Is it bad if soil particles have very different sizes?

[Bon Sai]

Hello,

I mixed different kinds of soils which I intuitively thought had to be good, and they had different particle sizes, which again I intuitively thought wasn't a bad thing.

But I've been reading about soils on the Internet and now I'm not sure about this.

So now I'm worried

My soil composition (more or less):

- 40% fired DE (red): 4-9mm
- 40% zeolite (white): 4-5 mm
- 20% mix of pumice and similar things: 2-10mm

The coin is 5/8" (16mm) wide.

 

[Adair M]

Yes, mixed sized particles will pack and then hold too much water. For best drainage, seive them. The larger particles for larger trees and conifers. The smaller particles for small trees and deciduous.

The smaller particles will tend to hold more water than a mix made from larger particles.

 

[Anthony]

Think of how concrete works.
Good Day
Anthony

 

[WNC Bonsai]

With most bonsai try to stay in a 2-6mm range to avoid drainage issues.

 

[Anthony]

@Cofga ,

Is that 6 mm 100% of the soil?

Is that a mix of 2 to 6 mm ?
Good Day
Anthony

 

[WNC Bonsai]

I use a sieve that is 6mm and another that is 2mm. I sice the materials through the 6mm sieve first and separate the <6 from the >6 mm size fraction. Then I sieve the <6mm stuff through a 2mm sieve. That way I end up with a mix that is 2-6mm. You can use the >6mm stuff on the ground under your plants and the <2mm stuff from very small bonsai.

 

[0soyoung]

You can use the >6mm stuff on the ground under your plants and the <2mm stuff from very small bonsai.

Small plants have the same kind of roots as do larger ones.

The smaller the particle size the higher the saturation zone --> deeper pots for using smaller stuff

 

[amatbrewer]

There is a great article "Introductory Soil Physics 1.2" in the resources section, and there is (was?) a rather long but very informative thread (that I can't seem to find now) explaining the whys behind particle size as well as many other soil related topics that I found really educational. I personally prefer to learn the "why" rather than just the "what". The why helps me know how/when to apply (or not) the what.
Hope this helps.

 

[Velodog2]

Anyone want to discuss “perching”?

 

[Solaris]

Anyone want to discuss “perching”?

The internet is a bountiful source of wisdom on the subject.

 

[amatbrewer]

I would actually love to discuss, or be directed to a discussion on, wicking, in regards to bonsai.

 

[Velodog2]

My understanding, relevant to particle size discussions, is that perching relates to how far water will drain from a substrate composed of particles of a given size. The perch height is how high water will be retained as a result of surface tension. Retained as in the particles are saturated with no air between them. The water will not drain further as a result of gravity. The smaller the particles, or more accurately the smaller the pore sizes between particles, the higher the water will sit. This height is independent of container diameter or depth.

This is relevant because saturated soil is bad for roots that require air. I’ve always figured that this is therefore a more Important principle tor shallow containers because for a given particle size and perch height a greater proportion of the container volume will be saturated than for a deeper container. And therefore it becomes more important to have a larger particle size in a shallow container. It may also be relevant to the practice of using larger particles at the bottom of a pot to reduce or eliminate the saturated area.

How’d I do? Not the most succinct explanation I’m guessing. Perching is real but my application of it to bonsai pots is speculation. I also honestly can’t remember where I read such things.

 

[markyscott]

there is (was?) a rather long but very informative thread (that I can't seem to find now) explaining the whys behind particle size as well as many other soil related topics

Here’s the thread
https://www.bonsainut.com/threads/introductory-soil-physics.24970/

Here’s the resource
https://www.bonsainut.com/resources/introductory-soil-physics.29/

And I wrote a series of articles for the ABS Journal
ABS Journal 2017 Vol.51/2; 2017 Vol.51/3; 2017 Vol.51/4; 2018 Vol.52/

 

[sorce]

The red might not be DE.

Either way I have things in similair sized, AND MORE retentive soil.

No worries.

Sorce

 

[Anthony]

Here is the application of Scott's [ @markyscott ] technology.
Thanks Scott.
Shallow pot retains more water and soil is around 3 mm plus compost.
Good Day
Anthony

Was Nicodemia d. Now Buddleia i.
http://www.plantoftheweek.org/week335.shtml
Handles cold - 48 deg.F [ 9 deg.C ]

A very thirsty shrub, from Madagascar, flowers are heavily scented.
Pot is one inch deep, soil is 3 mm silica based gravel 50 %, 3 mm
crushed porous red brick 50 %, and aged compost at 3 parts.

Placement full sun. Around 15 years+ and loves moss.

 

[Cosmos]

I wouldn't say that the particles in that picture are of "very different sizes" at all... You may be overthinking this.

 

[Bon Sai]

Small plants have the same kind of roots as do larger ones.

The smaller the particle size the higher the saturation zone --> deeper pots for using smaller stuff

But still many say the bigger the bonsai the coarser the soil. I was planning to have 2 kinds of soil: one for big trees and another for small ones, but now I'm thinking that maybe I should use the same soil for all.

There is one thing I see here: with small pots, or with roots that fill almost all of the pot, coarse soil is difficult to "fit" in the pot and among the roots. Maybe this is the reason they recommend finer soil for small trees.

I think the next soil I prepare will be something with uniform medium sized particles, and use it for all tree sizes.

 

[Bon Sai]

The red might not be DE.

Look up Terramol images.

 

[Bon Sai]

I wouldn't say that the particles in that picture are of "very different sizes" at all... You may be overthinking this.

I probably overthink in general

 

[Tieball]

I probably overthink in general

Is the tree in the mixture growing well and draining well? .....That’s the primary objective I come back to when I start to overthink details.