Zeolite - What size?

[TamworthSteve]

Hi All,

I am getting back into bonsai after a few years of not having time/motivation etc. A LOT of my trees didn't make it due to lack of care/watering, so I am forced to begin again, with the exception of a few trees who's roots were able to escape their pots into the ground.

My plan is to use a good quality potting mix in black plastic grow pots for the first few years until I have something that is displayable.
I'll be using the Searles Premium Advanced Potting Mix, 65ltr for $22.55.
I'd like to add some zeolite to the mix for a few reasons, to make it go further, increase drainage to prevent root rot etc.

I have a zeolite mine within an hour's drive from home, and they offer a few different sizes, the two I think would be most suitable would be either 1-2mm, or 2-4mm.

Would one of these be considered the 'best' size?

And how much should I look to add into a 65ltr bag of the above commercial mix?

Again, this is purely for black plastic pot growing of young trees and pre-bonsai stock, not refined stock going into a small bonsai pot.

Many thanks, in advance,
Steve.

[Dendrophile Dave]

you cant go wrong with either of those sizes really. Add 10% zeolite : 90% mix, the main benefit of zeolite is its cation exchange capacity CEC which helps holds nutrients for the plants to use rather than them going down the drain. Also I'd recommend Scoria as a good relatively cheap potting mix additive, just test each batch as it can be highly alkaline. Also hydroponics shops are great for all sorts of mix additives such as perlite, coir,etc
good luck

[NikiC]

Personally id go the bigger size 2-4mm to improve drainage and air exchange etc.

[kcpoole]

I add 20% zeolite ot my own Akadama, Pumice Zeolite mix.
1-7mm pumice, 2-6mm Akadama and 2-6mm Zeolite

Ken