…is full of sweet birdsong and rainbows.
I feel the need to comment on Turface, which is still, unfortunately, a common bonsai soil component. I say unfortunate as this is one of the worst soil components you could ever use.
I will not go into the soil science of ion exchange or things of that nature. Given the evidence from the trenches, it hardly matters. My experience witnessing root development in many types of soils has confirmed that Turface ranks dead last. (Oil-Dri and Profile are equally bad.)
There are two obvious faults of Turface. The first is that it produces some of the most anaemic, thready root systems that can be had for any money, and secondly it has a deadly hydrophobic property when dry. How many of you have just watered a tree planted in Turface, scratched the surface of the soil and found it to be bone dry underneath? For the ‘No’ answerers, I hope you never have the pleasure. This dangerous property will result in dead zones in your soil, creating a situation where the majority of the roots will grow in the worst places in the pot, which are along the sides and the bottom. The main problems of Turface may be summed up this way:
- Hydrophobic properties lead to unpredictability in water penetration
- Turface either stays too dry or too wet, and so it is not able to create a middle moisture level that enhances root growth
These problems are severe, with this conclusion:
- Root growth in Turface is erratic at best, without the benefits of predictability seen in volcanic soils
Given that the foundation of the tree is the roots, and that bonsai training is by nature stressful to the tree, having a marginalized root system is to be avoided at all costs. You don’t have to use akadama. But at least don’t use Turface, and you won’t experience random, poorly ramified root structures that cannot support bonsai training. There are many things that can work, but I will say that pumice is a near-perfect particle for fine root growth.
I know many of us use Turface out of habit or availability, and can understand skepticism of this post. Maybe you’ve not seen what I’ve seen. I do get around and see a lot of soils. But at the end of the day, roots are not something to be taken lightly, for having an excellent root system is so much more important than owning fancy, expensive bonsai tools, expensive fertilizer, expensive pots, or even expensive trees. Buying cheap or easily available soils simply because they are cheap and easily available will make all of that magnificence entirely moot. In bonsai, a finely ramified, healthy root system is everything.
If you have some Turface, don’t ‘use it up’ by adding a small proportion to your mix. Give it away. Pay someone to find a use for it. Or put it in a box, label it with an unknown address, and offer it to the post office. It’s safer there, wherever it ends up, than in your bonsai pots.
PS—Not long ago I resisted teaching or writing in an emphatic manner, to avoid upsetting people or to avoid arguments. But much like the concerns offered in my post Never Pinch Junipers!, I see so many weakened bonsai as a result of using Turface, Oil-Dri, and Profile that I have to speak. My main loyalty is to the trees. This is one area where cutting corners is really not the best way to go. Spend money on soil. If things like pumice are not readily available, get it shipped and split the cost with friends. It’s not the lightest thing on the planet, but then thankfully it’s not lead, either.