Author Topic: experimenting with clay soil in containers  (Read 722 times)

brian

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experimenting with clay soil in containers
« on: October 30, 2022, 09:41:46 PM »
Since moving many of my citrus and other container fruit trees into wide, shallow containers the two issues I am running into are

1) trees dry out quickly on hot days, which is expected
2) stability is a major issue at first when repotting into a shallow container.  I end up having to use strings, sticks, weights, etc to keep them from flopping over, especially when they are loaded with fruit

So, against all conventional wisdom, I am trying something which helps solve both of these issues - heavy clay.  My native soil is clay, I like to optimistically think of it as clay-loam but it is truly terrible when it comes to drainage.  When wet it forms a thick mud that will pull your boots right off if you step in it. 

Because I have recently been replacing my overly vigorous in-ground citrus trees with grafted-onto-flying-dragon clones, I end up with extras I no longer have use for.  These extras become subjects of sometimes cruel experiments. 

While repotting a half dozen trees today (into containers 3-4in deep), I added increasingly large amounts of clay soil to the usual free-draining mix.  The last few received almost entirely clay.  I watered them and a half hour later they were still saturated mud, I didn't keep waiting to see how long it would take to drain fully.  The heavy soil definitely helps keep them upright without outside support.

My hope is that the clay soil will be acceptable for these wide shallow containers, my reasoning being that I can control how often they receive water (because they are greenhoused) and because of the shallowness they may still receive enough oxygen from the air, and the plants transpiration plus air evaporation will keep them from becoming stagnant.  Trifoliate Orange is supposed to be one of the better rootstocks for clay also, I have read. 

Why go through this trouble to accomodate atypical containers?  It is mostly that I like the appearance of the tray style trees, that it eliminates the aggravation I have with discovering cylinder-pot trees have large dry spots or overly wet soil deep in their container, and that it lets me hang them up in the air without constantly hitting my head on the bottom of the pots. 

My in-ground in-greenhouse citrus trees thrive in this soil, but they have no perched water table.  I will report back how things work out. 
« Last Edit: October 30, 2022, 09:55:44 PM by brian »

1rainman

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Re: experimenting with clay soil in containers
« Reply #1 on: November 02, 2022, 05:55:39 AM »
Citrus doesn't like soggy roots. Trifoliate I don't know it's from a different climate.

Citradia

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Re: experimenting with clay soil in containers
« Reply #2 on: November 02, 2022, 06:56:06 AM »
Trifoliata performs better when not in clay or soggy conditions. When I changed from regular potting soil to 50:50 mix of Turface and Miracle Grow Garden Soil, my poncirus seedlings started  growing very well. I fertilize with Osmacote and miracle grow. From your pics, what you’re doing is Bonsai with a fruit tree. According to my bonsai books, when making bonsai out of fruit trees versus non-fruiting trees such as pine, you need a deeper pot to accommodate more root mass, especially when first starting a specimen to help build trunk caliper. You need more roots to sustain fruits. They make bonsai soil you can buy pre bagged. Probably get it online. I used to be a member of the bonsai society in Gainesville FL. A local bonsai group may be resourceful for you.

Millet

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Re: experimenting with clay soil in containers
« Reply #3 on: November 03, 2022, 12:09:47 PM »
I have been using 5-1-1 medium for a long time.  It is a good medium. About a year ago I potted a tree in 50:50 mix of Turface MVP, and peat and I totally agree with Citradia, it is an outstanding medium.  Going forward as I repot my trees, all will be switched over to the 50/50 Turface/Miracle Grow Garden Soil mix.

poncirsguy

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Re: experimenting with clay soil in containers
« Reply #4 on: November 03, 2022, 11:06:28 PM »
If I used Turface/MG for my 30 gallon trees I would go broke.

cassowary

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Re: experimenting with clay soil in containers
« Reply #5 on: November 05, 2022, 01:09:49 AM »
The clay will most likely work for you since it will hold nutrients quite well compared to some of the gravel peat based products. The ECEC will be better in the clay. So the fert you put on will last longer unless it gases off or form strong chemical bonds etc.
I use clay in all my potting mixes as this also increases water holding capacity as you say. And it's good to let the potted plant be used to you native microbiome if you ever wish to transplant it in the ground.

It's unfortunate so many nurseries use gravel peat mixes. Transplanting these are a nightmare with all the medium falling off, clay holds it together.

And yes I also noticed that more clay increased the weight and reduced falling over of the tree.
I think clay helps to create a more sustained environment moisture, nutrients, orientation (less falling) etc.
For seed and plant swap/barter enter “tropical seeds” @ https://publicnote.com/

orangedays

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Re: experimenting with clay soil in containers
« Reply #6 on: November 05, 2022, 10:18:28 AM »
I had the idea last year to add clay to increase water retention, take advantage of clay's ability to hold on to ions, keeping nutrients available and to increase iron as my trees were showing iron deficiency.  I potted many trees into a mix containing 10% red clay.  It was a total disaster.  The citrus on PT root stock and natural roots started to die with-in months. I re-potted all the citrus. Of course in a dry environment it may not be as detrimental.

The other plants vegetables, flowers, etc. were very happy in the clay amended soil and grew very well.  I don't rule out it may have been the clay I used. As Brain noted, the PT trees growing  in the ground do well in heavy clay.  I have a large healthy citrumelo growing in clay you could use to throw pots and feral PT trees colonize  creek banks where its both wet and full of heavy clay.  So there may be role for clay.

1rainman

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Re: experimenting with clay soil in containers
« Reply #7 on: November 05, 2022, 03:48:42 PM »
It would be better to use rocks, sand etc which will be heavy but have good drainage. I put a small amount of clay in my potting mix. Maybe 5% or 10% at most. This keeps it from drying out but pure clay is not good. Of course dirt from the ground probably isn't pure but is not a good choice for citrus. Most plant love to be wet but citrus does not. Mulch also is not good on citrus most of the time because it stays too damp.

brian

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Re: experimenting with clay soil in containers
« Reply #8 on: November 05, 2022, 08:50:53 PM »
I very much understand that clay is likely to be detrimental in normal circumstances, and I am willing to lose these trees, but this experiment is entirely about "how little container soil volume can I get away with?"

For stability, yes rocks would be fine, but these trees are trying out too quickly and rocks have no moisture holding capacity.

Worst case, these trees decline and the experiment ends. 

poncirsguy

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Re: experimenting with clay soil in containers
« Reply #9 on: November 05, 2022, 11:58:34 PM »
Brian  great idea.

W.

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Re: experimenting with clay soil in containers
« Reply #10 on: November 06, 2022, 01:37:25 AM »
You'll never find out if you don't try. That's what experimenting is all about. I hope your trees thrive in their new medium. Your posts on growing citrus in shallow containers has certainly given me ideas for future experimenting of my own.

pagnr

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Re: experimenting with clay soil in containers
« Reply #11 on: November 06, 2022, 04:20:53 PM »
I have used fired kilned clay in pot mix, ( attapulgite ). Brick clay beads are common in Hydroponic shops. Bentonite clay is common in Cat Litter as nice sized particles, but it dissolves and can clog pore space in pot mix.
I have thought of firing native local clay to make pot mix particles, or use broken red brick grit etc.
There might be clay shrinkage in your soil experiment, ie wet expansion / dry shrinkage in the pot. The Media might move away from the walls and the free drain ?
Have you thought of trying Hydroponic type pulse irrigation on your shallow containers ?

brian

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Re: experimenting with clay soil in containers
« Reply #12 on: November 06, 2022, 11:57:12 PM »
Pagnr, fired clay has very different properties than the "dirt clay" I am using

pagnr

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Re: experimenting with clay soil in containers
« Reply #13 on: November 07, 2022, 01:14:23 AM »
Pagnr, fired clay has very different properties than the "dirt clay" I am using.

Yes, it has most of the clay benefits of water holding, cation exchange, weight etc but with a permanent structure.
!00% pot mix of  fired clay would not be as water holding as clay soil.
Maybe very fine fired particles would be a compromise.
I have grown vegetables on a few acres of grey clay river flat soil in the past, so aware of clay solis.
There was a brick works not far using the same clay for red bricks.
Keep us updated on the project.

1rainman

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Re: experimenting with clay soil in containers
« Reply #14 on: November 07, 2022, 03:06:59 PM »
I use cat litter. Though if I had clay soil I'd just use 5% of that. Only because summer time it's so hot I have to massively water every day and it's bone dry the next day for any plant that fills the container. But I can't go overboard because in cold weather or rainy season it might get water logged. This small amount of clay in the potting soil seems to work well.

brian

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Re: experimenting with clay soil in containers
« Reply #15 on: November 08, 2022, 10:17:17 PM »
I had assumed fired clay would have far less water retention than raw clay.  I used to have cats long ago and I remember the litter would distintegrate easily, not like turface or hydroton.  I am not sure what it is made of but it might be halfway between the two

pagnr

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Re: experimenting with clay soil in containers
« Reply #16 on: November 09, 2022, 04:40:45 AM »
Cat litter could be Bentonite Clay. There is a mine near here.
I think unfired  Attapulgite might also dissolve in water, so could be an alternative. Also Clay is used as BBQ grease cleaner for spills on concrete areas.

citrange

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Re: experimenting with clay soil in containers
« Reply #17 on: November 09, 2022, 04:34:12 PM »
For several years I have been using a mix containing 50% 'danish Molar Clay'. This is sold in UK as some cat litters and also as a spill-absorber. The producer in Denmark is https://www.imerys.com/minerals/moler

 

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