100% pumice air layer?

[Cruiser]

Has anyone successfully air layered a tree using only pumice?

If it encourages root growth and gets used often for freshly collected material wouldn’t that point to it being effective for layering?

The smaller particles (1-3mm) seem to retain a lot more water compared to larger pieces, and also drains nicely.

Why/why not?

 

[Kanorin]

Good idea! I might try it out this year.

 

[JackHammer]

Just seems like you would need to water constantly.

 

[BrightsideB]

I would think adding some perlite would be good. A size that matches the pumice. I did this with growing pines and it actually worked well. And mycelium filled the whole container within two years.

 

[Wires_Guy_wires]

I've done some cutting trials and pumice came out OK, but not the best. The best was still sphagnum moss, coco coir came second and third came akadama. Pumice was just below perlite.

 

[andrewiles]

I've done it. It works, just doesn't seem to offer many benefits. As @JackHammer says it dries out really fast and requires more maintenance. I've found that an 80:20 mix of perliteeat stays light but retains more water and adheres together better. The small diameter pumice can get quite heavy after watering, which may require additional support. Perlite just seems all-around better in that regard, even if you wanted to go perlite-only.

Personally, I've shied away from sphagnum moss because I've had trouble getting it out of the roots later. The other mixes fall out easily if the layer is dipped in a bucket of water.

 

[cbroad]

I've found a mix of 50/50 perlite/chopped sphagnum works really well for air layers, and is super easy to clean out before potting up.

 

[vp999]

What about just 100% garden soil ?

 

[River's Edge]

Has anyone successfully air layered a tree using only pumice?

If it encourages root growth and gets used often for freshly collected material wouldn’t that point to it being effective for layering?

The smaller particles (1-3mm) seem to retain a lot more water compared to larger pieces, and also drains nicely.

Why/why not?

I have used straight pumice with shredded sphagnum moss for airlayers with regular success. I use a smaller particle size that is sifted free of fines.
Variety of species involved, juniper, tskumho cypress, Beech, and black pine to name a few. Currently using the same mix for JWP to try and get them on their own roots. So far the JWP trees are doing well after one season. I expect that it will take two full seasons for successful root formation with the JWP. That was the time frame for the other pines.
I started to use small pumice for cutting propagation of species with sensitive roots. The combination with sphagnum shredded made it easier for me to comb out new roots for radial formation when transplanting successful cuttings. I just expanded the use to air layers and found it useful. This is a picture of the pine I successfully air layered with pumice.

 

[jeremy_norbury]

I hate it when they only root on one side...

 

[Johnnyd]

Yes I layered a maple in % pumice with sphagnum on top. It worked but it was obvious the roots preferred the sphagnum moss. The roots gravitate to the moisture.

If I need to separate the roots from the substrate in the same season I've used akadama (ie.for a root over rock project). It's easier than picking out the moss.

If you are set on using pumice I would take River's Edge's advice and mix in chopped sphagnum.

 

[River's Edge]

I hate it when they only root on one side...

I do too, fortunately this one had roots all the way around, just heavier on one side. By the time I removed the bottom stub in the next go around the root formation was fine. Bonsai simply takes time and often several stages for better results.