work since coming out of the hedge. Almost all of these elms had massive taproots. This one needed some work with the reciprocating saw and a die grinder to further reduce the taproot. Furthermore, a few excessively long roots had to be pruned back. This may look extreme, but every root I have cut back on one of these Siberians has produced new roots near the cuts – even tap roots 15 cm in diameter.
This Elm has an excellent trunk for a classic informal upright design, but the nebari is terrible due to the presence of large taproots. On an informal upright elm, the nebari is one of the most important features. Root grafting may be in this tree’s future.
The main purpose of this repot was not horticultural, but rather to adjust the planting angle of this Dwarf Japanese Yew. It has been tough to get this tree at the right angle due to the presence of thick sections of downward growing trunk which I have been rather timidly chipping away at (the tree was developed as a ground layer). You can read more about the history of this tree in my progressions page. This tree has been slow to develop, largely due to the long period of time spent replacing the root system. It is finally at the point now where I can solely focus on its development as a bonsai. It does admittedly have a few years to go before it is show ready.
My Thuja are starting to lose their winter colour, so I figured now was as good a time as any to make my first attempt at grafting hinoki foliage to this old bare tree.
The type of graft I attempted was a type of side veneer graft, as shown in the image below.
To be honest, I am not feeling very confident about these grafts. I did the best I could, but I feel that I am at a big disadvantage without having a greenhouse. But nothing ventured, nothing gained – right? If these fail, I will try approach grafting and possibly some more side veneer grafting in the late spring.
Perlite is readily available and cheap, but I’ve never really used as a soil component because it is too lightweight (floats/doesn’t weigh down the pot) and it is really ugly.
However, I’ve noticed that there seems to be a practically religious following in Italy of bonsai growers who swear by using pure perlite for rehabilitating recently collected yamadori.
As evidence of the powers of perlite, check out these amazing pictures taken from this thread on the forum Master-Bonsai.com, which is administered by Andrea Meriggioli (a young professional in the very serious Italian bonsai scene):
I’m not sure if perlite can be given all the credit for this pine pulling through. Andrea also used a number of tonics when he planted the tree (“radimix, bioxim, and antym kombu40 etc.”), whatever that stuff is. Nevertheless, it is an impressive story.
The potentilla that is the subject of this post was collected about 10 years ago by a friend of mine. I have admired this tree for some time, as potentilla’s of this size and drama are quite rare. When I had the opportunity to buy it for a reasonable price last year, I didn’t hesitate!
However, this tree has some serious issues and serves to illustrate some limitations of potentilla for bonsai. In a recent post, I said that potentilla are one of my favourite species. They are certainly not perfect, however. Many people will refer to the limited longevity of potentilla. While they are hard to kill, their weedy growth habit is subject to dieback. Their biggest issue, however, is wood rot. This tree is a perfect example of the issues that arise with potentilla over time.
When designing potentilla bonsai as a deadwood species, you must be very conscious of the soft wood. It is nowhere nearly as robust as the deadwood of other deadwood species such as Thuja and Juniperus, and requires extra care. This means treating at least once a year with a penetrating wood hardener, and keeping the deadwood clean and dry. This is the product I like to use.
These techniques were not applied to this potentilla over the last decade, and as a result it has lost much of its structural integrity as a result of rot. Some of the fine jins near the base of the tree also crumbled away when I first laid hands on the tree last summer. The tree is literally falling apart. To make things worse, was planted in a very mucky organic soil mix which takes a long time to dry out.
The purpose of this spring work was mainly to take steps to minimize the advancement of the rot by doing the following:
- Remove as much of the rotted wood as possible
- Bareroot the tree and replace the soil with a coarse inorganic mix
- Plant the tree more upright so that the deadwood is far away from the soil surface
- Treat with limesulfur, then wood hardener
The video clip below shows the extent to which the rot has compromised the structural integrity of the tree.
Today is March 12th, and my Ginkgo is already showing green buds. This means it is the ideal time to repot. This is more than one month earlier than I am accustomed to seeing movement on this tree.
The last time I repotted this tree was in 2010, and it was not until April 17th that the buds were starting to move! This seems to be the same throughout the bonsai community… a warm winter means early spring.
I am happy spring is here, but I am always concerned about taking my trees out of winter storage, then having to shuffle them around again when it becomes -15C in April 🙂
Potentilla fruticosa (Shrubby Cinquefoil) is one of my favorite species for shohin bonsai. In rocky northern regions, interesting specimens are easy to find which can be yanked out of the ground like turnips with a nearly 100% success rate. They are not a particularly common subject, but can still be found in bonsai gardens in most temperate regions of the Northern Hemisphere. I’ve seen amazing specimens coming out of North America, Europe, and Japan.
This is one of several small potentilla I collected last spring. In the proper soil they will quickly develop a fibrous root system and are almost always ready for rootwork the following year. Unfortunately (like junipers) collected potentilla may stubbornly hang on to a few long thick roots that can be difficult to chase back. Cutting back roots has to be done with great care because the compartmentalized nature of their growth can lead to dieback of live veins that are critical to the design of the bonsai.
I collected this tree because while crawling around in the mud I caught a glimpse of a twisting trunk hiding beyond the weeds and flakey bark. The initial clean up is one of the most important steps with collected potentilla, because you never really know what you have until you remove the bark and punky wood.
So here we are, nearly one year after collection, and I finally get to see what I brought home with me!
The next step for this tree will be rootwork in the next few days. If the root system does not need major operations, it will grow strongly and I should be able to cut it back hard in the late spring or early summer. Potentilla backbud profusely and reliably, but they need to be cut back quite ruthelessly. After that, the deadwood work will come. I intend to reduce the live veins to emphasize the twists in the trunk.
It is worth noting that potentilla are ridiculously hardy, and I find they are always the first species to wake up in the spring. Some of mine are already leafing out, 2 weeks earlier than normal due to the mild winter we experienced. I usually repot them when the leaves just begin to emerge, although this is definitely not the only time they can be repotted.
On to the next one!
This ramrod straight larch has a fascinating twist in the lifeline of the tree. I saw this tree while out on a hike and was perplexed by the growth of the trees in that immediate vicinity. Many of them (living and dead) within a small area (about 100 square meters) had an intense spiraling grain for no apparent reason. It must have something to do with the way the wind howls through that little clearing… or perhaps it is something else, beyond my understanding. Nevertheless, it is interesting how such a dynamic live vein can give life to an otherwise dull tree. It would make a unique bunjin-gi. This guy was not collected, however. I don’t have permission to collect where these trees are growing, but I still like to look 🙂
Grafted Miyajima White Pine (Pinus parviflora) have a bad reputation because it is difficult to find a specimen with a smooth graft between the black pine base and white pine top. This is probably because the black pine base grows faster and more strongly than the white pine top.
While visiting a private garden in Japan, I saw this masterpiece grafted miyajima white pine. The trunk line was practically flawless, with hardly any swelling or unsightly graft transition (unfortunately not visible in the picture). This is rare even in Japan, making this a very special tree.
To make things even more incredible, the owner told us that this tree had not been detail wired in nearly 30 years! I found that almost impossible to believe. That would be the ultimate display of bonsai maturity and maintenance techniques.
Thuja occidentalis (Arborvitae) is incredibly disease resistant, and there are only a handful of pests that are of any concern to the bonsai grower. One of those pests is the larvae of a tiny moth called the cedar leaf tip miner.
The following excerpt is taken from a University of Guelph Pest Diagnostic Clinic Factsheet on Thuja occidentalis:
Cedar leafminers are tiny moths native to Canada. Damage is caused by the small larvae feeding within the scale-like leaves of cedar. An infestation is usually first noticed in the spring when the tips of some branches begin to bleach and brown. Heavy infestations can cause severe thinning of the foliage.
The article goes on to say that the disease is not a major concern but, for bonsai growers, it can be aesthetically displeasing and can also weaken the tree if left untreated.
The tree below was collected in late April 2011. I suspect that its recovery left its defenses down, and by August the leafminer had established itself.
Treatment of leafminer is relatively simple. Prune away the damaged foliage, and keep the tree in full sun to promote the recovery of the plant’s defenses. A light application of a systemic insecticide such as imidacloprid will seal the deal.
As a preventative measure, Reiner Goebel recommends treating Thuja with a systemic in the spring to avoid unexpected infestations of leafminer.
One thing that I found very interesting on my trip to Japan was the prices of bonsai. Take this stunning little (about 20 cm) japanese black pine below for example: it set the owner back ¥1,000,000 (about $12,500).
Why is this tree so expensive? Probably a number of reasons… small trees seem to be desirable right now, the bark was very good, the nebari and taper were both almost “perfect”, and the branch placement and ramification were outstanding. It is small details like this that make the difference between a ¥10,000 tree and a ¥1,000,000 tree in Japan. Nevertheless, a ¥10,000 tree in Japan is still pretty damn nice 🙂
I wonder if this tree would sell for $12K in North America? Europe? Maybe that isn’t even a fair question to ask given the difference in the markets for bonsai.
Repotting mature trees is different than repotting trees in development. Mature trees are usually repotted for maintenance purposes, so the root work is less dramatic and much less technical than the sort of work used for trees in development. At a recent workshop, I observed the repotting of an extremely root bound imported Rhododendrum indicum ‘Kaho’. This is a species that I have never worked with since I sadly don’t have the proper overwintering environment for azaleas. Still, its fun to watch and learn 🙂