Does a really big pot need a different soil consistency?

[Gonzoe]

So I live in an apartment with a nice sized balcony, no yard at all. I have a big pot about 2ft wide and like 2.5ft tall that we currently use for flowers, but my wife no longer cares for them lol My question is, do I need to change the mix of soil if I were to use it for letting my bonsai grow bigger? Will it retain water longer, shorter, etc?.. Any body have any experience with this?

 

[Paradox]

Potting soil will probably stay too wet for a tree, especially pine or juniper. It's deep but 2 foot x 2 foot really isn't a lot of area. You're probably going to be able to fit no more than 2 trees in there at a time if that.

 

[MGTT]

My limited experience is watering is a big issue when trying to ‘oversize pot’. I thought it would simulate inground, but it definitely doesn’t.

There are many comments on here regarding that, and they’re right on.

If not inground, the pot should only be large enough to hold it for a couple of years before repotting (if you do a search you’ll get more details, but regardless of soil, simply up potting doesn’t really work well)

I’ve been transitioning my trees to just slightly larger pots, and that’s worked much better for growth and health.

But, unfortunately, it’s nowhere near the growth I get for the few inground trees I have.

 

[rockm]

The bigger the pot the bigger the root masses on trees that are in it should be. Potting soil has no place. It doesn’t drain. In a pot that large it will be swamp. Unless you’re growing g bald cypress it will be a death trap for most any tree you put in it. Bonsai soil is best. It drains

HOWEVER the large soil mass will remain wet in pots if there aren’t roots to take up the water. If you plant small trees you will likely lose them to root rot

The pot size for bonsai should roughly be an inch or so larger than the root masses all around. That reduces the volume of soil and maximizes the roots ability to take up water and. I’ll use the empty spaces

 

[snowman04]

Put a nice shrub in it and call it a day...

 

[Gonzoe]

It’s not potting soil, I think I didn’t word myself right. It’s lava, akadama mix. I’m just asking if you need to change the ratios. That’s the right way to word it lol

The bigger the pot the bigger the root masses on trees that are in it should be. Potting soil has no place. It doesn’t drain. In a pot that large it will be swamp. Unless you’re growing g bald cypress it will be a death trap for most any tree you put in it. Bonsai soil is best. It drains

HOWEVER the large soil mass will remain wet in pots if there aren’t roots to take up the water. If you plant small trees you will likely lose them to root rot

The pot size for bonsai should roughly be an inch or so larger than the root masses all around. That reduces the volume of soil and maximizes the roots ability to take up water and. I’ll use the empty spaces

 

[River's Edge]

It’s not potting soil, I think I didn’t word myself right. It’s lava, akadama mix. I’m just asking if you need to change the ratios. That’s the right way to word it lol

Changing the soil mix is done to vary the moisture retention and CEC capacity depending on the needs of the tree or maintenance routines preferred.
Your climate and specific variables like balcony, sun exposure and wind protection will also play a role in determining the best mix in your situation. Particle size is also a factor. I. would suggest a basic mix of equal parts Akadama, Pumice and lava as a good starting point. If that mix remains too wet reduce the Akadama, If the mix is too dry add a higher percentage of Akadama. Begin with a medium size particle mix as a good starting point.
No one can give you the correct mix for your application, One needs to adjust for ones situation.
If you know the type of tree you wish to grow and its general stage of development further suggestions may be offered to assist. For example Pines like it drier and Maples like it moister.

 

[rockm]

It’s not potting soil, I think I didn’t word myself right. It’s lava, akadama mix. I’m just asking if you need to change the ratios. That’s the right way to word it lol

No. Don't really have to change ratios (note the differences for species though). The soil volume thing still applies. Larger soil masses remain wet longer, particularly in areas with no roots to take up the moisture, so small root masses in a large volume of soil will have issues.