Top soil roots

[Mickeyjaytee]

Hi guys,

So I’ve been watching a few of bonsai-ens videos and they discuss how the roots. specifically in the top layer of soil, don’t really start to develop until they are a bit deeper into the soil due to light.

I was thinking would a thick layer of mulch help with this? For pre-bonsai only of course.

Or do we want that “root” taper once placed in the bonsai pot? Not that you couldn’t train them downwards once repotting though

Sorry if the question seems silly. I’m a complete beginner and good rain water is hard to come by in Perth summers and only the best for my trees!

Thank you for any advice!

EDIT: Spelling

[shibui]

In my experience roots do not have any problem with light. It seems to be a common misconception because roots above ground do die but that seems to be due to the roots drying out rather than light as such. Roots with their tips under the soil will still grow and do everything they are supposed to.
There was also a widespread theory that roots well buried thicken faster than those exposed on the surface. From a plant growth perspective I can't see why that would be so. Thickening is related to how much sap passes through whether that is trunk and branches above ground or roots below so roots should thicken whether they are exposed to light or not.
Surface roots definitely thicken if they are the main roots supporting the tree - ie most down growing roots below have been removed.

good root pruning so that the lateral roots are doing most of the work will give you much better thickening than covering them with mulch.

[Stevie_B]

I always thought it was due to the nutrients 'leaching' towards the ground as it is watered, and also that the tree is naturally trying to grow deeper for stability.

[treeman]

Hi guys,

So I’ve been watching a few of bonsai-ens videos and they discuss how the roots. specifically in the top layer of soil, don’t really start to develop until they are a bit deeper into the soil due to light.

I was thinking would a thick layer of mulch help with this? For pre-bonsai only of course.

Or do we want that “root” taper once placed in the bonsai pot? Not that you couldn’t train them downwards once repotting though

Sorry if the question seems silly. I’m a complete beginner and good rain water is hard to come by in Perth summers and only the best for my trees!

Thank you for any advice!

EDIT: Spelling

I believe you are talking about the development of the nebari?
There is little doubt that covered roots develop faster than exposed roots. (Everything else being equal) It is standard practice in Japan to cover the nebari with soil on trees in training and even some finished trees like satsuki when they are not being exhibited. This does 2 things. It keeps the bark of the nebrai from drying out from sun and air, becoming hardened and slowing the expansion and cell division and, by keeping the secondary roots - those that spring from the nebari - slightly deeper there is less fluctuation in temperature and moisture and they are more likely to develop and ramify than if the are immediately under the top layer.
This is one reason that moss if preferable to stones for the top layer.
So, if you are developing a tree, keep all the roots and most of the nebari covered. The correct depth is when you are just able to detect a flaring at the bottom of the trunk. Of course there are always exceptions but this is best practice, especially for deciduous trees. You can begin to expose the nebari on older trees or those you wish to exhibit.
I probably should add that covering an old hardened nebari could lead to trouble!

[Mickeyjaytee]

Thanks for the replies guys, I highly appreciate it!

Yes developing Nebari is what I mean but, I should be more specific. I have quite a few saplings and seedlings and thought on their journey over the years growing size and going from bigger pot to bigger pot if mulching the top layer would help the surface roots develop more and thicken up as opposed to digging down a fair way to get to the thicker roots to develop nebari? (If that’s what people do, I’m unsure).

I will say I do live in Perth and summer is really hot and dry and keeping on top of watering is going to be hard so mulching would benefit me anyway.

Complete beginner as I said! Curious if anyone has tried this and what results there are or if it’s just a waste of time.

This is for pre-bonsai and tree growth only not bonsai in a bonsai pot.

Thank you!

EDIT: Sorry, treeman I do believe you answered the question. Thank you!

[thoglette]

Yes developing Nebari is what I mean but, I should be more specific. I have quite a few saplings and seedlings and thought on their journey over the years growing size and going from bigger pot to bigger pot if mulching the top layer would help the surface roots develop more and thicken up as opposed to digging down a fair way to get to the thicker roots to develop nebari? (If that’s what people do, I’m unsure).

Roots grow underground. So keep your soil mix over the roots.

Evan also recently reminded those of us west-of-the-rabbit-proof-fence that soft soil will result in roots that run straight to the side of the pot: a mix with coarse, hard stuff is needed to force the roots to work (and divide).

Also at the sapling stage roots need to be sorted, straightened and trimmed every year (depending on species). It's hard and rather risky doing this once the tree has made it to "trunk ready" size.

On mulch: in Perth mulch (whether organic or an old piece of denim), along with sitting your trees on a tray full of gravel and water, makes sense in hot weeks in the height of summer (like last summer). But it creates risks at other times. Unfortunately, when it comes to the top centimeter of soil, there's no substitute for daily (or twice daily) watering in summer. For saplings, just use a deeper pot and add another 1/2 inch of your standard mix between Xmas and Easter.

P.s. there's a number of clubs here in Perth (and Mandurah & Bunbury) and I can recommend joining (or just visiting) any of them.

[Mickeyjaytee]

Yes developing Nebari is what I mean but, I should be more specific. I have quite a few saplings and seedlings and thought on their journey over the years growing size and going from bigger pot to bigger pot if mulching the top layer would help the surface roots develop more and thicken up as opposed to digging down a fair way to get to the thicker roots to develop nebari? (If that’s what people do, I’m unsure).

Roots grow underground. So keep your soil mix over the roots.

Evan also recently reminded those of us west-of-the-rabbit-proof-fence that soft soil will result in roots that run straight to the side of the pot: a mix with coarse, hard stuff is needed to force the roots to work (and divide).

Also at the sapling stage roots need to be sorted, straightened and trimmed every year (depending on species). It's hard and rather risky doing this once the tree has made it to "trunk ready" size.

On mulch: in Perth mulch (whether organic or an old piece of denim), along with sitting your trees on a tray full of gravel and water, makes sense in hot weeks in the height of summer (like last summer). But it creates risks at other times. Unfortunately, when it comes to the top centimeter of soil, there's no substitute for daily (or twice daily) watering in summer. For saplings, just use a deeper pot and add another 1/2 inch of your standard mix between Xmas and Easter.

P.s. there's a number of clubs here in Perth (and Mandurah & Bunbury) and I can recommend joining (or just visiting) any of them.

Thank you for the reply! Geez, I have so much to learn! Could you suggest a few clubs around Perth I could join? Very eager!

Thanks a tonne!

[SuperBonSaiyan]

Along this topic, how do you expose the additional girth from root flare beneath the trunk of the tree?

I have recently been lucky enough to acquire a Hinoki which was around 2cm at the base (where the soil was), but during re-potting I discovered that the roots flared out quite a bit - around 5-6cm below the original surface soil.

I've drawn a picture to try and make it more clear.



How do I plant the tree now to expose the flared portion below the black line?

The roots flare out in "most" directions (one side has less flare than the other 3. Think North, East, South, West - Only one direction doesn't have as much roots flaring).

The area underneath the root flare is mostly hollow (no tap-root).

So, do I plant it on a mound?... Plant it on an angle?

Also, how do I encourage roots to grow from the one side that doesn't have as much at the moment? Have that side face the sun or away from the sun?

[KIRKY]

SBS a photo showing 360 deg would help us see exactly what your problem is. Otherwise we could lead you astray.
Suggest you start a new post.
Cheers
Kirky

[treeman]

Along this topic, how do you expose the additional girth from root flare beneath the trunk of the tree?

I have recently been lucky enough to acquire a Hinoki which was around 2cm at the base (where the soil was), but during re-potting I discovered that the roots flared out quite a bit - around 5-6cm below the original surface soil.





How do I plant the tree now to expose the flared portion below the black line?

The roots flare out in "most" directions (one side has less flare than the other 3. Think North, East, South, West - Only one direction doesn't have as much roots flaring).

The area underneath the root flare is mostly hollow (no tap-root).

So, do I plant it on a mound?... Plant it on an angle?

Also, how do I encourage roots to grow from the one side that doesn't have as much at the moment? Have that side face the sun or away from the sun?

Firstly, lucky you on finding a good hinoki. Secondly, when you repot (at the correct time), you can carefully scrape soil from between the main roots with a fine hook or sharp chopstick trimming those fine roots that you don't need as you go and leaving the heavier ones that you think are in a good position. (more or less the same level) Expose the nebari gradually over 3 or 4 repotting sessions.
Also, to encourage an even and balanced nebari, trim the heavier ones more than than the weaker ones - if you touch them at all - every time you repot. But never cut heavy roots unless there are finer roots behind the cut! be extremely careful with Hinoki. They do not like masses of root removed at one time. 50% would be about the limit.

[thoglette]

Could you suggest a few clubs around Perth I could join? Very eager!

The two major clubs in Perth are
The Bonsai Society - meets on a Monday night in South Perth
The Bonsai Workshop - meets on a Saturday afternoon in Doubleview.

Many people are members of both as each has a slightly different focus.

If you're closer to Bunbury or Mandurah, a club has recently formed in each of these locations. But I don't know their URLs (maybe someone else does)