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I occasionally post comments on  Terracotta Pot Irrigation as I've been exploring and experimenting with the method for some time.

It's a bit of a passion.


On my very sandy soil they've proven the only approach that works while saving water such that I'm more or less irrigating from my one 3,000 litre tank and only supplementing occasionally.

 My key lessons are:

  1. Pot size: at least 20 cm in diameter
  2. Routine top up: every 3-4 days usually despite the weather conditions.(My pots will take 4 days to empty whether it rains or not.)
  3. White, heavy light coloured stoneware plates for lids. Lighter or smaller plates will only be upended by crows. 
  4. Rather than cover the drainage holes with a wee tile and  sealant, I find it preferable to lay down a layer of grout across the bottom of each pot because by sealing the whole bottom,   the rate of irrigation is slowed even further by up to 25%. Water is  forced by gravity  to disperse through the sides alone. 
  5. Also test your 'sealed' pot to see if it does hold water without leaking and, conversely, that  the terracotta is permeable.  Even raw terracotta pots, seemingly from the same batch/same pottery may often not leach water -- I guess because of differences in clay structure and grog.To bury these is a waste of time and space. Grow plants in 'em instead.

My current focus is exploring the most effective and water efficient distance between pots given my soil type...while experimenting with planting patterns and sowing distances around each pot's perimeter.

I'm thinking that a Terracotta Pot Irrigated Garden requires a different template than the standard rectangular bed pattern. A wave pattern...


 While this research  argues that even small pots can maintain a wet front 60 cms from the pot for a period of 10 days, the factors impacting on distance  are variables such as soil type and clay mix.Since I need to refill mine at shorter intervals, 10 days of constant irrigation from one pot full of water aint an option. 

Of related interest are elements such as the diameter of the pot vs its depth...but my feeling is that a key factor is the surface areas on the sides of the pot that are responsive to the pressure of gravity. That means that only part of the 'walls' will be always wet enough to irrigate.

Consider a wet sponge and how water will always settle at the bottom of the sponge with varying degrees of wetness the deeper you go....while the driest area will be at the top.

These pots follow the same rules of Physics. 

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Thank you for this idea.  I would like to give it a go.  Watering 2 acres can be very time consuming (irrigation misses areas), so anything to cut down effort is good.  

Where do you get unsealed terracota pots? All the diy shops and nurseries around me sell the ones with hole(s) at the bottom and treated to be sealed.

Try this one Valerie:

Good info and looks fairly straightforward to make.

Best source for terracotta pots and best price is Masters Hardware stores . I got most of mine delivered in bulk. The wine coolers are OK but a good portion of those won't sweat water (and they are at least $3 each if you can find them). 

My complete DIY tips can be read HERE. As I discovered recently it may be preferable to seal your pot bottom with mortar as glues & silicone aren't dependable and can be fiddly. Mortar will be cheaper in the long run..and you always need to seal the bottom as that's the primary DIY task.

Nonetheless, even if you buy the same pots from the same place, some may not sweat. So keep that in mind. In my experience something like 1 in 20 may be like that.

I try to buy my stoneware plates at 50c each and I don't pay more than $1.

So a 21 cm pot will cost you $2.50 + plate at $1  + a slop of mortar ($8 for 20 kgm).

I did the figures here and compared to last Summer, which was a wet one, this season my water usage is down 45% despite the dry conditions. That's a rough estimate as I have a tank and supplement with town supply -- but those figures are off my water bill. My garden is better sustained, greener and still alive despite the strong winds and lack of good rain. 

You can go for a bigger (and more expensive) pot but remember you need a lid -- so 23 cm (or 25cm?) may be the diameter limit if you are using dinner plates. With a 25 cm plate, the lip would be hard to grasp and slow down your refilling routine. I find that if I use tiles they are upended by crows and  maybe other animals.Stoneware dinner plates settle into the pot's circumference -- a good fit.

Of course the broader the pot's diameter the more water it will hold and I think I measured the 21 cm pot  volume at 2.7 litres which gives you a rough irrigation rate of 700-900 ml per day (although there are a lot of variables in play). So to service/fill 30 pots, say, requires 100 litres of water. With reasonable water pressure and a hand held garden hose, a circuit of pot filling will take you around 20 minutes.

Do the sums. Compare it to your tank's capacity and your water budget. 

There is some 'settling in' time as the local soil and such adapts to the pot --so keep checking, by hand, what's happening within the expected moisture envelope. Even pull up the pot after a few months,  and see what is going on underneath and along the sides of the hole.

Terracotta pot watering needs to be compared to systems like Leaky hose which I installed and no longer use. I gave that up primarily because I was watering where I didn't want to --and I'd over water one time and run out of water the next. . Wicking may be more water saving but I suspect not by much and wicking irrigation seems like engineering to me --and fiddly.I'm not quite up to that (although they combine wicks with terracotta pots in India by using the pot's hole as an outlet for he wick). 


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