Process bark chunks into smaller bonsai substrate

[Cruiser]

27 gallons of small nugget df bark. $10.00 from a local landscape supply.

The chunks are mostly too big to use for bonsai. Sifting nets some useable particles, but not many; and definitely not worth the time and labor involved.


Bark chunks need to be broken up. What is an efficient way to do this?

An electric chipper. (My wife bought this one used for $30.00.) Most are too weak to handle serious tree work, but they can gobble up small branches nicely.



I decided to chip and process 10 gallons of bark.
Chipping took 13 minutes. Here is what the bark looked like after. Most pieces were reduced to 1/2” or under.



Chipped bark was then sifted through a 1/2” screen.

It took 10 minutes. Sifted particles are 1/2”+. Most wood shards were removed at this step.

Remaining…



Remaining bark sifted through a 1/4” screen.

This step took 12 minutes. Sifted bark ranges from 1/4”- 1/2”.

Remaining…



Remaining bark sifted through 1/8” screen.

This time it only took 8 minutes. Sifted bark is 1/8”-1/4”. It looks just like fine-grade orchid bark.

Remaining fines…


Particle size comparison.


RESULTS:

Particle size distribution of chipped small nugget df bark:

<1/8”- 9%

1/8”-1/4”- 26%

1/4”-1/2”- 37%

>1/2”- 28%



Time involved to process 10 gallons

43 minutes total

Chipping- 13 min

1/2” sift- 10 min

1/4” sift- 12 min

1/8” sift- 8 min



Was it worth the effort?

For me, yes. I utilize 1/8” up to 1/2” particle sizes. For 6.3 gallons of sifted product it cost 30-40 minutes of time and about $3.00.

For comparison, 2 gallons of 1/4” df bark ordered from online costs $34.00 plus shipping.

Also, from a non-monetary standpoint I prefer to use df bark as a bonsai substrate. It’s a by-product of the timber industry, is locally sourced, and roots appear to love it.

 

[nuttiest]

Sometimes depot has that pine mulch, it is super-shred and great potting soil. I use the mini nuggets now and with a little peat, perlite and lime it is fine for 3 gallon or larger pots.
I like your screens. Ever think about building a giant upright column of successively smaller screens and dumping in the top? It would need wheels so it could be shaken back and forth

 

[Cruiser]

I tried the column approach using 3 nested 5 gallon buckets. No wheels below.

Bucket bottoms were removed then screen was attached. 1/2”, 1/4”, and window screen.

It didn’t work as well as hoped. It was annoying to shake and pry apart the buckets to remove substrate.
Perhaps if there was more surface area to process more material at once and if there were wheels it might work better.

 

[nuttiest]

Old filing cabinet or dresser, but then you would have to cut through.

 

[Cruiser]

I should add…
My biggest takeaway from this is that a shitty electric chipper works great for breaking down large bark chunks into ideal sizes for bonsai.

In addition to the small nuggets, it also chips pieces up to 4”.
Larger chunks may even be preferable to the small stuff since there seems to be less wood mixed in.

 

[nuttiest]

That is the perfect size ... I like to put large grain pool filter sand with that size because because the pieces still touch but are always separated.

 

[Cruiser]

That is the perfect size ... I like to put large grain pool filter sand with that size because because the pieces still touch but are always separated.

Is the sand equal in size to your bark? Do you notice much difference between using it vs not?

I mix bark with equal-sized pumice. It drains better and appears to prevent mycelium from becoming too dense.

 

[nuttiest]

Is the sand equal in size to your bark? Do you notice much difference between using it vs not?

I mix bark with equal-sized pumice. It drains better and appears to prevent mycelium from becoming too dense.

No, filter sand is much smaller than perlite, but much larger than play sand. I only use it for nursery containers, because every time I get something nice from the nursery, there are fat white roots and in that bark-sand soil + green time release fertilizer. Is it fat new roots you want to avoid? Use 100% pumice

 

[Cruiser]

No, filter sand is much smaller than perlite, but much larger than play sand. I only use it for nursery containers, because every time I get something nice from the nursery, there are fat white roots and in that bark-sand soil + green time release fertilizer. Is it fat new roots you want to avoid? Use 100% pumice

Nope, fat new roots are welcome.

It's overly dense fungal patches I want to avoid. The bark and fertilizer I use develops rich colonies of it, but if there’s too much, it slows drainage.

 

[Cruiser]

Another 5 gallons of bark was processed in the electric chipper. This time it was chipped twice.

Resulting particle size distribution:
<1/8” (fine)- 8%
1/8-1/4”- 37%
1/4-1/2”- 37%
>1/2”- 18%

-Chipping the bark for a second time goes a little quicker than the first feed.
-Net amount of fine and 1/4-1/2” size particles is the same as when chipping once.
-More 1/8”-1/4” particles were created at the expense of >1/2” particles. This is a good result. Useable bark increased to 74% from 63%.