Air Pruning Pots - Good for Bonsai?

Hi Jonas and Community:

Relatively new to bonsai and charging ahead with many cuttings and seedlings ready to play the long term game. Of course, I’d like to gather info to do it as fast and as well as possible.

I have juniper and Hinoki cuttings rooted and ready for transplant. Pine and Monterey cypress seedlings from last year ready to transplant. I have many species of CA native oak acorns sprouting, Douglas fir seeds and Monterey Cypress seeds in the fridge hopefully soon to come to life.

Does anyone have any thoughts or results on the air pruning type of small nursery pots pertaining to ultimate root development for bonsai nebari and trunk base flare. Any species specific do’s and don’ts?

If not, I have a batch of root pruning type pots and normal nursery pots and have started planting things out in each in an experimental fashion and I’ll be back to you in a couple of years with results.


Experimenting with container shape, size and characteristics like air pruning is good experience. It is important to understand that the container is just one variable. Developing correct root ball formation and desired shape of nebari involves many variables.
I would suggest some research on the correct repotting methods for the various species you are interested in growing. The steps you take in repotting, pruning the roots, straightening the roots, untangling etc. This activity will make a huge difference if performed correctly and at the proper intervals.

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I don’t have experience with these species so Frank’s idea of experimenting sounds like a good place to start. The containers don’t matter as much in the first year or two so the main thing will be to get as many as possible to sprout!

I have used ROOTMAKER brand air pots for more than a decade with great results. Mainly the 1 gal and express 18 prop size. They work great for keeping a fine dense root system. Be sure to have the pots up off the ground enough for air to prune the roots or like a regular pot the roots will go into the ground, or circle in a tray. Keep in mind how fast these will dry out with all the holes. The potting media Rootmaker recommends works very well, I use it for seeds and transplanted cuttings. I like the gallons for grafted JA Maple liners until they are big enough to put in the ground. I have also been using the square 2 to 6" sizes. I bought a suitcase full when on a business trip to China. They work well also but deeper than I like beyond the 4" size. I am planning to try some of these pots with Persimmon seeds which have a very strong taproot habit. When I transplant pine seedlings I cut off the taproot. This year I plan to try the rooting of seedlings method with some pines. Let us know what you learn.

Thanks for some good information everyone.

I appreciate the positivity for the air pruning concept from DWHull. Makes me feel like I could be on the right track!

On my oaks, I am already seeing roots exiting the pots, dessicating and dying back and the seedlings seem ok, although very very young still with just a couple of leaves and some without anything above soil level yet. I am hoping that the roots are branching back in the medium and doing their thing and advancing towards a strong bonsai base.

I have different soil mixes in different types of pots so I hope to get some good information to report back in the next couple years.

I appreciate the comment from River’s Edge also that I need to research specifics on how to handle and place roots during the initial repottings of young trees to stimulate nebari. This is the important step. I am on the search for such detailed information - seems a bit harder to find then simple repotting advice for established bonsai or initial repot from nursery stock to bonsai container. I’ve got some time to hunt, research and discuss with pros when I can.

Thanks Everyone…Dave

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