So I have a Chinese elm and I tried using bonsai soil. It does not seem to be working as the water goes right through and out and it has yellow leaves from "under watering" So, what kind of soil can I use for the plant?

Thank you for your time.

I use bonsai soil for my chinese elms. Yes, the water pours straight throe. That is what we mean with free draining. However, if you water correct, thuroghly all over the surface with a fine strainer until there is a steady stream of water pouring out the drainage holes, there will a lot of water trapped in the soil.

If I remember correctly you are growing your trees indoors? Chinese elms cannot be grown indoors and correct watering is impossible indoors.

Also, are your tree in developement still?

Because if it does, maybe the Bonsai soil isn't the best choice at the moment, Bonsai soil is for Bonsai, it keeps the tree growth more under control, because when you have a tree in development you want it to grow a lot, and on a finished bonsai you don't want it to grow much, you want to keep it in shape, small internodes and small leaves...

I want maximum growth no matter stage of development and keep them under control with pruning.

Tropfrog wrote:

I want maximum growth no matter stage of development and keep them under control with pruning.

Well, Cation Exchange Capacity is a thing, Bonsai substrates have lower CEC levels, therefore holds less nutrients and water then richer substrates used to develop materials and thickening...
There's also more into that, like having thinner roots on smaller pots.

Also, granulometry is a factor Carol, when using small pots, you should use a substrate with smaller grains.

I do use smaller size. I also just added some soil with worm castings to it. I did not take it out of the pot I just added it to it with the chopstick and it is looking good and green now.

Albas wrote:

Tropfrog wrote:

I want maximum growth no matter stage of development and keep them under control with pruning.

Well, Cation Exchange Capacity is a thing, Bonsai substrates have lower CEC levels, therefore holds less nutrients and water then richer substrates used to develop materials and thickening...
There's also more into that, like having thinner roots on smaller pots.

The amount of nutrients a substrate holds is just one factor. The amount of fertilizer added is another one. If correctly fertilized our small trees in pots have relatively to the size more nutritions awailable in a year than its wild counterparts.

Tropfrog wrote:

If correctly fertilized our small trees in pots have relatively to the size more nutritions awailable in a year than its wild counterparts.

I respectfully disagree, humic soil has over 5x more CEC than any bonsai soil, and organic soil keeps nutrients levels up tru' decomposition, PLUS the fertilization...

The main point is, when you use low CEC, aereted, bonsai soil, the tree become much more dependent on you, on nutrients and water, that might make you think they're getting more nutrients.
That's why you need thinner roots in that case, so it can absorb fast the water and nutrients you give it, but research about soil leaching, which will occur on those cases...

So it's normal for more porous soils to become more demanding on you Carol, I'm glad to hear the tree is better.

Respectfully?? Should I asume there are no respect involved when that word is left out?

I do not fully see the dissagreement here. I compared the nutrients awailable to a mature tree in nature to a small bonsai relativelly their size. I have never run into deficiency problem with bonsai or on mature tree in the forest. BTW, relativelly to its size, mature trees in the forest also have more small feeder roots than a bonsai. That is to come with the less awailability of nutrients.

I totally agree that a bonsai is more dependent on you for providing the nutrients. But I do not see any big difference between organic and inorganic substrates here. The organic componds will be used up in a month or two and cannot decompose fast enough to provide what the tree needs. It needs to be added anyway. However, I prefere slightly heavier side of the organics. That is due to me not like to water every day.