Bonsai Study Group Forum

General Category => General Bonsai Discussion => Topic started by: Anthony on October 26, 2013, 11:36 AM

Title: Airpots and Colanders
Post by: Anthony on October 26, 2013, 11:36 AM
Hello to All,

I am passing on some information, hope it helps someone. As usual test on expendables.

Because of our climate - Dry Season - no rain - low humidity for almost 5 to 6 months [ this year more like 9 months] and I live in an are of 60 inches of rain yearly or so.

Wet season - humidity to 80% with the days of rain.

Repotting around Jan 2nd, takes advantage of the cooler weather, the dormant trees and no rain, so we can use up to 1/3 compost in the soil mix.

However, someone on this site, showed another pot type, an airpot, and the poor man's version, the colander [ plastic and stainless steel, coated steel.]

The airpot site on youtube, shows trees being planted in 100% compost.

So before I further yak on, we worked out a technique.

Humid air, full sun --------------- low compost in the soil mix
Dry air , full sun ---------------- high compost in the soil mix

However in normal pots, plastic and stoneware , it still remained at the bacis 1/3 organic to 2/3 inorganic [ please note we also use an inorganic that can hold moisture in itself and does not breakdown with use - no frost ]

Using the airpot - Test subject Tamarind seedlings, % of soil equivalent to a 4" x 4" X 4" POT.
Airpot outgrew the 4" pot with ease.
Around Jan 2nd next year, we will check the rooting.

With the colander, the standard soil mix, showed faster drying out, as was expected.

The Chinese are now making stainless steel colanders, with collared bases, very elegant to look at.

We are getting ready to test, 100% compost, in colanders to see how the Tamarind handles that.

Now in the 1950's a book on how to do Bonsai [ and for sale ] spoke of folding metal window mesh into rectangles and using as pots. The idea taken further, could have wire pots folded to put into proper bonsai pots.
So one could grow bonsai in colanders indefinitely and use 100% compost, as was done with the airpots.
[ please not that compost will reshape itself into roundish beads at around 2 to 3mm in size, and seen when a repotting is done.]

We noted that trees capable of growing large trunks in the ground, would produce large trunks in large plastic bonsai pots [ 14"] in about 5 to 10 years.

So you could grow a tree into a core of inorganic mix, and at the time of repotting, add back a mostly compost mix of say 1/2 to 1" if needed.

Anyhow this is just the beginning, and I will continue to pass by and show with examples, what we find.
Good Day.

This is the largest pot this Texas Ebony has even been in, and it has a 3" trunk. The extended branch is being airlayered to share out a few trees to friends. Never ground grown. from around 1980/82
Title: Re: Airpots and Colanders
Post by: Neli on October 30, 2013, 01:04 AM
I have seen in Japan they use 3 colanders one into another. Something to consider. I am going to try the mosquito mesh makeshift growing pot. I want to see how it will work.
Title: Re: Airpots and Colanders
Post by: Anthony on October 30, 2013, 10:45 AM

there are times when the Muse smacks you over the head with her hand and ideas start popping in at a tremendous rate.

So if one could grow trees in 100 % compost, well made compost, how much compost would be equal to x feet [ x m ] of open ground? [ Airpot Youtube idea ]

So you develop your bonsai in a small colander with a mix of inorganic and organic, then when the time is right place that container into a say 8cm [ 3" ] larger colander, rich in compost, and if needed some coarse inorganic material [ say 10mm ]
Then at a later time in the year if able another colander larger by [ 8cm /3" ]

The idea being that the compost is what the tree's root evolved to use. Weak mixes of less than 5N 3P 3K plus micro nutrients, can be given as needed.
[ I am not a great believer in Hydroponics nor the vitamin/mineral suppliments humans use as we did not evolve to use them as such, fresh fruit, vegetables [ Chinese cooking style preferably .]]

Wish I could calculate say the nutrient avaiable in 3m x 3m x 1.5 m deep of rich ground growing soil, to see how much compost would be the equivalent.
Anyhow thanks for the idea oh Muse N.
Good Day
Title: Re: Airpots and Colanders
Post by: Neli on October 30, 2013, 10:57 AM
If you noticed, the inner colander has bonsai mix, and the outer dark soil/compost. You have the benefit of having fine roots inside the first colander, and better food outside, that is also able to keep the inner part from drying too fast.
Just that as far I know if there is more than one colander, when repot is done all outer roots are removed.
Title: Re: Airpots and Colanders
Post by: mumra on November 07, 2013, 11:40 AM
Ok first post here  :o.. be nice  ;)

I would use colanders for growing but can't find them cheap enough so I use pond baskets which come in at a fraction of the price plus come in a multitude of shapes and sizes. These work extremely well although likely won't last as long as a colander.

I have found the benefit of using them is they give a nice fine root ball with lots of feeder roots due to the constant 'automated' pruning of the roots when they hit the light and air outside of the pot.

I tend to use a mostly inorganic mix as I can control the feed much better, and can feed harder. One thing you do need to take note of is if the pots are drying out, especially on hot days, as the soil is pretty much open on all sides so sun/wind can dry it out very quick. I will add that this is not really a problem for me as I am in the UK and any sun is a welcome surprise  ;D

Just my 2 pence/cents
Title: Re: Airpots and Colanders
Post by: Neli on November 07, 2013, 12:26 PM
Pond baskets are the same as colanders. They do a good job. You can bury them n the ground or keep them the ground is faster growth.
Title: Re: Re: Airpots and Colanders
Post by: Joshua Hanzman on November 07, 2013, 08:10 PM
Rootmaker is a really cool product although you've probably heard of it before. It's a pot shaped pliable metal mesh (think the material windowscreens are made of) in which the mesh edges are sharp, a tree is placed in this and grown in the ground. The sharp edges make it so any large root is immediately cut off after it reaches a certain diameter, however the tree gains all the benefits of growing in the ground, but no roots every reach a design damaging thickness. I have seen some fantastic results at a friend's nursery, I noticed that his material was far better suited for bonsai than most other non-bonsai nurseries and I wondered why. I believe it has to do with this rootmaker, which is basically trimming any non fibrous roots right off, but allowing feeder foots to extend and nourish the tree. And when he sells a tree, he takes a shovel to the outside of the rootmaker and removes a perfect rootball every time!
Title: Re: Airpots and Colanders
Post by: Anthony on November 08, 2013, 04:35 AM

I did some reading and looking. On youtube there were complaints from 3 years ago that Rootmaker copied Airpots.
I liked the screened bag idea.
If you pop down to Ausbonsai, you can see the colander in use and how he lifts the container every year to handle the expanding roots.

The colander is popular simply because it is cheap. On my side we get stainless steel woven mesh colanders with lifted bases for only $3.00 US. about 10" across.

Will let you know how it all went.
Good Day

Airpot as it was earlier this year. Tamarind
Title: Re:
Post by: Joshua Hanzman on November 08, 2013, 05:05 PM
In bulk the rootmakers are cheaper than three dollars, also, i looked into what you said and it looks like the one product is similar to air pot. But I'm talking about the other product the one for ground growing, there is nothing like that on, the reason i think the root maker has added benefit over airpot is you can grow root maker above ground and also no roots curl. Or you can grow it in the ground and get monster plants but no large roots or curl. I have seen the nicest nebari I've ever seen in my friends nursery box woods, full turtle back from the root maker. I'll post a picture later to explain what i mean...

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Title: Re: Airpots and Colanders
Post by: Anthony on November 10, 2013, 07:44 PM

another variation on the colander [ remember colanders also come in stainless steel, woven mesh ]

The smart pot - Smart Pots (

Smart Pot Growing Method and Advantages (

I bought 2 to test from Amazon.
Good Day
Title: Re: Airpots and Colanders
Post by: Joshua Hanzman on November 10, 2013, 11:45 PM
Very cool, I see the advantages to growing in this manner, I hate when a nebari has a circular root, such a deal breaker for me!
Title: Re: Airpots and Colanders
Post by: Joshua Hanzman on November 11, 2013, 12:37 AM
I do realize now we are talking about different but related topics, completely my fault :/

 You are air-growing, not ground growing. The advantages (I think) that rootmaker provide are best exemplified in ground growing, as rootmaker-grown material has a good compact rootball, balanced similar sized roots, but has the added benefit gained from ground growing. Another advantage over general ground growing would be the fact that due to the constriction root pruning, the cyclical examination of the roots and subsequent pruning to avoid unbalanced nebari would not occur.

I will try both methods on similar stock in spring and see how that goes. I would think a big advantage of airpot growing is if ground growing was impossible. Furthermorw, young stock could probably be placed in a large airpot; however young stock could not be placed in a large regular pot, as the capillary actions of water would cause it to drown. I would think (but am not sure) that this would be avoided by using an airpot as the airpot is not constricted on all sides and so water would not be held in...

This is rather important for me because a lot of my stock is going to be grown in whatever method is most efficient.
Title: Re: Airpots and Colanders
Post by: Anthony on November 11, 2013, 04:06 AM

see if you can imagine this. Using a stainless steel colander of say 8" diameter, with a bonsai mix, you grow the tree until you know the roots have mastered the soil mix, and filled every spot in the colander.
Then you place the colander into the air-pot or smart pot, filled with either 100% compost or a rich mix.

The idea being that the compost is as rich as say roots searching through 10 x 10 feet of ground.
So you have the colander, in say a container about 2 or 3 " larger than the colander.
Plus the air-pot or smart pot is also pruning the roots.
Good Day
Title: Re:
Post by: Joshua Hanzman on November 11, 2013, 11:43 AM
Oh ok ok, I see what you mean, will the colander have reusability or get broken by roots?

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Title: Re: Airpots and Colanders
Post by: Anthony on November 11, 2013, 12:36 PM

the colanders we got are stainless steel, and we will check at the end of year for the root situation.

The plastic colanders, that were in the ground, were also covered along the rim, this prevented the UV from destroying them.In our sunlight, they probably wouldn't last a year.

So we are also looking at the stainless steel screen, used in the oil industry, and making containers [ nothing new, it was being done back in 1950, out of window screen ] to hold the stainless steel colanders.
Good Day