Growing Out: Potting Soil vs. Bonsai Soil

[Redwood Ryan]

Hi everyone,


While I was up at Meehan's Miniatures on Wednesday, I was talking to Martha Meehan about growing trees out in preps for bonsai. I asked what would result in the best growth, in terms of soil. She told me that, without a doubt, I would get the best growth in a regular potting soil. I'm considering doing this for my pre-bonsai to get them healthy and growing actively again. What is your all's opinion on this concept? Is it just that bonsai soil is meant to slow growth, due to less organics?

 

[Vance Wood]

Hi everyone,


While I was up at Meehan's Miniatures on Wednesday, I was talking to Martha Meehan about growing trees out in preps for bonsai. I asked what would result in the best growth, in terms of soil. She told me that, without a doubt, I would get the best growth in a regular potting soil. I'm considering doing this for my pre-bonsai to get them healthy and growing actively again. What is your all's opinion on this concept? Is it just that bonsai soil is meant to slow growth, due to less organics?

I would say this might be a possibility with certain species of trees. With conifers maybe not so much. Remember that bonsai soil is the way it is for a purpose, it is not arbitrary.

 

[thams]

I've had the same conversation with her a few times as well. She recommends potting soil when trying to trunk up and get an overall larger tree. Once the tree is the size/thickness you want then you should transfer to bonsai soil to work on roots and branch development. She recommended potting soil for an olive that I'm looking to grow much much larger. But bonsai soil should be used for trees that I'm looking to refine.

 

[Dav4]

I've got shimpaku junipers growing out in pond baskets and nursery cans full of soil conditioner- basically composted pine bark- and they grow like gangbusters.

 

[cmeg1]

Yea,I would agree with Vance.I use potting soil because it is moist enough for me while I am working and it has me used to only having to water a few times all winter while in the deep cold frames.
I am hoping my pines I purchased from Meehans do good for me in potting soil.They were in potting soil when purchase last week.When I put them in the colanders I noticed quite a bit of myco growing in the small pots.
By the way,I would highly recommend plastic colanders for growing trees in potting soil.It works fantastic.If you like you can fasten upside-down clay saucers in the bottom of them.
Here are pictures of potting soil and colanders and such.

 

[cmeg1]

Now,someday when I have more free time I am going to work on the soil.For now with growing everything out,it is colanders and potting soil.
Here is the rampant growth on some Coreana Hornbeams last season from Meehans.I could not even handle it.They had to go in the ground by late summer.They were growing in 13" colanders.

 

[esons]

I wish I read this thread before all the other crazy soil debate threads. I figured I needed to plant everything into a perfect particle sized inorganic mix, and now I need to water my seedlings twelve times a day.

 

[Cadillactaste]

Explains a lot...my rosemary seems to have potting soil around its roots...with then bonsai soil making up the rest of the pot. Like it's in a second stage of some sort in potting.

 

[Vance Wood]

You have to remember that not all potting soils are the same and that most potting soils will break down and become compacted rather quickly depending on the content. My fear is that many reading this thread will think that the soilless mixes we adhere to around the bonsai community seem to be only marginally necessary, and that there will be a wholesale migration to potting mixes for bonsai which I believe is a mistake.

 

[GrimLore]

Explains a lot...my rosemary seems to have potting soil around its roots...with then bonsai soil making up the rest of the pot. Like it's in a second stage of some sort in potting.

Your plant was more then likely slip potted if I remember correctly prior to shipment. By them leaving the growing medium on the roots it prevented the coarse Bonsai medium from destroying the roots during transportation. No harm in that for certain.

Grimmy

 

[coh]

We've been over this time and time again - the thread title is "Growing Out: Potting Soil vs Bonsai Soil". So the subject is not finished or near finished bonsai, it's trees that are still in the early development stage (which often means trunk development). Many people use mixtures that are very much unlike bonsai soil for this stage. Or, they plant in the ground which is definitely unlike bonsai mix.

If anyone reads this thread and comes away with the belief that they should plant their prized, show ready bonsai in potting soil, they need to work on their reading comprehension. That said...I'm sure one could grow a finished bonsai in potting soil, provided they adjusted their watering and fertilizing.

 

[KennedyMarx]

I have my doubts as to wether or not she's correct, but of course I don't have anything to disprove her claim. Logically, I would imagine that the coarser soil would lead to more feeder root growth which in turn would lead to faster growth up top. You have to fertilize more with bonsai soil, but I don't see that as a problem. From what I have seen in pictures, in Japan they grow out material in pots and colanders all in bonsai soil. Not just pines and junipers, but maples, chojubai, etc.

 

[drew33998]

It would seem to me that if one is trying to grow out the nebari, thicker roots at the base, then potting soil would be the best as the roots can "run" a lot easier. That said you wont get the fine ramification of feeder roots that bonsai soil offers. It depends on the specific tree I think. Obviously you are going to need to get the fine ramification of feeder roots closer the base of the trunk when trying to put the tree in a smaller pot. This is all hypothesis on my part though.

 

[Umeboshi]

I have noticed that many bonsai nurseries have their prebonsai in potting soil. I figured the reason was cost and ease (no sifting, less watering). I wouldn't put my developing trees in potting soil, I want coarse particles and heavy fertilization to bulk up trees.

Isn't it common to reduce the particle size of your soilless mix somewhat when your tree goes from development to refined to slow down growth? Wouldn't this be contrary to the idea of potting soil to speed development?

 

[Dav4]

Four year old shimpaku cuttings from the same parent, struck in a peat/bark nursery soil. The two on the right were placed in a granular, inorganic soil 3 years ago while the two on the left have been grown on in bark soil conditioner...same sun exposure, same water and fert schedule- watered daily and fertilized weekly during the growing season. This is far from statistically significant, but in my relatively limited experience growing out shimpaku from cuttings, they do much better in a 100% organic soil, both in nursery pots and in pond baskets. I know I'll have to deal with the roots eventually, but I've never had a problem aggressively root working them when done correctly. Mind you, the trees pictured in the pond baskets were twisted up with wire and repotted this past February...they're growing like weeds.

 

[coh]

Bark soil conditioner is somewhat more coarse than standard potting soil, right? I haven't been able to find the stuff locally but it sounds like it's just somewhat composted fine bark...so it must start out at least a little more coarse than potting soil. However...a mix of potting soil and perlite might give approximately the same porosity?

I've stated in other threads that I've had good results using a mix based on a standard bagged nursery container "mix", which isn't really soil but a combination of peat, bark and perlite. I amend this as needed with standard potting soil for some plants, or more perlite for others. Does it give me more growth than using a bonsai soil and heavy fertilizer? I have no idea, I do it mainly because it's cheaper. I haven't seen any significant problems with the root systems after doing this for several years.

I am doing a comparison with trident maple seedlings, planted in a variety of "soils" (ranging from potting soil/perlite to turface/grit/bark and pumice/lava/akadama) but as Dave noted, the sample size is pretty small. I will eventually post results. I will note that only one of them has died, and it was one of the ones planted in a coarser pumice/lava/akadama mix. Make of that what you will

Chris

 

[Eric Group]

The size of the pot you plant them in will a fret the rate that they grow as well...

Overall, I think it is pretty clear that while they are planted in a nursery can of a decent size or in the ground- an organic, rich potting medium like nursery potting soil (Miracle Grow, Pro Mix, or whatever you prefer) is fine and probably going to produce the most rapid growth and development.

Once you begin to reduce the size of the container, that is when you need to reduce the size of the root ball and this need the fine root ramification you get from a coarse inorganic mix like modern Bonsai soils are normally comprised of. This will eventually lead to slower growth and development/ trunk thickening... As you are most likely pruning to increase ramification, not letting sacrifice branches run, and your roots are confined to a smaller space limiting the size of the root ball and eventually limiting the length of new runners/ growth overall.

In short... For ease, affordability and expedience- you are just fine using potting soil for young trees.

 

[Vance Wood]

The size of the pot you plant them in will a fret the rate that they grow as well...

Overall, I think it is pretty clear that while they are planted in a nursery can of a decent size or in the ground- an organic, rich potting medium like nursery potting soil (Miracle Grow, Pro Mix, or whatever you prefer) is fine and probably going to produce the most rapid growth and development.

Once you begin to reduce the size of the container, that is when you need to reduce the size of the root ball and this need the fine root ramification you get from a coarse inorganic mix like modern Bonsai soils are normally comprised of. This will eventually lead to slower growth and development/ trunk thickening... As you are most likely pruning to increase ramification, not letting sacrifice branches run, and your roots are confined to a smaller space limiting the size of the root ball and eventually limiting the length of new runners/ growth overall.

In short... For ease, affordability and expedience- you are just fine using potting soil for young trees.

The issue not mentioned is the replacement of all of the old potting soil and the introduction of a good quality bonsai mix. In some case we are back to ground zero faced with a three year program to replace one third of the old soil mix: meaning a nine year program to replace all of the potting soil with a bonsai mix. I'm not totally certain that this is a reasonable trade off.

 

[Dav4]

The issue not mentioned is the replacement of all of the old potting soil and the introduction of a good quality bonsai mix. In some case we are back to ground zero faced with a three year program to replace one third of the old soil mix: meaning a nine year program to replace all of the potting soil with a bonsai mix. I'm not totally certain that this is a reasonable trade off.

In my experience, this is not the case with shimpaku. I've completely changed out the soil in either field grown trees or potted trees in organic soil in two repots...usually within a two to three year period. The trees need to be healthy and timing and aftercare are important, but it can be done with relative ease.

 

[Vance Wood]

In my experience, this is not the case with shimpaku. I've completely changed out the soil in either field grown trees or potted trees in organic soil in two repots...usually within a two to three year period. The trees need to be healthy and timing and aftercare are important, but it can be done with relative ease.

You do place some parameters on the process; timing, aftercare and heath. If this is the presentation to beginners we have to have some sort of certainty that they, the beginners, know what we are talking about. There too is another issue; making the assumption we are only talking about Shimpaku Junipers. The way this discussion has been progressing it seems to have morffed into a concept for general development of bonsai, which would, in the beginners mind, seem to indicate every bleeding tree used in the art form, something I would not recommend with the Pine family.