Soil | Bonsai South

Chinese Elm Repotting – Key Bonsai Practice

by Zach Smith | Feb 3, 2020 | Care, Chinese Elm, Elms, Potting, Pruning, Soil, Watering

Repotting our trees is a key bonsai practice, and one that you must gain mastery of. Here is a summary of basic steps you’ll take each time you repot your trees:

Make sure you have all necessary tools and supplies, including prepared soil, before you start
Have a suitable space to work in – outdoors a bench is ideal, indoors a small bench or table and a large tub to work in will help keep the mess contained
Prepare the new pot if you’re changing pots; if not, you’ll need to thoroughly clean the existing pot, replace drainage screen and the tiedown(s)
Unpot the tree and inspect the root mass
Comb out the roots which will have coiled their way around the outer edges of the mass
Trim away the overlong roots and enough of the root mass to give room for fresh roots to grow
Make needed corrections to the roots, namely the exposed nebari roots that are part of your design
Add fresh soil to the pot to provide a thin bottom layer – slightly heaped in the middle
Place the tree in the pot
Tie the tree down once you’re satisfied with the placement
Fill in all around the tree and any spaces in the root mass; use a chopstick or other tool to work the soil in
Water thoroughly; allow to drain; water thoroughly a second time; newly potted or repotted trees with fresh soil will need to be watered more frequently than others, as it take a while for the fresh soil to become properly wetted
Fertilize (this is optional at this time, but I tend to forget as I move on to other trees, so I go ahead and do it at the time of repotting)
Place moss on the surface if so desired.

This is today’s subject, the Chinese elm that has its own Progression page.

It was last repotted in 2018, and though it could probably go another year without it, there are a couple of issues with the nebari that I want to correct before they get out of hand.

This is one of the roots that I’m unhappy with. Though it’s grown well and is about healed from the previous pruning I did, it’s just too straight and untapering a surface root to remain. I can solve this problem as part of the repotting process.

This one’s a little harder to see, but the surface root at the left has a smaller root coming off it that runs at an angle back toward the base of the tree. It’s also too long without taper and needs pruning back.

Step number one, the tree is pulled from the pot. It’s at this point that you do the assessment of the root mass. Look for any root rot caused by poorly draining soil. Always cut away any dead roots – you can’t eliminate all the fungal pathogens by doing this, but removing the dead roots and using free-draining soil when you repot will allow the tree to recover on its own (which it should do). Expect to see fresh white feeder roots when you inspect the root mass. This is a good sign, of course. Don’t worry about trimming these off as a necessary part of pruning the roots to make the mass more compact; the tree will happily grow new ones.

I combed out the root mass, trimmed away some of the excess roots, and washed off the excess soil that I’ll be replacing. It’s easier to see root problems once you get to this stage. In this case, it’s a root that’s coiling back toward the trunk base. These should either be removed entirely, or if you need a root that’s grown this way then gently uncoil and trim it so it grows in the desired direction.

Here I’ve pruned that first of my large offending surface roots. I’ve also removed the coiling root that I don’t need since I have a good mass of roots to support the tree.

In this photo you can see that I’ve pruned back the large root even more. My goal is to build the taper of this surface root. By pruning it back, I can expect the roots already branching off this one to continue to thicken over time. That should produce the effect I want.

Here’s the view from the other spot where I have that odd root moving back toward the trunk. There’s obviously work that needs doing.

The offending root is gone, and I’ve pruned back the too-straight surface root as I did the other one. I’ll be able to build taper with this one as well.

Here’s the tree after the final root trim. I’ve removed about a third of the total root mass, which is the right amount for this repotting. The amount of root mass you remove will vary based on how long it’s been since the last repotting, and how much root the tree has grown in the interim. With experience you’ll be able to immediately gauge this as soon as you pull the tree from the pot.

Here I’ve placed the tree back in its pot. I previously washed the pot thoroughly, made sure the drain screens were in good shape, and replaced the tiedown wire.

Placing your tree in its bonsai pot requires you to consider several parameters to ensure the composition is its best. They are (in no particular order):

Determine the correct placement of the trunk base – in this case, since my tree emerges straight from the soil and terminates left of center at the apex, the base needs to sit slightly toward the right side of the (oval) pot
The tree also needs to sit slightly to the rear of the pot
The tree sits on a slightly heaped mound of soil, which brings the base just above the rim of the pot
I had previously selected this pot because it is, in profile, roughly as deep as the trunk base is wide
The pot measures about one-half the height of the tree in length, making for a good proportion
The initial portion of the trunk emerges straight from the soil; the planting angle needs to be such that the initial portion of the trunk is perpendicular to the pot rim.

The tree has been tied down (I use a single tiedown for most of my bonsai; use however many work best for you), and the pot filled with soil. This step requires a lot of care. You can’t leave any gaps beneath the surface of the soil, because that spot will dry out and any roots there will die. Most everyone uses a chopstick to work the soil into and around the root mass. Some will say never to jab the chopstick into the root zone when you do this; I’ve never found this to cause a problem, since there really aren’t that many tender roots present at this stage of the process. If you’re concerned, then you can carefully insert your chopstick and wiggle it back and forth to work the soil in.

Here’s a closer look at the nebari. I’ve improved the surface rootage quite a bit, and this should result in a much better bonsai in a fairly short time. This tree has been in training since 2014, so the next few years should complete the making of this Chinese elm bonsai.

The final presentation for today. I did a little trimming of the branches (there’s probably a little more to be done), then watered and placed some moss on the surface. I also added some time-release fertilizer so I don’t get busy with other trees and forget. Because I’ve done root work on this tree today, it’s probably going to start opening buds within the next week. I have a lot of small Chinese elms in gallon pots, and most of them area already leafing out. Spring is getting closer by the day!

Let me know what you think of this repotting job.

Layering To Improve Trunk Base And Rootage – Privet

by Zach Smith | Nov 2, 2019 | Care, Privet, Soil

It’s not uncommon to have a less than stellar base or rootage on your bonsai. This Chinese privet, Ligustrum sinense, is a good example. The tree is nice, for sure, and will be just about fully developed next year after a good start this year, but there’s an issue at the base in front that just doesn’t add to the tree’s appearance. In situations like this you’ve got a couple of choices: carve until it looks better or “work around” the objectionable area.

Privets don’t lend themselves to carving, especially low on the trunk, as the wood has a tendency to get punky and rot out after a few years. If you do utilize carving on a Privet specimen, be sure to have some PC Petrifier wood hardener on hand. You’ll need it sooner rather than later.

So in the case of this tree, I’ll need to “work around” the problem at the base. And what better way than to layer the tree?

Once you’ve figured out where you want the new roots to emerge from the trunk, you’ll need to carve a band of bark and cambium all the way around. It’s vital to take the cambium with the bark, otherwise the tree will only produce callus tissue over the wounded area and you won’t get the roots you want.

The view from the other side. I made the band pretty wide, and you don’t want to learn the hard way why this is done. Callus tissue will form at the top of the band. If the band is too narrow, the callus will bridge it and simply heal the wound you made, in preference to producing roots from the area.

After dusting the top of the stripped area with rooting powder, I used this high-tech method of making a “pot” for my new roots to occupy. It’s literally a nursery pot that’s had the bottom cut out, been cut to wrap around the trunk, and bound with good old duct tape. There’s nothing like simplicity!

The makeshift “pot” is filled with soil and watered. All I need to do now is wait.

You’re probably wondering if this is a good time of year to do this work. For most species the answer would be no. Privet is semi-deciduous down South, so there will be active root growth through much of the winter. If I’m lucky, by the time spring gets kicked off next year it won’t take long to produce enough roots to allow me to separate the layer. I’ll update when that happens.

Bonsai Odd & Ends: Making Soil & Potting Water-Elm #40

by Zach Smith | Mar 10, 2019 | Care, Elms, Potting, Soil, Water Elm

I’m often asked about the soil I use for my bonsai. Here’s a short blog about how I do it. There are countless formulas for bonsai soil, and the subject is one of the most hotly debated out there. My advice: find out what works for you. Here’s what works for me, and how I go about making it.

First things first. A bonsai soil must do a few things well. Here’s the short list:

Water retentive (the roots need water)
Aeratible (can help provide adequate air pockets; the roots must have air)
Free-draining (the water must not pool on the soil surface when you water – if it isn’t gone in one-Mississippi, you’ve got problems)
Not weigh a ton (there’s a limit to how light you can make your soil, and how light you should make it)

The photo at left is the larger-mesh of the two screens I use when making bonsai soil. Simple construction: a 1 x 4 x 8 cut into four equal lengths, assembled with deck screws. A piece of 1/4″ hardware cloth cut to fit and nailed to the underside with staples.

The smaller mesh screen. This one utilizes 1/16″ window screen. So that gives you an idea of the particle size soil I’m after. I use the larger-mesh screen to remove the chunks bigger than 1/4″, and the smaller one to remove the “debris” smaller than 1/16″ (which is sure to contribute to packing of the soil and water-logging plus anoxia for the roots).

If you make your own screens, the small-mesh screen needs to have a trim strip covering the window screen. If you don’t do this, it’ll rip away when you overload it with soil components.

Component 1: pine bark mulch. I buy it in bags from Home Depot. You can make a lot of bonsai soil with one bag of this stuff.

Here I’ve stacked the two screen, large mesh on top of small mesh. In goes a slug of pine bark mulch. It’s gotten wet from all the rain we’ve had lately, so I need to get it dried out.

Spread out on a nice warm day. It’ll dry pretty quickly. Then I lift the top screen and shake out some of the good stuff onto the bottom screen.

Here’s the good stuff, what stays on the small-mesh screen. I pick out any long but narrow pieces, spread it to dry, then shake it until I don’t see any significant small stuff coming through the bottom.

Component 2: Riverlite expanded clay lightweight aggregate. I use a 3/16″ coarse grade. I don’t know of anywhere you can buy this material in small quantities (I don’t sell it, so please no inquiries). You can use Turface(TM) as a substitute. I have used their All Sport(TM) product in the past. If you have a local landscape or sports park supply shop they should have it.

This is still wet from the rain, too, so I spread it out to let it dry.

Dried and ready to have the fines shaken out. This and the pine bark are mixed roughly 50:50.

The final product.

Water-elm #40 is starting to push buds now, so today was an ideal time to put it in a bonsai pot. Am I rushing things? Since I don’t have a lot of work to do in creating a tapering transition in the apex, the branch development work will go quickly even though the tree will now be in a bonsai pot. I know the tree is well-rooted, so the risk is low.

I’ve had this beautiful Chuck Iker pot for several years now. It was one of his first successful pieces sporting this particular glaze, which he calls “ancient jasper.” The color matches the new growth on a Water-elm very nicely.

The tree placed in the pot, and tied down.

And the soil all packed in tight. This tree should be in full leaf in about two weeks. Our weather had warmed up a few weeks ago, but then we had a cold snap that set many trees back a bit. Now it’s warmed up again, and I don’t think we have more than a few cool nights left this season.

I’ll post updates on this tree as it develops this year.

Let me know what you think of this composition. The pot may be a bit heavy for the specimen, but I’ll know better once I get some branch development.

Crape Myrtle Repotting

by Zach Smith | Feb 17, 2019 | Care, Crape myrtle, Potting, Soil, ZPC

It’s been two years ago that this Crape myrtle, Lagerstoemia indica, got a new pot and some much-needed design work. The tree has been happily growing (and blooming in summer) in its Byron Myrick custom pot. But as with all bonsai, sooner or later you’ve got to repot. Crape myrtles in particular are going to need this to be done more frequently than most species. Why? They grow roots more vigorously than just about any other species. So in order to keep them healthy, they need attention every couple of years.

But first, the tree has gotten rangy on me and it’s got to be taken back in. This is one of those chores that many bonsai enthusiasts either fail to do or don’t do to the degree it’s needed. For those of you who’ve been at it for a long time, you know what I mean! It’s hard to make yourself prune back hard. But it must be done.

Next step: pull the tree from the pot. You can see how successful this Crape has been in filling its pot. We’ve got the telltale circling roots. They grow to the edge of the pot, then they circle. Happens every time, which is another reason we have to root-prune periodically.

Notice the new white roots that are growing. This means the tree is going to be pushing buds very soon.

How much root should you take off? I like to remove roughly half the volume of root. Here’s what that looks like.

Another view. In addition to removing root around the edges of the mass, I’ve also removed some from beneath. The tree also needs some fresh soil in the bottom of the pot.

I cleaned the pot and replaced the drain hole screens, then put a layer of fresh soil in the bottom.

Now the tree is placed in the pot. You may notice that I’ve turned the tree slightly. This helps fill a gap between the first right-hand branch and the apex, which I actually created by pruning a sub-branch off the first left-hand branch that had been used to fill in behind the tree. I decided this branch looked funny and needed to go.

I’ll come back and wire that right-side branch (which I had coaxed from a bud this past year), then pull it down and into position.

The tree placed on top of the layer of soil I put in the pot. I’ve made sure it sits at the proper level in the pot.

The final step of the repotting, filling in with soil.

I like the tree with this front, so until next repotting time this is the composition.

Now, you may have recognized that this tree does not exhibit the ideal design. There’s a slight curve to the trunk, taking it from left to right. If we’re following the standard design principles, the first branch should appear on the left side of the tree. Then second branch right, third branch in back, and so on. However … there’s also nothing saying you can’t break rules. I think this is most true when you’re maintaining a venerable old bonsai. This tree has been in training for about 30 years now. Should I remove that lowest branch because it’s on the wrong side of the tree? Not on your life! It can take a very long time to get your branches to the right thickness, and that right-hand branch is right at half the thickness of the trunk where it emerges. The relative proportions make it look very natural. Also notice that as you move up the tree, the branches get progressively less thick but remain proportionate with the trunk thickness. From this standpoint, the tree certainly complies with the rules. So to me, this is a very pleasing bonsai and looks its age.

Let me know your thoughts on this one.

Spring Work – Potting And Repotting

by Zach Smith | Mar 4, 2018 | Bald Cypress, Care, Chinese Elm, Elms, Potting, Pruning, Soil

The beat goes on. As I mentioned yesterday, spring is the time when you need to do all sorts of things all at once. One of those things is potting. Another, related, is repotting. Here are today’s subjects.

Here’s my Chinese elm, Ulmus parvifolia, that you can learn more about on its Progression page. Last fall, I decided that this view of the tree didn’t really show it off to best advantage. I liked the one below better.

Better trunk movement, better tapering transition, all in all just better. Today it was time to turn it in the pot.

I took off only enough root to fit the tree in the pot, including a small amount at the bottom of the root mass to allow for a little drainage layer (till the roots grow down into that area, of course). The tree won’t mind this at all.

Tied down and filled in with fresh soil. As you may be able to see, the tree is leafing out. I prefer to do my work on Chinese elms when the buds are swelling, not in the dead of winter. I also lift them from the growing beds at this time.

Here’s a two-tree Bald cypress planting I got from a fellow grower last fall. I figured it would make a nice composition more or less as-is. Today it was time to make this happen.

I happened to have this antique Tokoname tray on the shelf, and I thought it would complement these two trees very well.

A good bit of root had to go, in order to fit these two trees into the tray properly. I also took off a lot of the upper parts of the trees. That should help balance things.

Here they are, placed in the tray.

And the tray filled in with soil. These trees are already budding, and I don’t anticipate potting them will delay their growth too much. In a couple of weeks, they should be filled out pretty well.

Note:

Comments are closed. Remember to use the new Insider’s Club Form to post your questions and comments. This helps everybody learn and help and this is where I am now posting responses to your inquires and comments. (You’ll find the forum by scrolling up; it’s on your right.)

Ground Growing For Size – How To Make Them Fatter Faster

by Zach Smith | May 10, 2017 | Collecting, Potting, Pruning, Soil, Sweetgum

I posted this photo last December of a Sweetgum (Liquidambar styraciflua) I had been growing in the ground for a few years. The tree started out as something just beyond a seedling, in a nursery pot. I was developing it in the pot, using directional pruning techniques to create taper and movement. But the tree just wasn’t fattening up as I wanted it to. So I put it in the ground, knowing that the fastest way to make a smaller tree into a bigger tree was to give it room to grow.

This photo shows one classic way to get thickening in the base of your tree: letting a low shoot run. And boy, did this one run! In the process, I now have a 3″ trunk base whereas I started with a 1″ base just a few years ago.

So I chopped off the low leader in December and sealed the chop, with the idea of lifting the specimen in May (the best time to collect Sweetgums).

And so, on May 1st I sawed this tree out of the ground. Here it is with its root mass and soil ball (I shook off what I could). It’s grown like a weed, as you can see.

First I gave the root mass a good washing off. I don’t want any native soil, as it’s not needed.

Referring to the above picture to your right, the tree will go into a fast-draining coarse bonsai soil, which will promote regrowth.

I also cut back the long leaders; they aren’t necessary at this point.

Take special note of the branch growing from beneath the large cut. This is important to ensure I don’t get any dieback into the root from this area. I was careful to leave the branch collar when I chopped the big leader, also for this purpose. But this branch is my insurance policy. I’ll leave it for a year or so (though I will keep it cut back while developing the structure of this tree).

The next step. All of the foliage is gone now. This is absolutely vital when collecting deciduous trees that are in leaf. If you fail to do this, the tree continues transpiring moisture through the leaves and will literally dry out.

I’ve also cut back the roots in the first stage. You can see one of the coiling roots that will need to go.

You can also see the trunk line of this specimen and the massive taper from the base. The trunk measures 3″ across above the root zone – so I’d say my ground-growing effort succeeded.

Now I’ve got the root zone cut down to size. Notice how much smaller it is in this photo than in the previous one.

It’s a common mistake to leave too many and too long roots on a collected tree.

Remember two principles when working on the root zone of a newly collected tree:

the roots need to be cut back enough so that they will fit in a bonsai pot in the future, including cutting them shallow enough for that same purpose; and
they need to be 2-3 diameters long so you can build taper in them when smaller roots sprout from the cut ends.

What’s the best front for this tree? I have at least a couple of options, and I don’t have to choose now.

Should the trunk be chopped back farther? I can see a likely spot for a chop. But again, I have options and don’t have to choose now.

After a good dusting with rooting powder, here’s the tree all potted up. All cuts 1/4″ and over were sealed with cut seal. This has to be done every time you collect a tree.

And a third possible front. I’m thinking this is my favorite.

Sweetgums are great to work with. They grow fast and will regrow from chops very well. It does take some time to build ramification and get some leaf size reduction. But all in all, they are one of my very favorites.

Today this tree is showing signs of pushing new buds, so it looks like the harvest was successful.

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