Archive for the ‘Bonsai Tips with Justin Case’ Category

The Dreaded Fungus   4 comments


When it comes to keeping plants as ornamental’s like Bonsai, watering becomes a problem. Keeping plants in pots can be a problem since most of the watering is done by hand, and from overhead. While for the most part this is not bad for the plant, it can become dangerous because the soil may hold the water for long periods of time causing an environment good for the formation of fungus.
The subject of fungus in plants is a tricky one. We as humans are quick to visualize fungus on our plants as some grotesque looking growth that would be easy to identify as bad for the plant.

This is not the case. Most fungal outbreaks in plants happens with discoloration of the leaves. This happens to perfectly good normal looking leaves and looks as though the leaves are scorched by the sun. This is not the case. I would be willing to wager that most complaints about maples in particular, of browning edges and scorched looking tips is not sun related at all. This is most of the time fungal in nature. If even minimum requirements are met on a healthy maple, and it is hydrated properly and out of the harsh afternoon sun, there is no reason leaves should be browning at all. Routine prophylactic sprays of fungicide will keep a maple looking lush all summer.

The two main culprits for bonsai come from:

Virticillium Wilt

What is Anthracnose?

From the Farmers Almanac:
This fungal disease affects many plants, including vegetables, fruits, and trees. It causes dark, sunken lesions on leaves, stems, flowers, and fruits. It also attacks developing shoots and expanding leaves. It can spread very quickly during rainy seasons.

Anthracnose is a general term for a variety of diseases that affect plants in similar ways. Anthracnose is especially known for the damage that it can cause to trees. Anthracnose is caused by a fungus.

Anthracnose can survive on infected plant debris and is very easily spread. Like rust, it thrives under moist and warm conditions and is often spread by watering.

On leaves, anthracnose generally appears first as small, irregular yellow or brown spots. These spots darken as they age and may also expand, covering the leaves.
On vegetables, it can affect any part of the plant.
On fruits, it produces small, dark, sunken spots, which may spread. In moist weather, pinkish spore masses form in the center of these spots. Eventually, the fruits will rot.
On trees, it can kill the tips of young twigs. It also attacks the young leaves, which develop brown spots and patches. It can also cause defoliation of the tree.

· Remove and destroy any infected plants in your garden. For trees, prune out the dead wood and destroy the infected leaves.

· You can try spraying your plants with a copper-based fungicide, though be careful because copper can build up to toxic levels in the soil for earthworms and microbes. For trees, try a dormant spray of bordeaux mix. (lime sulphur). This should be applied during the leafless winter phase as calcium during summer will strip a tree of leaves in a day.

· Plant resistant plants, or buy healthy transplants.

· Plant your plants in well-drained soil. You can also enrich the soil with compost in order to help plants resist diseases.

· Water your plants with a drip sprinkler, as opposed to an overhead sprinkler. Don’t touch the plants when they are wet.

Some common Maple fungi;
Aureobasidium apocryptum, Discula campestris, Colletotrichum gloeosporioides, Discula umbrinella

Anthracnose fungi can over-winter in buds, twigs, fruit, fallen leaves or petioles depending on which hosts and pathogens are involved. The disease cycle begins in spring when spores are dispersed short distances by water or spread long distances by air to newly forming leaves. Spores are produced within new leaf infections several days to weeks after the initial infection and are further spread to new locations by splashing water.

The disease is most common in spring when new shoot and leaf growth are combined with temperatures ranging from 50-68°F and spring rain. Anthracnose can also re-occur in the summer when cool, wet weather is paired with succulent leaf growth. For ash, maple and oak trees, young leaves and shoots are highly susceptible to infection from the anthracnose fungi, but mature fully expanded leaves are largely resistant. Mature leaves of these trees only become infected through minor wounds like damage from insect pests. As a result, once the weather becomes dry and the leaves mature, disease growth will end, and the tree will replace lost leaves with a new flush of growth. In contrast, anthracnose can continue to progress through summer months on trees like hornbeam.

Leaf spotting and leaf distortion have very little affect on the health of the tree. However if a tree is severely defoliated multiple years in a row, this can weaken the tree. In such cases, opportunistic pests like boring insects or canker causing fungi can attack the tree resulting in more significant damage.

Fungicides are not necessary unless a tree has been completely defoliated several years in a row. Fungicides are protective and need to be applied before symptoms appear on the leaves. Proper timing of fungicide applications can vary widely from growing season to growing season and therefore can be difficult to predict. Chemical treatments include products with the following active ingredients.

§ Propiconazole
§ Thiophanate methyl
§ Copper containing fungicides
§ Mancozeb
§ Chlorothalonil (daconil)

*Always completely read and follow all instructions on the fungicide label.

The following pictures are unfortunately from my backyard.
In maples the first signs will be a curling of the leaves. It will look contorted and like a bird’s claw.

As the disease spreads small patches of the leaf will begin to brown. This may or may not be accompanied by the curling of the leaves. Other symptoms like black edges may show.

As the disease progresses larger brown patches may present themselves as spots on the leaf.
This phase may happen on an otherwise normal looking leaf. This is the time most people think the tree is getting sun-scorched or salts in the soil, poor PH and no magnesium. It’s just fungus folks!

In the latter stages the leaf will start to exhibit signs of large tissue loss on the inner portions of the leaf.

Most of the damage caused by Anthracnose can be fixed with fungicide. I especially recommend daconil and copper solutions applied monthly. Keep in mind that fungicide will not cure incurred damage, just help rid the plant of future damage. The present damage will have to be removed by hand or pruning and destroyed and then treated. While not life threatening prolonged damage by fungus will weaken the plant to the point of death. It is important to treat as soon as possible to keep the pathogen from infecting other nearby plants.

Now we move on to the tree killer
Verticillium Wilt. The really bad fungus.

I am happy to say none of these pictures are mine….Thank God.

Verticillium Wilt

By Chantal Guillemin*

Verticillium spp. attack a very large host range including more than 350 species of vegetables, fruit trees, flowers, field crops, and shade or forest trees. Most vegetable species have some susceptibility, so it has a very wide host range. A list of known hosts is at the bottom of this page.

The symptoms are similar to most wilts with a few specifics to Verticillium. Wilt itself is the most common symptom, with wilting of the stem and leaves occurring due to the blockage of the xylem vascular tissues and therefore reduced water and nutrient flow. In small plants and seedlings, Verticillium can quickly kill the plant while in larger, more developed plants the severity can vary. Some times only one side of the plant will appear infected because once in the vascular tissues, the disease migrates mostly upward and not as much radically in the stem. Other symptoms include stunting, chlorosis or yellowing of the leaves, necrosis or tissue death, and defoliation. Internal vascular tissue discoloration might be visible when the stem is cut.

Once the pathogen enters the host, it makes its way to the vascular system, and specifically the xylem. The fungi can spread as hyphae through the plant, but can also spread as spores. Verticillium produce conidia on conidiophores and once conidia are released in the xylem, they can quickly colonize the plant. Conidia have been observed traveling to the top of cotton plants, 115 cm, 24 hours after initial conidia inoculation, so the spread throughout the plant can occur very quickly. Sometimes the flow of conidia will be stopped by cross sections of the xylem, and here the conidia will spawn, and the fungal hyphae can overcome the barrier, and then produce more conidia on the other side.

A heavily infected plant can succumb to the disease and die. As this occurs, the Verticillium will form its survival structures and when the plant dies, its survival structures will be where the plant falls, releasing inoculates into the environment. The survival structures will then wait for a host plant to grow nearby and will start the cycle all over again.
Besides being long-lasting in the soil, Verticillium can spread in many ways. The most common way of spreading short distances is through root to root contact within the soil. Roots in natural conditions often have small damages or openings in them that are easily colonized by Verticillium from an infected root nearby. Air borne conidia have been detected and some colonies observed, but mostly the conidia have difficulty developing above ground on healthy plants. In open channel irrigation, V. dahliae have been found in the irrigation ditches up to a mile from the infected crop.

Without fungicidal seed treatments, infected seeds are easily transported and the disease spread, and Verticillium has been observed remaining viable for at least 13 months on some seeds. Planting infected seed potatoes can also be a source of inoculum to a new field. Finally, insects have also been shown to transmit the disease. Many insects including potato leaf hopper, leaf cutter bees, and aphids have been observed transmitting conidia of Verticillium and because these insects can cause damage to the plant creating an entry for the Verticillium, they can help transmit the disease.

In Verticillium, the symptoms and effects will often only be on the lower or outer parts of plants or will be localized to only a few branches of a tree. In older plants, the infection can cause death, but often, especially with trees, the plant will be able to recover, or at least continue living with the infection. The severity of the infection plays a large role in how severe the symptoms are and how quickly they develop.

As Verticillium spreads more quickly in weaker plants, follow these sound cultural practices:

· Prune dead branches to discourage infection by other fungi. Disinfect tools between cuts in a 10 percent solution of household bleach.

· Water generously, especially during dry periods.

· Apply modest amounts of slow-release fertilizer, low in nitrogen and high in potassium.

· Mulch to maintain soil moisture, keep soil temperatures moderate and minimize chances of root injuries.

· Avoid gardening under a Japanese maple, as damage to the roots can be an entry point for Verticillium wilt.

· Don’t use wood chips from infected trees.

· Because the Verticillium fungus can survive in the soil for 10 years, do not move soil or debris from areas of known infection.

· Fungicides are not effective for control, because tree roots inevitably grow beyond the treated area.

· Seek guarantees from nurseries or suppliers that the stock you purchase is Verticillium-free. Replace severely infected trees with unsusceptible species such as yew or conifer.

Disease incidence is influenced by cultural care and environmental conditions, so homeowners who choose to beautify their gardens with Japanese maples must take precautions against the establishment and spread of Verticillium wilt.*

*Chantal Guillemin is a Contra Costa Master Gardener.
Master Gardeners
The Master Gardener programs are UC Cooperative Extension, county-based volunteer organizations dedicated to providing research-based gardening information to home gardeners. They love sharing information and answering questions.
Contra Costa Master Gardeners, 925-646-65

Susceptible plants
Maples, Most all stone fruits,(Ume) and various elms

Immune plants
Juniper, Pine, Pyracantha, Hackberry, Boxwood, Hornbeam, Oaks, Yew, Zelcova and Hawthorn

Leaves look much the same as Anthracnose, but has much more yellow in the early stages while Anthracnose goes right to brown and black.

As the infection spreads entire branches will be infected. To save the tree remove entire branch. On bonsai this is probably not a tree saving idea since removing entire branches will ruin the tree as bonsai and saving it is most likely futile.

Blackening of the trunk skin will happen and the tree may exhibit compartmentilizing trying to save itself.

The autopsy will show that the core of the tree is beginning to rot and the xylem shows a dark band.






Bonsai Tips with Justin Case ~ Summer Heat   1 comment

Summer Heat, keeping plants cool

Today is the first day of triple digits for me. This is the first day of many weeks and an endurance race to make sure the plants stay hydrated during this California drought. While the Governor has said the grass must die, container plants can be hand watered as well as watering to keep trees alive. My trees are in containers so I think I’m double protected. There is no doubt that summer heat can play havoc on any plant in a container. Since most bonsai container tend to be dark in color, they attract heat and can send soil temps into the stratosphere. Soil has a good ability at buffering away heat. Add water to that and soil temps even in triple digit heat can stay well below 80 degrees. Soil temps above 90 degrees, roots essentially stop growing. Prolonged contact with soil at this temp will eventually die. It is important to keep soil temps well below or at least 80 degrees or lower. The temperature band for optimal growth is narrow. 60 degrees seems to be the temp at which most roots wake up from Winter slumber, and 85 degrees seems to be the limit for summer soil temps without root damage. Anything above 90 degrees will shut the plant down and above 100 degrees for prolonged periods will show sign of stress like drooping leaves and shoot die back. Leaves turning Herman Munster grey green and dry and crisp is borderline death. The stems may still remain green and emergency watering may save the plant. When the leaves are brown and crispy and the bark on smooth skinned species starts to get wrinkly, death is sudden and without saving. It’s too late.

How can we protect our plants in the summer time to keep them from death?

There are many way to keep plants cool thru the summer. One of the easiest ways is to keep them watered (hydrated). For some people this may mean watering several times a day. If one has an automatic watering system this is simple to do. If one does not have a water system and one works, then auxiliary methods must be employed. There are many soil amendments that can help retain water in hot and dry conditions. The addition of clay as in the Japanese red soil, akadama is one way. This clay holds lots of moisture and gives a sort of time release to the soil container providing water vapor for most of the day.


DSC_00031 Adding a wood component to the soil mix will also add an extra measure of moisture holding properties to the soil mix. Orchid seedling mix is a good additive to the soil mix and this will also add water vapor thru the day. DSC_00360004

DSC_00370005 Transpiration not only happen on our leaves, it happens on our soil. During the hot day water vapor is released to the air until there is no more to give up. In an effort to keep this soil transpiration to a minimum, the soil surface can be covered with many water holding mediums. Wood bark is a good choice since it has many bacteria fighting properties due to its tannic acid. This keeps the formation of molds and fungus to a minimum. A good layer of fir bark will add moisture for the day. Sphagnum moss is another good medium for keeping added moisture at the top layer of the soil. It also aids in keeping fine surface roots cool and not burning off when the temps soar. I have seen people use wet towels to cover their pots and keep down transpiration. This will work but only if the towel is full contact with the soil. If air pockets between the towel and soil are there, the air in the pocket can rise to unsuitable temperatures. DSC_00280002

What about mechanical contraptions for keeping a collection cool?

Shade cloth is a simple solution for many to help shade plants from the sun during the hot part of the day. Optimum height for shade cloth is 12 feet from the plants. Most people do not want nor have the room to build a structure so tall in their yard. It will provide shade for the plant but just know that the percentage of shade stated by the manufacturer is for the 12 foot height. If you have 50 percent shade cloth 4 feet above your plants it will probably be around 75 percent shade.  There will not be enough peripheral light to give the 50 percent value. DSC_00270001 Yard trees make an excellent shade medium. make sure to set up benches, if possible, on the east side of the yard with a good tree on the west end of the yard. The hot sun in the latter part of the day will be shaded by the trees and lend the needed shade to help keep pot temps down. DSC_00350003 A misting system on a time clock may help keep plants cool in the hot part of the day. Misting is a good way to cool down a pot but some go overboard with the misting and start fungal problem with the overly moist conditions. In most climates the hottest part of the day seems to be around 3 to 5 PM in the afternoon. A one time a day misting in that time frame may be all that’s needed to help keep the pots cool. If your misting, which I do not do, spray with fungicides….Justin Case

Bonsai Tips with Justin Case ~ Early Summer Pruning   1 comment

For me I get the chance to prune many times early in the season before half the US is out from under the deep freeze. Being able to prune many times a year is not all its cracked up to be. It means that most of the year, bonsai is work rather than relaxation. I grow only a few species, the ones that thrive here. Maples, juniper, elm, hornbeam, boxwood, olives, pyracantha and pines. Unfortunately, most of these species are very hard growing, meaning that it is pruning everyday at least five or six just to keep up.

Elms are very fast growers. They will grow shoots six inches long almost daily. Yesterday I was able to prune a couple in my collection. This first one is a tree that has been beaten and battered. The pruning I do is to expose the structure and then allow the new leaves to fill in around the structure. If I am able to attend to it almost daily it will become so tight and compact that water will not penetrate the canopy.


This corkbark elm has been pruned up and is ready to grow some more. Currently I am working the canopy very slowly to build good branches and size before allowing it to fill out.


This is a kind of virtual I would like to see in a year or two.

elm virt

This pyracantha has undergone drastic pruning in an effort to reduce the canopy. All upward growing shoots have been removed and the branches have all been cut back and large stub ends reduced or removed. As soon as the buds appear, which takes about 14 days, all the rest of the leaves will be removed. The canopy will have a new look and be extremely fine and look beautiful. Sometimes you have to make them ugly to get them beautiful.


This trident maple stump has been transformed into a semi cascade. The structure is starting to get there and now I am working on finer branches to give separation between the clouds. It was recently pruned a few days ago, and now all the new leaves are coming out. These are the leaves that I now have to stay up with. A week of neglect will ruin the whole years ramification and have to start over.


Now that the new leaves have opened I can cut off those that I left on to keep the tree growing. The tree will then be only the small fine growth. this is the third pruning on the tree so this growth will be the summer growth. It will stay pretty small and the tree has stressed all I want to do until Sept when it buds again. The big leaves are about the size of a nickel and the new ones are about the size of a corn kernel.




This pyracantha was dug about two years ago March. It was reduced from a bush the size of a Volkswagon bus.


Over the last week I was able to work on the tree some more. It goes thru periods of grow out for 5 to 6 months and then I come back and cut it all off leaving the parts that add to my plan. Some new carving was done on the upper left trunk to help reduce the blunt end of the trunk that was left from collection.


Here is a virtual of where I would like to see this tree in a year or so. Just takes time to get it all filled in.


This pine was purchased from George Muranaka in 2013. The tree was started by his Father, Kanemi about 30 years ago.


Over the last two years most of the work has been just cutting out branches that will serve no purpose in the final design.




This was the last drastic removal of branches and bending that was done to the tree.


This colored photo shows the major changes in the shape of the tree. The two branches circled in red are the two current bottom branches on the tree. the large branch circled in blue was a branch removed a year ago. several other small branches have been removed.


Currently the tree looks like this as all the candles are still not all the way out. This tree will only receive small candle prunings on the right side of the tree. The rest will grow on for next year.


Continue taking pictures of your work, Justin Case.



Bonsai Tips with Justin Case ~ The Squirrel Foil   Leave a comment

This is a tip for those with maples and those pesky squirrels that like to come in a chew on bark and roots. A couple years ago the squirrels came in and chewed the entire nebari off one of my maples in 2013. I made a fence out of plastic canvas and back filled with round akadama. My roots grew back and now I am liking what I have. this is what the varmits did to the larger roots, chewed them right off.




Here is a pile of chewed off roots from that day.



Today, I began prepping the tree for display this weekend at the club show. The trunk is starting to show a more plate like fusing of the roots on the surface.


The beginnings of some flare is now visable in the lower trunk. Hard to believe that large scar on the right above the soil used to be a root. I can’t believe how much height the tree has made since removing those large roots several years ago.


There is this guy named Murphy. He shows up at my house very unexpectantly and lays down the law. His law will state that in these final few days I will be paid a vist by the squirrels in search of a snack. The roots will be gone and the tree will sit on the bench for another five years.

I took a full oversize sheet of plastic canvas and cut a slot and an over size hole in the middle. The hole is about an inch larger than the trunk. I also made a wire staple for securing the net to the soil.


I wrapped the canvas around the tree overlapping the cut ends to form  conical shape and secured it to the soil thru the holes in the canvas into the soil making sure I pierced a few roots. I didn’t want to pierce the roots, but hey, Murphy has my 6.



Bonsai Tips with Justin Case – More Damn Elm Roots   4 comments

For this entry I asked Justin Case to come up with a blog post showing how to handle elm roots for growing out of plants. I’ll let Justin take it from here;

Elm roots respond very well to root cuttings and large trees can be started straight away without waiting for trunks to fatten. Start with thick roots and save three or four years. This giant clump of elm roots came out of a cut down fifteen gallon container. It was full of huge pieces of Cali-Dama used as a drainage layer. On top of that was a good 6 inch layer of lava and smaller cali-dama. The pot and elm weighed about 85 pounds. It was a beast. The elm had grown thru some of the drainage holes and had to be cut free of the nursery can. The entire large drainage layer part of the tree had caused the roots to intertwine in between the large chunks of hard-pan.

Once the tree a free of the can, there was not much fine soil in the drainage layer. It was composed of large chunks and roots with only the small soil covering the top of the trees finer roots near the surface.


Here is a good shot of how large these pieces of hard-pan were. The size may have helped get the great movement in the roots though.




I took the ole trusty Chicken hatchet to the root ball and cut two-thirds off in two whacks.




After removal of the bottom portion of the root mass it was torn apart reserving the best parts for new plants. These were saved in a bucket of water.


Here are a few up on the table. There is enough material here to make hundreds of trees. Yea I said hundreds. A six inch long root will make four trees easy. Just cut into sections and plant. Even if they are planted upside down the shoot will come out under the soil, right itself and poke up out of the dirt in a couple of days. These things are tenacious.


I used mostly the larger roots for this project since I need more elm root cuttings like a hole in the head. I already have 8 really good shohin sized trees growing right now so making 6 to 8 trees now will be manageable. I cut away the large parts of the roots and keep the best part as the trunk.


When I get done trimming it up I throw it into a new bucket full of water.


Roots like this with neagari (exposed root) type properties will make nice penjing type trees for attaching onto rocks or to just grow out for a stand alone plant.


Heres a couple more, just showing the size of the trunks on these as a starter.




I like this one a lot. Nice short trunk, good little movement down low and already fat at about one inch+ across.


Here they are all planted up in a colander with their little heads poking out of the soil. These will be great trees in two to three years. They grow really fast since they have really good and strong root systems  and the plants are well established.




Here is what it looks like on top of the soil. This was a raffle prize donated by Glenn VanWinkle which now explains what he does with all those crappy horse turd sized nuggets of hard-pan that don’t make it thru the crusher. I think there is a cool kifu sized elm group on a turtle back type tree here. I will play with it another year and see what develops. I do know that I need to work on a few branches, since every time I prune it, which seems to be monthly, I cut everything off of it.



If you have some elm trees and with repotting around the corner, save some of the roots to plant out as new material…Justin Case.



Posted January 13, 2015 by California Bonsai Art in Bonsai Tips with Justin Case

Bonsai Tips with Justin Case – Root Cuttings   8 comments

This time of the year is very exciting for me. Repotting starts this weekend. There are also so many things to do right now before Spring gets here. Today was very sunny and dry. Almost like an early spring day. Today was 66 degrees and tomorrow the same. Now is the time to get projects started that will continue on for the next few years, and that means seeds and cuttings. It’s still a little early to start cutting here but elm root cuttings are perfect right now.

Elms are one of the plants that take extremely well from root cuttings. Especially good material can be propagated from elm roots. Elms grow long fleshy roots that actually hjave bark on them under the ground. They do not look like regular roots in that way. many times the roots will be large and twisted into bizarre shapes that translate well to bonsai culture. When repotting elms, trim away the large roots into a bucket of water and when the repotting is done, they can be cut into sections for short stubby thick trunks or left long for future bunjin trees or bent over for cascade shapes. The stubby trunks can be developed into spreading styles and brooms.

The nice thing about elms is that they will push buds from the cut end of the stub. The ring of exposed cambium will push numerous buds in a ring right out of the blunt end. Of course other buds will come after time, but the buds that come from the end should be allowed to grow and elongate to prepare the root for tree culture. Later in the year some of the buds can be pruned away, but getting the root piece strong is paramount in the first few months. In mid summer some of the growing meadium can brushed away so that the root will only grow roots at the end of the base of the stem. This will allow the plant to be put into a bonsai pot later.

All of these elms are developed from root cuttings.

DSC_00130005 DSC_000200021


Today I repotted a contorted elm. It is known as a Camperdown elm. I only cut two large roots from the tree but managed to retain some bottom roots on both and so planted them up in a pot.


These cuttings should take off in a couple months and push new leaves. Will update when that happens.

Just because the weather has been so mild I will plant out this years seeds soon. I will plant some tridents again and also some coral bark maples just to see what they do. The seeds are imbibing as we speak and will go into the ground tomorrow.


Be prepared in the winter and get ready for spring by starting some seeds and taking cuttings…Justin Case.

Bonsai Tips with Justin Case – Tool Maintenance   1 comment

Winter is a good time to keep up with maintenance on an assortment of bonsai tasks. It is a good time to spray for fungus, clean benches, break for wine,  clean pots for repotting, make soil, break for more wine and clean and sharpen tools for the new season. Cleaning and oiling of tools will keep them in good order. It is also a good time to disinfect them. A good soaking in alcohol, hexol, or dilute bleach will get rid of the critters lurking in your tools.

Why is this important?

It is important because many of the species we work on are delicate to blights, and blights can be transferred by dirty tools. Most susceptible are those of the rose family –  Pyracantha, apples, pear, quince, plum, apricot, cotoneaster and hawthorn. Fire blight is the worst and fastest growing of the blights and will destroy a plant in its entirety and is not forgiving. Cutting away damaged portions of the plant well below the blight can stop the blight but once in the plant is much like Virticillium wilt meaning that since this is bonsai, cutting away branches is not really an acceptable way to deal with the disease.

So the tools have soaked and are disease free for now. Time for a good cleaning. I use oooo steel wool. This will remove the worst of the rust and leave the metal bright and shiny. Grit blocks and fine sandpaper can be used for especially pitted and rusty areas, but one should not their tools get to this point.

If the tool needs sharpening this is the time to do it. I am not a big advocate of continual sharpening of my tools since I do not use them in such a way as that they get so dull I can’t use them. Trimming tools like shears will need the most sharpening while edge tools like concave cutters and wire cutters may never need sharpening. If one is continually sharpening a pair of concave cutters, that person may wish to invest in a good fine tooth Japanese pull saw for removal of larger branches.. I find that when a concave cutter is not cutting properly it is usually an alignment problem rather than a sharpening problem. Alignment problems stem from cutting large branches with force, springing the jaws. A couple passes with a diamond impregnated sharpening rod will restore an edge just fine. Do not use the carbide sharpeners since they work by removing a thin roll of metal from the edge. Bonsai shears are not adjustable enough to use that kind of tool very often.

Now that the tools are clean and sharp, we can continue with making them more water proof against the rust. Most iron Japanese tools come in a black finish. This is done at the factory using many salts in a hot process to build a black iron oxide coating on the iron to prevent rust. This in conjunction with a good oil will easily last a full season. I use a cold bluing kit for touching up the bluing on guns. It works well and provides an even color over the tool. With the addition of a good oil the tool looks as good as the day you bought it.

After cleaning the tools with the steel wool I had some of my tools actually resist the cold blue by beading up. Thats how good a good gun oil like Hoppe no. 9 can be. That stuff is invalauble for longevity on a tool in a really bad environment. Tool treated with WD40 or three in one oil will not hold up over the long haul. I have heard that Marvel Mystery Oil is also very good for keeping tools oiled over a long period of time. When the tools resist the blueing just wipe them down with more solvent and try again.

After oiling I roll mine up in newspaper and then a cloth and place them in my bag till I need them for repotting and the rest of the season. Keep them dry and out of moisture….Justin Case

This is a pic of the items used to clean , blue and oil the tools.


This is a close-up of the cold gun blue. This product has been around for a long time. I have had this bottle for thirty years. It is almost gone, about 1/4 inch left in the bottle. I think I got my monies worth.

Here are the tools before the cleaning and oiling.


Here is a pair of shears with most of the blue worn off from use. Japanese tools with heat applied blueing from salts will only require touch-up, while iron tools like these Corona’s that were never factory blued will wear off in a season.

Here they are after the cold blue is applied. It does a great job and once oiled it will last several years. I do mine about every other year. They didn’t get much use last year with the stones and cancer in the family. This year I hope to see the tools all silver by Fall.




Here is some superficial rust that will grow in the places hands can’t keep it buffed off. Keeping up with oil after use will cut down on this type of rust.





This type of rust is bad. This rust is pitting the metal and actually degrading the iron to the point of leaving a depression. Shame on me for allowing it to get this bad.

Here is a pair of leaf shears. This is factory blue, but use has actually removed the blue to almost bare metal. Not much rust here, just needs cleaning, disinfecting, and a touch up blueing.


Here is just the top handle blued so one can see the difference.

Below are some more examples of before and afters of the blue process.



The tools are now all cleaned up and ready to be packed away until I need them. I will wrap them in newspaper and then a towel and keep them in my bag until needed. Once I have used them I will clean and oil them before putting away. They will last a lifetime if cared for properly. Many of these tools are thirty + years old and still cut like the day I bought them. Most of my older tools are Kiku, which made very fine Ikabana and Bonsai tools in the Fifties thru Eighties. They are hard to find now.



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