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After  plugging the drainage holes in another batch of  terracotta pots I have embedded  them in my garden beds. Sealing holes in terracotta is not as easy as it may seem. You need to check to see if they sweat rather than leak. Watching beads of moisture form on the outside of  the terracotta  for the first time is  a thrill. 

To then entomb them in situ is like making an offering to the soil.

With over 50 pots in place in my garden -- standard plant pots and terracotta wine coolers -- filling them is now a routine chore.  I suspect that if I stiffen the end of the hose by wrapping a rod to it topping up each pot will be easier and I won't have to crouch down so much. 

But each time you visit a pot station I get to inspect local ecology.

Instead of using tiles I'm now preferencing heavy white dinner plates I get cheap at Op shops as lids atop the pots. Facing up they sit snuggly on the pot lips and the white stands out in the garden beds. As the plants grow and more mulch is scattered on the beds you need a marker to find the pots when refuelling otherwise they get hidden.The snugger fit offered by the plates  makes it harder for crows, passing canines or escaped chooks to displace the lids. If a lid is ajar there is more evaporation, and mosquitoes or cane toads will move in. The white plates also reflect heat and reduce evaporation.

Even though my newer  pots are mass produced Italian imports not all pots are equal and the sweat rate varies probably because of the clay mix and idiosyncratic  effects of firing times. The rate at which these pots drain  is dependent on variables I don't, as yet, understand.

If the soil is already wet they'll drain faster than if it is dry. Where pots have ' settled in' and the local soil and flora have adapted to their presence there is remarkable plant growth compared to non-pot places which are water neglected. But the interaction takes time -- maybe weeks-- to consolidate so it is not like hosing a garden bed. This is a subtle almost passive irrigation process driven by  gravity but facilitated by the plants themselves, the amount of soil carbon and biota .

The slow release is ideal for my sandy soils as all other approaches I've used ended soon after I stopped watering as the water would drain away into the aggregate below each bed.

Research done by the University of Pretoria in South Africa confirms how effective these pots are in reducing water usage.

The clay pot used for irrigation is an unglazed indigenous earthen pot which has many micropores in its wall. The microporous wall does not allow water to flow freely from the  pot, but guides water seepage from it in the direction where suction develops. When buried neck deep into the ground, filled with water and crops planted adjacent to it, the clay pot effects sub-surface irrigation as water oozes out of it due to the suction force which attracts water molecules to the plant roots. The suction force is created by soil moisture tension and/or plant roots themselves



So with that in mind, watching the beds adapt to  my sub surface rig is going to be interesting.  The South African research recommends that the pots should always be kept wet "by not allowing water to deplete beyond 50% capacity. This will counteract possible clogging and enhance water flow out of the clay pot".

This means I need to keep checking my water levels. It is still too early to establish a strict routine but I suspect I may need to top up the pots every 3-4 days in order to run the system at primary efficiencies.

Compared to my current watering schedule this  is less labour intensive. It also offers a ready feedback on what's happening in the soil. That's something I appreciate as it will focuse my attention more.

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Comment by Dave Riley on September 21, 2013 at 20:41


Peter Wakeling

Comment by Elaine de Saxe on September 21, 2013 at 15:45

At the time I got into Wetpots I knew the guy who developed them - being an out-of-work potter he was enthused by watching a Permaculture programme on TV showing an Indian woman using terracotta pots in her rooftop garden. They were designed to be hooked up to a micro-watering system which accounts for why they are not large enough in the neck to take hand watering. Peter um-forget his surname, we called him 'Peter Wetpots'. I did find them seemingly fragile, what their capacity is I've no idea. And how you'd know whether the pots were full or not I've no idea. I never did work that one out. Just turned on the system when I remembered to do it. One advantage wicking beds have is that the water runs out of the overflow in my system or with more complex ones, you can see how much water is in the reservoir.

The system you and others have developed using available pots is simple, cheap and by the sounds of it, effective. And being able to lift the lid and check water level is simplicity itself. What more could you ask?

Comment by Dave Riley on September 21, 2013 at 9:30

Another disadvantage with We Pots if watering by hand is that you'd be hard pressed to find the lip once the veg grew and the mulch settled.

Comment by Dave Riley on September 21, 2013 at 9:24

Are Wetpots  that thin? Then they must be more fragile and seep more. They also cost a lot more than cheaply sourced plant pots.

You do get root attachment but that's a salvage  problem only for perennial roots I'd guess. 

But hey garden pots work and the research I've read -- esp from parts of Africa and  India (and this is university level stuff) isn't precious as to shape wall thickness nor, as it turns out, size and volume. Pot aggregate mix can be a factor as all clays, even brown ones, aren't the same. 

But look at it this way I ordered my latest batch of pots online from Masters and  it cost me just over $8 for delivery. So it's a cheap entry to the method. Two pots did break and that gives you an indication of fragility. 

All up one 21 cm pot ($2.50) plus one plate ($0.50) plus a bit of gunk and an old tile chip, budgets  each station at under $4. The terracotta saucers sold for the pots are more expensive than the pots themselves!

Wetpots are  $11.50 each although they lend themselves to hose hookup as part of the system package.And the Wetpots are more enclosed with a very narrow lip which would drive you crazy if you monitored  volume and filled by hand.It would be like playing snooker with a hose. But then I can't find any volume figures for Wet Pots but I;m sure my 19cam and 21 cm pots hold moire water.

Nonetheless as I get into this more I may look at a easier filling options.

Of course any pot with a broad circumference is set ti take up mored more in the garden beds. With their lids upon their heads they look ik stepping stones. While the Olla/Wetpot shape with its pinched neck allows for for surface soil I can't see many advantages given he way the hydrology works. A inched neck and  submerged body would protect against more evaporation I'm sure and the water would be cooler.

Comment by Elaine de Saxe on September 21, 2013 at 6:31

Great report, Dave! Good that there's scientific research into this simple and effective idea. A traditional system which has come to the west. I noticed when I used the Wetpots that the plant's roots would entwine themselves tightly around the pot, making recovering the pots a bit fraught - Wetpots are quite thin, much thinner than ordinary plant pots.

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