Does bonsai soil mix drain water to fast for pre-bonsai plant

Ramman

Yamadori
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St Augustine fl 32086
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9B
When buying from big box stores and nursery’s for bonsai, would repotting them in bonsai soil retain moisture long enough for them to mature. My mix is 40% pumice,40%% calcined clay and 20% pine bark fines. Not so sure?. Help!!
 

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If you're watering properly then it doesn't matter if a tree in early development is in the soil you described.
That said, most of us save the good stuff for later or when we're specifically working on root/nebari development. If it's in a nursery can or big grow out pot, we often go with cheaper soil (heavier on the organics) just to save money and worry. Why invest either before the tree is note worthy?

I guess the better way of putting it is this: what sort of container is it in?
The purpose of the free draining substrates is because small shallow pots don't like to drain very efficiently. Remember that gravity is what causes the water to move throughout the soil, and the roll gravity plays in drainage is a function of vertical distance. More vertical distance, easier drainage; less vertical distance, slower drainage. Therefore a shallow pot need help draining, so we use coarser, harder materials as substrate.
 
A variety of soils will work for bonsai and pre-bonsai alike — but it’s generally not going to change much with regards to their growth and maturity. You gain more control with bonsai soil and promote good root structure and ramification between repots. It also limits the possibility of overwatering. But in terms of plant size, it’s more about room for the roots to grow and energy gained from sunlight.
 
Quick clarification on your word usage. Many plants enjoy fast draining soil as sitting in water-logged soil prevents oxygen from getting into the roots. Swamp species are an exception. I think you are asking about the substrate drying out too fast.

Now to answer the question on if it drys out too fast: It depends.
Depending on how you water, transitioning into a free draining substrate early on can be helpful. That way the core of the root ball has a substrate that is free-draining and matches closely to whatever it will be surrounded with in the future. Once a tree has matured (in our case moving into a refinement state or very late development), you'd want to leave the root ball and core as intact as possible.

A smaller particle size of your substrate will retain moisture for longer as well as adding a higher percentage of organics (of the same particle size). My saplings and seedlings are in extra fine particles to achieve maximum airflow and moisture retention. Is it necessary? No, but I have a habit of watering more then I should. A potting soil for me will stay too wet for too long.

@ShadyStump and @Dogestoevsky also make good points about the pot size and height being of importance. Another point to think over in your pot selection as well, roots grow towards moisture. So if you have a nursery can with a free draining mix, the top will dry out a whole lot quicker then the bottom as the gravity column holds some water down there. The roots will grow down towards it. This can lead to some root balls that will need drastic pruning over the years to keep encouraging horizontal root expansion. A thinner and wider pot can help with our root goals (Such as Anderson Flats or seed trays).
 
Ah, you have stumbled into perhaps the deepest of all rabbit holes within bonsai, the dynamics of soil and all it’s complexities. Some meta-advice, on a slightly different track than the other commenters so far: Keep it simple, stupid.

When I say simple, I don’t necessarily mean in terms of the actual soil components or how it functions in the pot, nor do I mean the considerations of when to use what soil components in what quantity. I certainly don’t mean trying to save trouble by skipping out on part of the process—not sifting to size or not even repotting at all. Instead, I mean that it’s useful to minimize variety and variance in your soil. Pick something (ideally something that the local enthusiasts also use) and run with it. Observe how the choices function and whether it works for you, and go from there.

For me, I apply the KISS principle by keeping my main mix to just two high quality components, pumice and akadama. I also use a young plant mix of pumice and coco coir, which I have observed to function differently in some key ways over just this repotting season.
 
If you're ready to do some real spelunking in this rabbit hole, check out this resource.

It gets pretty heady for us non-geologist types, but once you start wrapping your head around the gist of it you're pretty well good to go. Matching things like CEC and pH to the water retention and drainage part and then matching that to the particular tree and your climate; it all becomes a never ending game. You'll figure out how to play it over a few growing seasons.
 
I'm going into my third year in the hobby, but year two was completely left to just let things grow and work on my actual home garden for my new home. Year one was me asking questions I could have probably found on the forum, and being about as psychotic of a nursery and big box hunter as the rest are when they start. I killed one large spruce, a nice procumbens specimen, and a small baby mugo. RIP.

Since I don't have one single tree in a proper bonsai pot to this day (except for a specimen I bought at natures way), what I've found to work for my not so OCD, but getting there, watering habits is just a nice organic potting soil with barky bits that I amend with additiinal small pine chips. I know what I do is probably frowned upon and do want to get I to the weeds about soil chemistry this year, but I've done what many recommended early on, which is to learn to keep trees alive, learn about their specific needs, be patient, and don't chop every tree up into what you want your final tree to look like when you get it out of the car.

That said, if it were me, I'd get two of the same pieces of nursery stock, amend them with an organic potting mix and the other with akadama/pumice, and see how both fare for you entering next season or more. Might be a fun experiment, and I'm sure you'd glean quite a lot from it. Would be a fun thread to watch, perhaps. Good luck.

Chris
 
My development mix is 30% coco peat, 40% large grain perlite, 30% coco bark.

The stuff is really cheap with the bricks and bags you can buy off of Amazon.

Of the developing trees that I have watered daily, the ones doing the best right now are in mostly organic soil (amended as mentioned above to drain faster). The particles hold onto enough moisture for the roots to suck it out without rotting in a column of water.

I actually had to repot two cypresses and a juniper because the off the shelf calcined clay bonsai mix was draining so f*cking fast, I had to use a ton of water just to get it to uptake and stay hydrated.

This problem would only have gotten worse in the Georgia summer.

Grunge
 
My repotted pre-bonsai are in 50/50 organic soil and pumice mix that I prepared. Upon the next repot the pumice will increase as more soil is removed from the core. The final repot will be akadama, lava rock, pumice.

My smallest junipers in akadama, lava rock, and pumice (terra cotta and bonsai pot) require water nearly every day as temps are rising and days lengthening.
 
Most of what is said above doesn't really matter to you!! What you have to determine is what works best for you and the plants you are growing. Your location, your time availability, your water quality, the material you are growing and many other factors all combine to make your situation unique to you. All these other folks have different situations than you and that has to be considered in what advice you choose to follow or not follow. Looks like you are in FLA so advice from outside your area of the country will likely not be effective for you. Given your location, chances are really good that you could grow in total organics and you would never have an issue...do that in a different area of the country and the results would be different.

The bottom line is YOU are the only one that can figure out what works for you and your plants. Be observant, if your plants wilt frequently you need to change how you water or the composition of the soil... If your plants stay wet for days at a time, you might need to rethink your soil. Just remember this one thing...if your plants aren't thriving and vigorous, it will be challenging to be successful in this hobby.
 
Newbies tend to be reluctant to "pay money for dirt," so the mantra is "Drainage, drainage drainage!" However, you can get by with poorly-drained soil if you adjust your watering and fertilizing schedule accordingly. It's harder for most people to water several times per day if their mix is draining too well, since most people have jobs (or school), so it's sometimes good to err on the side of having soil that's a little bit too wet. One caveat is that if you receive a lot of rainfall, it may be difficult to keep a poorly drained soil from staying too wet.

Using the same soil, a deeper pot will drain better than a shallow pot. It's counterintuitive, but it's important to know when choosing a soil mix. In practice, that means you can get away with using a very moisture-retentive soil in a deep pot, and that means you won't need to worry about watering as often. Your patio plants in a peat-based mix in large terra cotta pots will have plenty of water in reserve, so they can go a week between waterings. Because flower pots are much taller than bonsai pots, they also get enough air, even though the soil holds lots of water. Thus, ordinary potting soil holds too much moisture for most bonsai trees, but it works well enough in deep pots to meet the needs of your average lazy gardener.
 
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