Root over Rock tridents – 1 year on

In the last Shibui Bonsai post I showed how I start root over rock trident maples. They are then planted in large pots or boxes in the nursery for the summer. I find the nursery is the best place because the trees get regular water that can trickle down between the rock and foil and keep any of those shorter roots alive until they grow long enough to reach out the bottom and into the potting mix.

I generally leave these trees untouched for the entire summer. More growth up top means more root growth below soil level and that’s exactly what I want.

Here are a couple of the root over rock trees I started last year.

This is the part I really look forward to. These trees have been growing all year but we can’t see what is developing below the soil. Will the results be great, OK or terrible?

A good spread of roots all over the rock
Strong roots with good placement
Another nice set of roots with a well placed trunk

At this stage, after just a year of growth, it is still possible to move some roots if necessary to improve the look. You can see that in many cases, new white roots have started to grow down the rock. In some cases I’ll remove some roots if it looks like there are too many. I want to see that there is a rock in amongst those roots. Too many and, as the roots thicken, the rock will be completely covered.

Now the trees are wrapped again with fresh foil and planted for another year of growth and thickening. All of these had plenty of roots from the bottom of the foil so could go into the grow beds for maximum growth. If few roots have extended to reach the bottom of the rock I’ll put those back into the nursery for another year of intensive watering.

New root over rock tridents

Spring is rapidly approaching at Shibui bonsai nursery. Some of the Chinese elms already have tiny green shoots opening so the trident maples can’t be far away from starting to grow too. That means I need to get on with any jobs that involve root work.

Making new root over rock plantings is one of those jobs, so this week I emptied out a polystyrene box of last year’s trident seedlings to select some candidates for new root over rock plantings.

Raw seedlings rarely have enough roots to wrap over the rocks so I prepare for root over rock plantings a year ahead. I take one year old seedlings and cut the thickest root so the seedling now has just a couple of lateral roots then plant it into a deeper container to grow for another year. Because I do a few of these each year and because it is good to have some choice to get the best match af tree and rock I usually put a few trees into the box.

raw seedling before root pruning
after cutting the long roots

With some care and a little luck I end up with a bunch of seedlings with lots of long roots. Perfect for starting root over rock bonsai.

There will probably also be some that are not so good. This one has one really thick root that will make it quite difficult to sit properly on the rock.

I can prune those roots back hard and plant that one as a normal starter tree.

Now I need to look at the rocks. Not all rocks are good for Root over Rock bonsai. The best rocks have some character – peaks, hollows and shoulders. Avoid rocks that are likely to weather and break up as they age. No point putting time and effort into a root over rock arrangement if the rock falls apart before the tree matures!

Look at the rock from all sides to identify the best aspects and shape. Rocks can be upright like a mountainside or horizontal. Find some spots where the tree will sit well and roots will look good running down the surface. It will help the matching process if you have several rocks and a number of trees. Often the shape of the trunk and roots means a tree just won’t sit well on a particular rock but another tree may just be the right sahpe for that one. Soak the rocks in a tub of water. Dry rocks will suck any moisture out of the fine roots as you arrange them on the rock.

Now to match the tree and rock. Aesthetically, the rock will provide the visual weight for the composition. That’s where the viewer’s eye will start, then follow along the rock and on through the trunk of the tree so it is important to have good angles and visual flow where the trunk sits on the rock. Roots flowing along the same lines rather than across will also help the design.

Try a few trees in a few positions on the rock looking for the best arrangement. At this stage I’m really only looking at the angle between the rock and the first section of the trunk. It may help to try to imagine a future canopy above the rock. Will the tree and rock harmonise or compete? Do the roots allow the base of the tree to sit well at the desired angle on the rock? Sometimes just cutting 1 or 2 roots will allow the tree to sit better.

Now arrange the long roots over the surfaces of the rock. It is important to have roots right round the rock. Some down the front and some down the back so as they grow they will really hug the rock tight. At this stage try to avoid straight root runs which don’t look good when the roots have thickened. Roots that twist and meander over the rock following crevices and hollows look more natural and interesting. Bear in mind the visual flow of the rock and try to arrange roots to enhance the flow rather than cross it.

Prepare a length of aluminium foil. It needs to be long enough to wrap around the rock 2 or 3 times. Unless you have selected a really tall rock the foil will be way too wide. For most of my rocks I fold the foil in half lengthwise but for taller rocks you may just need to fold 1/4 or 1/3 down so that the lenght of foil is now as wide as the root part of your rock is tall.

The next part may require some practice or another pair of hands. Sit the tree in place and position the roots on one side of the rock while laying it onto the foil. Cradle the foil and rock in one hand. The weight of the rock should now hold thos eroots in place. use your free hand to position the next roots and fold the foil over to secure them. Continue to position roots and trap them in place as you roll the foil round the rock until you wrap right round the rock. Make sure the foil is pressed into all hollows as you go so that roots are pressed right up against all surfaces of the rock. Continue to wrap the foil round and round until you have 3 or 4 thicknesses holding the roots in place.

Don’t worry if there are no roots showing out the bottom opening. Water can run in the top to keep the roots alive. sooner or later they will grow long enough to appear at the bottom of the rock. The beauty of the foil is that any new roots must grow right along the surface of the rock which is ideal for root over rock style bonsai.

Pour some water into the top opening to make sure the roots are still damp then plant the foil covered rock into a deep container and fill it with potting mix right up to the top of the foil. The pressure of soil against the foil will help press the roots closer to the rock as they grow.

New root over rock trees planted in a polystyrene box

Feed and water well all through the growing season and allow the top to grow freely to maximise root development.

Repotting season is here.

It is still officially winter here at Shibui Bonsai but a few warmer nights has stimulated some buds to start growing so I’ve been stimulated to get on with the repotting.

Yesterday I root pruned and repotted all the small shohin sized bonsai. I’ve found that these little ones do better if they are repotted every year. The roots grow fast enough to completely fill a tiny pot in just one summer so the following year it becomes difficult for water and air to penetrate into the root zone and the trees start to suffer.

Look how tight the new roots are on this one

After pruning the roots there is now room for more roots to grow this summer.

Here’s another shohin sized trident maple. Again, the pot is crammed with roots so I need to remove some to make room for the new roots this summer.

I root prune these little ones just like the larger trees. First cut around the edge of the root ball to remove all the matted new roots that are circling the pot.

Then slice off the mat of roots underneath.

Followed by a rake out of the remaining root ball if needed and maybe sip off any more longer roots. then the tree can go back into the original pot with some fresh potting mix to fill the spaces and give somewhere for new roots to grow.

Developing better nebari

Starting seedlings through holes in metal plates is not the only way to grow good nebari. I also grow many trees just by regular root pruning to control and direct root growth. Here are some photos to show that method.

Seedling before

Most seedlings develop a strong vertical root to ensure the little tree has access to deeper damp soil so it can survive a dry summer. In bonsai we don’t want deep roots we prefer to see well spread strong lateral surface roots. First step is to cut the vertical root. I usually look for a spot where there are several lateral roots around the trunk and cut just below.

Often I need to also remove any single higher roots. If I leave those to grow they tend to grow faster and create lopsided root system. The remaining lateral roots don’t have to be right opposite. In fact it can be better if roots on one side are higher so the seedling can be planted at an angle with remaining roots horizontal. Initial leaning trunk tends to yield a better informal upright tree.

Another seedling before
and after pruning roots

I also cut the trunk shorter to help push multiple leaders the following summer. Multiple leaders give me better options for bends in the trunk and better taper.

These trimmed seedlings are then potted into pots for a year’s growth. After a year I should end up with something like this small trident. Note that this is not the same tree as above but it is representative of tridents after initial root pruning as shown above.

In the second winter the roots are trimmed again. Note how well the tree has responded to the previous radical root pruning with a mass of lateral roots around the area I cut last winter.

roots after trimming a second time
Again, down growing roots are eliminated

At this stage the tree can go back into a grow pot for controlled development or into the ground for faster growth. The following tree was started using this root pruning technique followed by 2 years in the grow beds. Tridents in the grow beds are dug and root pruned every winter at Shibui Bonsai

More field grown trident maples

In the last post I showed a couple of the trident maples I’m currently digging and pruning.

You may have noticed the very horizontal root spread.

These tridents have been developed using the ‘plate’ method.

Start with a piece of metal sheet with a hole drilled through the middle.

Mine have been cut from old aluminium roadsigns I bought at the scrap metal yard but any sheet metal will do. Some growers use wall or floor tiles but they can be difficult to drill and I found that growing trident roots exert enormous pressure and broke the tiles. CDs are also crushed by growing roots but I’ve used these pieces over and over for nearly 10 years now with excellent results.

I start with seedlings. Thread a seedling through the hole.

Don’t go too far through. if any roots are above the metal one usually grows far quicker and gives an unbalanced root structure.

Note that I’ve placed the trunk on an angle through the sheet. If you want a vertical trunk stand yours upright but make the choice now because next year it will be too late to make changes.

Plant the tree with its metal collar about 1cm under the soil. Too deep an you’re likely to get more roots than you need and they may not be evenly spread.

As the trunks grow fatter the metal starts to cut off circulation in the tree. The tree responds  by producing callus and then new roots just above the restricted area. The only option for those new roots is to grow out over the metal in a flat plane. Eventually circulation to the roots under the metal is completely cut off and those roots will die off leaving your tree with a new, flat root system.

I find it far better to keep these trees in pots in the nursery for the first year. In the ground, new roots are forming just as the heat of summer hits and if they don’t make it over the plate and down into deeper soil there is a risk that they may dry out on hot days. Daily watering ensures they will grow and survive until, after a year, the tree looks something like this

Here’s a closer shot of the new roots above the metal plate.

Now those new roots above the metal are pruned quite short.

Then the tree can be planted back into a grow pot or into the ground to thicken up. remember not to plant too deep. Tridents love to grow new roots right near the surface so if these roots are buried deep the tree will grow new ones that may not be as good.

Another year of growth and I now have a thickened trident with developing horizontal nebari. A side benefit is that the base of the trunks tends to swell and buttress far more than with other techniques. You can see that there’s no real advantage in using larger plates. To get good root ramification the roots need to be pruned quite short each year and larger sheets just make it harder for the new roots to reach moisture deeper in the soil.

Another year or 2 and I have the sort of tree shown at the start of this post.

I find that threading trident seedlings is an easy way to produce superior root spread on trident maples but I have also used the same technique on Japanese maples and even on Japanese black pines. It should work with most tree species and I’d be interested to hear from growers who have used it on other trees.

Field grown trident maples

At Shibui Bonsai I have finished digging the new root over rock trees so it is time to get on with the rest of the trident maples.

here’s one of the tridents I dug up this week.

It seems that I use a few different techniques when growing trees in the ground for bonsai

Let’s focus on the roots for a start. I dig most deciduous trees every winter and prune the roots. I know that many other growers claim this slows down development and maybe it does but the little I lose, if any, in size is more than made up for in nebari.

Just so it is easier to see, I’ve washed the roots in water and done a rough trim.

Last year the roots were cut very short – about 2cm from the trunk. You can now see the result. Lots of new, white roots have grown from the cut ends. These new roots will thicken and gradually merge together to form the characteristic plate like nebari in coming years. Those new roots will now be cut short again, probably 1/2 cm this time and, of course, each one will grow a number of new roots again. Just as branch ramification is valued above ground, Root ramification below ground should be the aim of good bonsai growers.

Now both roots and branches have been shortened ready to go back into the ground or into a pot for further development.

Here’s another trident maple after trimming both roots and branches.

You may note that I’ve left a few extra leaders on both these trees. I remove any that I think are growing in the wrong direction or in poor positions but I generally leave several possible new possible leaders as insurance. When the tree is growing well next summer I can make final decisions about which trunk line to follow and the others will be pruned then.

Root over Rock tridents

Winter is a great time of year at Shibui Bonsai. I get to dig up the trees in the grow beds and see what has been achieved over the past year or 2.

The root over rock tridents are the most exciting because I can’t even get a glimpse of the rock/root arrangement until I dig them and unwrap the rock. It is almost like opening Christmas presents. You never know what you’ll find.

Here’s the row of ROR. Rock and roots wrapped in alfoil and buried.
Here’s one still wrapped up

Tear off the foil to find out how well those roots have grown and grabbed the rock.

The best ROR have roots that wrap right round and hold the rock tight. Roots should be growing in close contact with the rock. Like they grew there naturally.

In this case, both sides look really attractive. that will give more options for styling the tree later.

At this stage the top is just cut back and only obviously unusable branches are removed completely. I’ve left several possible new leaders to see which looks better when they grow next summer.

Here are a couple more that I dug and pruned today.

one side
and the other

Actually, the tree above got a bit carried away. I was aiming for a nice small tree on a small rock – obviously the tree had other ideas and now I’ll have to develop a larger trident on a small rock..

And here’s another one. Plenty of well placed roots holding tight to the rock. A great start to another new Root over Rock trident maple.

Something I don’t look forward to seeing is roots growing through the foil.

Trident maples seem to love growing lateral surface roots. Much more than most other species and if one grows too strong it is likely that the roots closer to the rock will not grow as well. Removing large wayward roots also leaves unsightly scars on the visible roots. one reason for the foil wrap is to keep those roots growing close to the rock.

Fortunately, this escapee has not affected the roots inside the foil yet so when it is cut off the tree is still usable.

A few hours work and I have a small treasure trove of new pre bonsai Root over Rock tridents. They will be left buried here until I’m ready to pot them into individual grow pots to recover and begin the next stage of development.

If you have not seen the beginning of this process to develop root over rock bonsai using aluminium foil here’s a link to a previous post showing the earlier steps.

Developing small tridents – another approach

In an earlier post I mentioned that there is never just one way to grow bonsai. There are many different approaches that I use. In this post I’m hoping to present several different options for a tree like this. All of the different options would yield good bonsai. there’s never a single ‘right’ way to bonsai.

Here is another small, pot grown trident maple with lots of different possibilities.

Some beginners would be happy just to put a tree like this straight into a bonsai pot and call it bonsai. It has a trunk and some branches and it does look quite tree like but I can see future possibilities.

First step is always to check the roots. Visible surface roots (nebari) is very important in bonsai, especially in maple bonsai. Visible roots is  a sign of age and stability. As trees grow the roots also expand so eventually the roots just under the surface start to get thick enough to show through the ground near the trunk. When we see this our mind knows that must be an old tree. Roots spreading in all directions give us the impression of stability and permanence so good surface roots helps make an impressive bonsai.

There is a good spread of larger roots there because this tree has already had its roots pruned a couple of times in past years to help form a spreading root system. You may also be able to see some thinner new roots that have grown this past season. They are a little higher than the older roots and mostly on one side of the trunk. If I wanted to lean this trunk over a bit further some of those new, higher roots would be great but I think the current trunk angle is good so I’m going to cut them off and use the existing thicker roots for the nebari on this one. The size, spread and angle of the surface roots is an important factor in deciding how to shape a tree. always check where the roots are and what the look like before starting on design.

 after cutting the higher roots

Now we know the roots are Ok let’s check the top.

There are 3 strong, vertical leaders on this trunk. Maybe if I wanted to design a broom style tree I could keep several sub-trunks growing from the same place but leaving more than one growing close together will almost certainly lead to the trunk thickening significantly where they join. I try to remove multiples as soon as possible to keep good flowing taper.

after removing spare sub-trunks

That’s better but the tree now looks very tall and skinny. There’s lots of straight sections which seems a bit boring and there’s very little taper in the trunk. Taper is another important feature to give the impression of an older tree. Young trees grow up quickly to try to reach full height ahead of any competitors. At that stage they are tall and skinny and we recognise them as younger trees. As trees age the trunk becomes fatter but height doesn’t increase much and we tend to recognise that fatter trunks are older trees. In bonsai, we have several options to show viewers thick, old trunks. We can put the tree aside until it does have a thick trunk but we can also change the perspective. A shorter tree with the same sized trunk appears to be fatter than the same tree tall. I’m going to shorten this trident to give it the appearance of thicker trunk.

I usually look for a side branch to cut back to when pruning trees for bonsai. Here’s one option. Note that I’ve chosen a branch that’s growing back toward the base of the tree so I can eventually form more attractive bends in the trunk. This spot also gives me a side branch to start working with. What may seem to be a step backward is actually a bonsai step forward in the future development of this tree.

Although the new tree does look a little thicker with that reduction in height I’m still not happy with the result so I’m going to cut lower again.

Another temporary bonsai step backward in an attempt to give this tree a better future. This would be a fine spot to stop for now. Wiring that side branch up to become the new trunk gives me a really nice first curve to the future trunk. The step down in size gives the tree far better taper. Taper is another important aspect in simulating older looking trees. As trees age the lower parts tend to thicken far more than the upper parts so we see older trees with thicker trunks and thinner upper branches – taper. There is probably also an element of perspective involved. When we are at ground level, the trunk is close so it appears larger while upper branches are further away and therefore appear thinner due to perspective. Bonsai with good taper definitely appear to be older. Smoother transition from thicker to thin also helps our eyes travel up the trunk when viewing a tree so we try to avoid bulges and reverse taper in bonsai to enhance our view of the trunk and branches.

You might have noticed that I don’t have a desirable branch at that new bend in the trunk. Why didn’t I just chop the main trunk out and leave the new leader and the side branch? Whenever I’ve tried that the results are far from pleasing. The trunk appears to be a thick stump at the cut site. The problem just seems to get worse as the tree continues to grow and thicken. I’ve found this sort of angled cut a far better alternative. But what about a side branch at that bend? Even though there’s nothing there at the moment I know trident maples well enough to be confident that a number of new buds will grow near that cut. One of them will surely give me the branch I need. Another step back to set the stage for a better future.

However, I’m not finished with this tree yet. this option is Ok. It has reasonable taper and a good bend about 10 cm above the roots. With the oft quoted scale of the first branch about 1/3 of the at up a tree to look balance this little tree would probably grow into a really nice 30-40 cm tall bonsai. If that was my aim I’d put this tree aside now, pot it up into a larger pot and allow it to grow freely for another year to increase the trunk thickness.

That lower sub trunk has given me another option for this tree. I can see another step backward that will possibly give me an even better, smaller bonsai some time in the years to come.

This cut has given me even more powerful taper and a bend just 3cm above the roots. With this I will be able to develop a shohin sized bonsai 10-20 cm tall with excellent taper and good trunk bends. As a bonus, the new leader is already heading in the right direction so there’s no need to wire it at this stage. note that I’ve pruned back the new leader to where there’s a couple of sets of buds on short internodes. Short internodes are even more vital for smaller sized bonsai so I always remove shoots with long internodes and develop my trees from shoots and branches with short internodes. The shorter the better.

This tree will be root pruned quite hard this winter or spring to further enhance those surface roots and given fresh potting mix to accelerate growth next summer. A larger pot would give increased growth but there’s a chance of it growing too much and losing the current good points. Slower development takes longer but usually gives me superior results in the end.

Developing tridents: the next phase

Another year or 2 should see some trunks with both taper and attractive bends. Maybe they even have some shoots in the right places for branching.

Take a closer look at some of the issues that need dealing with.

The first branch has died back a bit and the remaining shoots are crowded and growing at awkward angles. Maybe it would be possible to wire these and bend them into acceptable positions but the outer ones look a bit rigid to me so I’m just going to prune back to a thinner part that I can bend with wire. Pruning also puts valuable taper and good bends into the branch.

Further up the trunk there are 2 upright branches, both trying to be the apex of this tree. there are also those strong upright new shoots that grew last summer. Note the long internodes.

Either of the leaders could give a good overall tree shape but I’ll keep the longest one to give the tree more movement.

Those long internodes are no use on a small bonsai. remove all shoots with long internodes completely if you don’t need a branch in that place or back to the base if you would like a branch there. Fingers crossed that the next shoots to grow will not be quite so vigorous. This time I am lucky. there are already smaller shoots with shorter internodes growing below those big vertical ones. just right as the basis for a future branch so I’ve pruned the strong vertical ones off completely. (see final photo)

There are more shoots with long internodes toward the top of the tree. (blue lines) New shoots can only ever grow from the nodes so If I try to make branches out of these shoots they won’t have many side shoots. Remove all long internodes, even if you do want a branch at that point.

Now on to the apex.

I’ve removed the right shoot at the top mainly because I think movement to the left looks better. the left shoot is also a bit thinner so taper is enhanced.

A little wiring has been used this time to help position the remaining branches. A couple have been bent down closer to horizontal and others have been rotated so the smaller twigs are now horizontal as the basis for future branch ‘pads’

Developing young tridents further

This time the trees are another year older. You may find starter stock like these in the bonsai section of nurseries. If you are intending to grow larger bonsai or really fat trunks your trees should be planted in the ground or large grow pots by now. I’m aiming at smaller sized bonsai with these. At this stage the possibilities start to magnify and different growers will take different routs to produce bonsai from this point.

This one has reasonably attractive bends in the trunk and a few small branches to choose from. Some beginners would be happy to put a tree like this straight into a bonsai pot. That’s fine if you want to but I can see plenty of improvements I’d like to make for the long term future of this as bonsai.

First I’m checking the surface roots. Nebari, or visible surface roots, is really important to show age and stability in a maple bonsai. I want to have good, strong roots evenly spread all round the trunk if possible.

The roots are a little lower on one side. If I tilt this tree a bit the current roots will all be level – a far better view. Fortunately this tilt helps bring the top of the tree above the base and actually improves the flow of the trunk.

There is very little taper in this tree. A good maple bonsai is much thicker at the base and tapers gradually right through to the top of the tree. Pruning is the quickest way to introduce taper into your bonsai, removing thicker parts and keeping thinner sections as new leaders. The section marked in blue below is also very straight so doesn’t fit well with the curves in the lower trunk.

Pruning away the problems will leave me with a far better skeleton.

I’ve removed that straight section completely to continue the curves then cut out the top of the tree at a convenient smaller side branch which will now become the new leader giving the tree some more bends as well as taper almost instantly. Now that the tree is shorter it also appears to be much thicker.

I’ve also decided to wire those 2 branches now while they are still flexible enough to bend easily. There’s still a few years of growing and development ahead. the extra, unwired branches are probably not part of the final design but won’t hurt in the short term and will probably even help the trunk to thicken a bit more. I’m also hoping for some more shoots to pop out of the trunk next spring after removing this much from the top of the tree. maybe some of those new shoots will be in good places to add more branches to the tree.