Title image above is copyright © Ezehelm

First published 22nd June 2025

This post arose from questions Ezehelm left — and tried to leave, poor thing! — under this post.

The commenting system on this blog is really not designed for mini-essays, and Ezehelm sent what he tried to post as a comment, to me as an email. He gave me permission to post on his behalf, and I thought it best to simply make a new post out of it, where it would be easier to read and show his pictures as well. This and Part 2 are it!

Please note: the following images are not of an Air-Pot®. The name ‘Air-Pot’ is a registered trademark and cannot be used here. I will refer to the container in question as an air-pruning pot from hereonin.

By way of background, the original comment was:

Ezehelm:
15Jun 11:26:18 PM
Reply

Hi Kristi, I'm in the tropics and am thinking of pairing up my air pot with an olla to plant golden raspberries. Thing is, I'm in the tropics. I'll be putting the plant indoors by a really tall and wide window (I live in a duplex condo) which get's direct morning sunlight till noon. And indirect afternoon sunlight. What do you think is a good soil mix for such a setup? I'm thinking:

Coconut coir – 23%
Peat moss – 13%
Perlite – 13%
Zeolite – 7%
Vermiculite – 7%
Rice husk charcoal – 7%
Vermicompost – 30%

To which I replied and asked:

Kristi:
16Jun 10:31:54 PM

Hi Ezehelm, what an intriguing idea! I 'd love to know how you go - please would you mind sharing a photo of your setup when done? And what size Air-Pot will you use?

I really like this approach to prevent it drying out, especially in the tropics by a large window!

Your proposed mix certainly had a lot of thought go into it and I reckon your raspberries will respond well to this.

Just to clarify if the coir is the fine peat coir? (Of similar consistency to peat moss.)

I've not grown berries in an Air-Pot (it's one of many many plans!), but I do grow berries, and I have a feeling that you may not want your mix to drain so much though. Berries like a lot of water especially when setting fruit - it's what makes the fruit juicy and large.

You could possibly omit the perlite and vermiculite without ill effect, as the aeration afforded by the cones plus the growing roots will minimise waterlogging. Especially with an olla only releasing water when needed.

The nutrient- and water-retaining properties of vermiculite will be more than compensated for by the zeolite, charcoal, and coir. What please were your reasons for choosing all of these? And the peat moss? Was this for pH?

Coir, zeolite and charcoal all have excellent cation-exchange properties. Coir is additionally a great material to bulk out the vermicompost and fill the Air-Pot - something you can't really do with zeolite and charcoal!

Overall I'd say this will be a great mix, though I'd personally lean towards removing the perlite and vermiculite and increasing the vermicompost - this would make the mix 50% vermicompost. A nice rich mix ready for feeding growing fruit. With the rest mostly coir filler but with the excellent properties of zeolite and charcoal there to hold and feed the vermicompost nutrients to the plant.

Attempts after this to post anything much longer ended in disaster, so please find Ezehelm’s email to me here:

Hi Kristi,

I tried splitting this message of mine into four parts yesterday and posted each of them separately, but seeing as they haven't appeared on your site today, I assume they never went through 😔

Here goes:

Thanks a bunch for the quick reply, Kristi 😊

I'll be using a 40 cm wide by 40 cm tall 46 L no brand air pot. It's slightly shorter than knee height and has a diameter of about the length of my forearm. The 4 L olla has a thin neck and a rounded flat bottom. It'll be placed in the centre of the pot. The plant will be placed slightly off centre, with its root ball touching the olla.

I actually currently have a soursop and basil planted together in this setup. I used a 6-in-1 potting soil around the edges where the cones are and the 6-in-1 plus some coarse gravel-like red topsoil towards the centre of the pot. I figured the centre would need more aeration considering the size of pot, but apparently, that's not the case, you say?

Here are some pics of the setup:

https://imgur.com/a/eqT0U1E


copyright © Ezehelm

https://imgur.com/a/mdSP3FL


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https://imgur.com/a/xdT1gEs


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https://imgur.com/a/GGqoS3O


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https://imgur.com/a/ZZppSg1


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https://imgur.com/a/QUjs7nZ


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https://imgur.com/a/A4qw2p8


copyright © Ezehelm

The basil's growth kicked off right away, while the soursop has only begun putting on new growth a week or two ago. They were repotted waaay back in February! But then the soursop's been neglected in its nursery polybag since 2022. The soil it was in (and is still partially in) was hard as heck, so the slow response isn't really surprising.

I found that the whole thing's draining the olla faster than I'd prefer. They emptied the olla in 4–5 days if I placed them away from the window and in the shade with some humidifiers (several plastic containers filled to the brim with water and some small ollas). I want the olla water to last 5 days by the window, in the sun. Do you think that's possible, or am I just being unrealistic? 😙 I'll be putting on some sheer curtains in a few weeks. Maybe it won't last that long now, but hopefully, it will soon.

This is what the setup looks like now:

https://imgur.com/a/lmUGpaf


copyright © Ezehelm

https://imgur.com/a/ndw2Grk


copyright © Ezehelm


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https://imgur.com/a/TB3Xc8I

To answer your other questions:
Yeah, what I meant by coconut coir is cocopeat. I just have an aversion to that term, since it has nothing to do with peat to my understanding.

I chose to use some peat moss just to add acidity to the soil mix. I am aware, though, that they may not wet easily after being left to dry out completely. Read that raspberries like a pH of 5.6–6.7, according to the Royal Horticultural Society and the University of Maine. Hopefully, the rice husk charcoal and zeolite won't make the mix too alkaline.

The addition of rice husk charcoal and zeolite was just my idea of increasing the mix's CEC and providing specific trace minerals which, to my understanding, vermiculite may not. I read this research paper by Chatzistathis (2001) (ikee.lib.auth.gr/record/326204/files/agronomy.pdf), got lost in all the numbers and parameters, and somehow guesstimated that 7% v/v of vermiculite and zeolite each was a decent amount.

Now I have to rethink all of this again 😅

But don't you think that using 40% compost is a bit too much? Or has that not been your experience thus far?

Anyhow, the golden raspberry' still small. It's in a pot slightly bigger than my fist, with a peat moss-based mix. It's already showing signs of overwatering (I'm really bad at watering), so I want to repot it as soon as possible:

https://imgur.com/a/yYcHjJo


copyright © Ezehelm

https://imgur.com/a/3vCo5V5


copyright © Ezehelm

Maybe not immediately into the 46 L air pot, but a larger poly bag for a few more months.

Looking forward to your advice and reply 🤗

Warm regards from Malaysia,

Ezehelm

And thank you Ezehelm, for your detailed reply and these photos! I’ll answer in Part 2, the original email way, addressing each part inline where it will be easier to follow — see you there!