Which soil is best for thickening trunk of a juniper in a pot?

[Ozz80]

Hi all. Although I've been interested in bonsai making for a long time, I have recently got more serious into the hobby. I read a lot of documents, watched several videos and got a bit confused about best soil mix for trunk development in a pot, specifically for junipers. Is it wise to leave them on the nursery pots with organic soil, or put them to slightly wider and shallower training pots with a permeable bonsai soil? (Materials I am considering to develop has .5-1 inch trunk thickness at the moment and I plan to develop them about 10 - 15 years, hoping that I'll get a final thickness of 2 inches at the end)

 

[Shibui]

IMHO, soil mix does not dictate trunk thickening. Not does container shape. Trunk thickening is directly tied to the amount of growth. To get good growth, use a container and soil mix that allows you to get best growth.
If a deeper pot allows better growth then use them. Roots can be pruned to fit a bonsai pot when the tree is ready for that.
If organic soil gives better growth then use it. Organic soil can be replaced with soil mix suited to a bonsai pot when required.

The reason for so much different opinion is that different things will work better for different people in different places.
I get best trunk growth in pots using nursery pots with organic soil mix. Others may do better with a different approach.
I also get much better trunk thickening combined with good trunk taper by allowing sacrifice branches.
I have also trialled smaller pots inside larger pots to allow escape roots for increased trunk thickening. Jury is still out as to whether that's a useful technique.

 

[ponderingsage]

Great answer given above.
The condensed version would be if you wanted to grow bigger don’t put it in a small pot. The ground or something like an Anderson flat or homemade wooden boxwould be a good option for a thickening.

 

[Ozz80]

I respect that you guys are gracious to give an answer and I don't want to be rude in my very first post, but frankly speaking, the knowledge that development of the trunk is dependent on the growth of the foliage, or using a big pot or that directly planting on the ground helps the growth is trivial, even for a newbie. My question was whether organic soil or bonsai soil is better in the development phase. If you are saying that it does not matter, I'll take that. But if you are saying " it depends on the situation" then it is not an answer I am afraid. I have to ask, It depends on what situation?

As Wittgenstein said, "Whereof one cannot speak, thereof one must be silent"

 

[BartelBe]

That which has been said many times by those experienced enough to know should be referenced for all to learn. Try our own @leatherback's "

Thicken trunks for bonsai. 3 Ways to grown trunks out."​

The composition of the soil is the least relevant, for that matter.

 

[roberthu]

Use a big pot with top soil or potting soil, apply heavy fertilizer once the roots are established. I am growing some materials that way myself and the results are fairly good.
The challenge is knowing when the roots are established enough to use large amount of water and fertilizer.

 

[Ozz80]

That which has been said many times by those experienced enough to know should be referenced for all to learn. Try our own @leatherback's "

Thicken trunks for bonsai. 3 Ways to grown trunks out."​

The composition of the soil is the least relevant, for that matter.

Though this video is irrevelant to my question, I had already watched this and more from this channel, eventually which I found to be one of the most logical and beneficiary free material on the internet. Thank you very much for veryfying this channel's competence and expertise. This channel suggests getting to the bonsai soil as soon as possible, which I'll follow. Kudos to @leatherback doing this for free.

 

[nuttiest]

It depends on what situation?

It depends on what you mean by better.

 

[Shibui]

My question was whether organic soil or bonsai soil is better in the development phase. If you are saying that it does not matter, I'll take that.

I'm definitely saying it does not matter what soil you use in the development phase.
What does matter is how you can care for the trees growing in the soil mix. In my situation, an organic mix and deeper pots gives better results, probably because of the hot, dry summers here. Other people will have different climate or different care and are likely to find something different works better for them.

 

[Wires_Guy_wires]

Organic beats inorganic in my book.
But the watering has to be adjusted since organic can hold water for a long time.

50/50 organic/perlite seems to be universally good.

 

[Desert O'Piñon]

Situationally speaking, @Shibui and I have similar hot and dry climates in opposite hemispheres, but likely similar substrates may work for us. But those who live in a cooler, or wetter, or more humid, etc climates will have entirely different needs for the roots of our trees. There is a certain amount of trial and error required, but the more bonsai folks you can have discussions with in your own area, the less you will need to experiment. I'm extremely remote; the nearest bonsai club or nursery is at least a four-hour drive, so it's going to take me a few years to develop an "ideal" mix for seedlings, for trunk development, for ramification, and for refinement. That's why this forum holds so much value for me.

 

[SeanS]

If you can carefully monitor water/fertilizer needs of the plant and then keep up with the those needs, a free draining aggregate soil may be best. If you can’t due to lack of time or not being fully invested just yet then maybe a more water and fertilizer retentive organic soil in a deep pot would be best.
Both options would still produce growth which would then produce thickening.
That is why we say it depends on the person and the conditions your plants will be exposed to.

 

[Gonzoe]

Though this video is irrevelant to my question, I had already watched this and more from this channel, eventually which I found to be one of the most logical and beneficiary free material on the internet. Thank you very much for veryfying this channel's competence and expertise. This channel suggests getting to the bonsai soil as soon as possible, which I'll follow. Kudos to @leatherback doing this for free.

Idk why everyone is so hard pressed on giving an answer… Imo if not sticking it in the ground, which I don’t do because I don’t have the space, is potting is into a fairly large pot but leaving space for the tree to grow as well as being able to still upsize the pot. All trees do better in a proper bonsai mix basically, not organic soil mixtures. So something like half and half lava rock and akadama, pricey but worth it and use good fertilizer like biogold. Some pruning/pinching to move energy to the trunk as well as roots to promote good growth. Then just upsize as needed which is kinda hard to tell but basically just don’t let the roots get messed and and logged up.

 

[Ozz80]

Situationally speaking, @Shibui and I have similar hot and dry climates in opposite hemispheres, but likely similar substrates may work for us. But those who live in a cooler, or wetter, or more humid, etc climates will have entirely different needs for the roots of our trees. There is a certain amount of trial and error required, but the more bonsai folks you can have discussions with in your own area, the less you will need to experiment. I'm extremely remote; the nearest bonsai club or nursery is at least a four-hour drive, so it's going to take me a few years to develop an "ideal" mix for seedlings, for trunk development, for ramification, and for refinement. That's why this forum holds so much value for me.

Thank you very much, it is a good advice to look what nearby bonsai guys are doing. Actually there's one professional bonsai nursery near me and the owner uses bonsai soil for nearly everything, including baby saplings. I live in Istanbul with a yearly total precipation of 865 mm's (34 inches), which is higher than most cities in the Medittarenean area and even northern Europe, while rains are mostly concentrated on winter. I can handle dry hot summers by constant monitoring and daily watering, but I have nothing to do for heavy winter rains.

Eventually, everything in a pot under direct sunlight has to be watered daily here. Meanwhile, my garden with poor drainage becomes a swamp during winter rains.

Maybe, using zeolite and / or a small amount of spagnum moss in the soil mix could be considered for water retention during hot summers, without losing the permeability concerning rainy winters.

BTW, I am not sure you and @Shibui have similiar climates.

 

[Ozz80]

Eventually, everything in a pot under direct sunlight has to be watered daily here.

In summer of course.

 

[Desert O'Piñon]

BTW, I am not sure you and @Shibui have similiar climates.

You are correct, my error. Rainfall there is about double here annually, but still significantly low. His temperatures are also lower than I thought.