DIY Irrigation Pots - a Modern Take on an Ancient Technique





Introduction: DIY Irrigation Pots - a Modern Take on an Ancient Technique

About: I like blogging about urban growing and vegan food -

Ollahs (pronounced 'oy-yahs') are traditional unglazed pots, which are sunk into the soil around the base of plants. The idea is simple, you fill the ollahs with water, which gradually seeps out through the porous container directly to the roots of the plant you want to water. It is an excellent technique because -

  • It reduces surface evaporation
  • It keeps plants constantly watered
  • It cuts down the time it takes to water your garden or allotment
  • It saves water

Here's a wikipedia page explaining them -

But ollahs can be expensive to buy, and if you can't find anywhere that stocks them then you'll have to commission a potter to make some for you. Or you could just follow this easy Instructable and make one for under $5.

Step 1: What You'll Need...

To make an ollah you will need some simple materials. These are as follows -

  • Two ceramic unglazed pots.These need to be the same size, and it is essential that they are unglazed. The ones I am using here are 13cm diameter pots, and cost me under $1 at the garden centre.
  • A small ceramic saucer. This needs to be able to sit into the bottom of the pots you've selected. In order to do this I bought the smallest available. It isn't essential that it is unglazed.
  • Some glue.I'm using UHU Max Repair Extreme, because it is waterproof, flexible and suitable for unglazed terracotta.

Step 2: Seal the Hole in One Pot

The first thing you have to do for this Instructable is to seal the hole at the bottom of one of the pots. The reason that you do this is simple; if not, all the water is going to run out too quickly and the ollah becomes useless.

Put glue around the bottom of the saucer, and be very generous with the amount you put on. Invert it, and then place it in the bottom of the pot.

Step 3: Put the Two Pots Together

Once a hole is sealed at the bottom of one pot, spread glue around the top edge of that pot. Again, be generous with the amount you use - it doesn't have to look nice, it has to be watertight.

Now invert the second pot so that the top edges of both come together. Spread additional glue around the join to reinforce it.

Step 4: Let the Glue Dry

Now is time to congratulate yourself on a job almost done. Put a couple of heavy books on the pots, and leave to dry. In the meantime, have a cup of tea, read a book, learn how to play the ukulele or do something else entirely.

Step 5: Dig a Hole

Once the pots are glued together, and the glue is dry, dig a hole in the ground or the pot that you wish to water. I am planting my ollah into a 80l pot which contains an apple tree.

I live on the 8th floor, with a roof terrace that faces due south. Sometimes the pot dries out completely between me watering it in the morning and evening (it's 35degrees celsius in the summer here). The fluctuation between wet and dry puts stress on the tree and that's one of the reasons we've had few apples from it this year. With constant watering from the ollah, the apple tree will hopefully have a happy summer.

In order to sink the ollah you want to dig your hole almost as deep as the pots are tall. Sink the ollah into the hole, and leave about 3cm or 1inch above the soil line. I've also added bark chips to the top of the soil, because it makes the pots look a bit neater.

Step 6: Fill It Up!

Now all that is left to do is fill up the pot. My ollah holds about 1.5l of water, which means that in the height of summer I will most likely have to fill it up every day. However in the spring and autumn it will be good to be left a week between filling it up.

Step 7: Things to Remember...

Finally, there are a few things you want to remember if you are planning on using ollahs to water your plants...

  • Don't let them dry out completely. This can be bad for your plants because it leaves them without water, and because the ollahs can build up salt and residue from the water you use. As a rule of thumb try to keep some water in them at all times.
  • Remove them before the winter if you get ground frost. If your ground freezes then the pot will crack and be useless next year.
  • If you are making pots smaller than this one, its a good idea to put a stone over the opening at the top which will help with surface evaporation.

Thanks for reading this Instructable and let me know how your garden gets on when using them. You can follow my garden adventures at

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    65 Discussions




    ; D

    I use a plastic drinks bottle, size depending on size of pot, with a tiny hole at the bottom, and bury it as I pot the plant. The problem is to make the hole small enough for the water to drip-seep out, not gush! I did think of using wicking material to lead the water all around the plant, but not got round to that yet. The screw lid stops the water evaporating from the top

    4 replies

    That is a good idea, but do you find that the roots all concentrate around the one hole?

    I just upend the full bottle and let it leach out into the soil

    I also water from the top, but with bigger plants in bigger pots, or even in the ground, I wanted to make sure that the roots got plenty too

    I haven't noticed any clustering, not that I thought to look for any but I'm sure I would have noticed if there'd been any. Maybe because the hole, though as small as I could make it, was still too big, the water spread right across the pot, rather than seeping in one place.

    I do like the idea of using pots as in this Instructable, but I try to take up as little space as possible - even with plastic bottles, I found I was having to use a pot larger than the plant size warranted, to get the bottle in without crowding the plant.

    Simplest one I've tried so far is a length of plastic tubing buried when potting, a couple of inches above the surface so water can be tipped in.

    Great idea.

    My only concern is related to using it in tropical countries, where mosquitos are vectors for dangerous diseases. They like laying eggs in clear water under dark places.

    But I think it's just a matter of keeping a cork closing the pot hole.

    3 replies

    Or you could tape/glue a piece of window screen on it to cover the hole..

    Yeah, I'm in Switzerland so I don't really need to worry about these things, but a plate, cork or stone would all keep the critters out.

    Very nice. Im a fan of diy sub irrigation which might be a slightly better method. Or might not be! Yiu can find my description here:

    2 replies

    That's a great idea, thanks for sharing.

    Pleasure. Not my idea originally but one worth sharing.

    Tremendous. A nursery near the home markets terra cotta waterers with a similar effect, the reservoir being an inverted 2 liter PETE beverage bottle. I've several potted citrus plants which would benefit from continuous watering, but NOT at the $19 each for the small clay fixture. Three unglazed pots + drainage tray + sealer adhesive; now, I can buy that. Thank you, and my citrus plants thank you, too.

    1 reply

    $19 each!! That's exactly why I thought this up... that's a crazy amount of money.

    If you are making a few though, have a chat with the nursery. Mine was happy to offer me a bulk deal because I basically bought so many at once. I made a load for my mum and they came in under $3 each!

    Use silicon sealant, it will work just as well as it has all the properties you need - flexible, waterproof and sticks to unglazed pots!

    I would fill the completed ollahs with water and measure the time it takes to empty. This will help you to maintain a healthy amount of water in the planting. Over watering is almost as bad for plants as under watering. Adding Mulch to the pot or any planting is a very good idea. The practice helps to reduce evaporation and adds nutrients to the soil as well. Mixing your fertilizer in the water makes that process easier also.