Some people find garden chores relaxing. And we would never knock the satisfaction of a long day tending the plants. But if you want more time to do other things, you haven't installed an automatic irrigation system yet, and you have no desire to tinker with apps and electronic devices, check out this low-tech clay pot irrigation method that gives you a way to water while doing something else.
What is Clay Pot Irrigation?
It's an ancient method of irrigation that utilizes an olla, Spanish for "clay pot." These unglazed pots were often bulb-shaped with narrow necks. The jars were buried in the ground and filled with water, then the semi-porous material slowly released the water into the surrounding soil, creating a very efficient watering system that conserves one of Earth's most precious resources.
How Does it Work?
Let's take a step back in time to grade school science class and that moment when you learned about the process of osmosis. Seems like only yesterday...
Osmosis is the movement of liquid molecules through a semi-permeable membrane. The movement goes from a location high in concentration (of water, for instance) to an area of lower concentration.
We can see this in action whenever we soak dried fruit like raisins in water. Those dried bits of fruit are very low in water. When soaked, the water wants to move into the raisins, so in a few minutes, those raisins will be moist and plump. Not as plump as the grapes they used to be, but you get the picture.
Same sort of deal with the ollas. When these porous clay pots are buried in the soil and filled with water, the water molecules inside the pot slowly move into the areas outside the pot (in the soil) where there's a low concentration of water molecules.
Now is probably a good time to thank your science teacher who friended you on Facebook. Science is cool, isn't it?
What's Wrong With Watering Normally?
Well, nothing really. You're providing the water that your plants need to thrive, which we all agree is important. But clay pot irrigation does offer some advantages over physically standing around and spraying your plants with a hose.
First, you don't need to stand around and spray your plants with a hose. As long as you keep the pots filled, gravity and osmosis do the work for you so you can spend more time tootling around and exploring the wonders of your work rather than hauling around the hose.
And second, if you just can't get out there, e.g. while you're on vacation and you couldn't find anyone as dedicated to your garden as you, these little guys will ensure your plant babies don't die of thirst while you're gone.
For those of you who like numbers, we submit to you some stats that might just make you go hmmm...
Number 4000: That's years. This method of irrigation has been around for 4,000 years! It's a technology most often attributed to the Northern Africans, but there's evidence suggesting it was also used in China around that time. Regardless of where it originated, it's still a valuable method that's still in use today.
Number 10: We're referring to the efficiency in this case. Clay pot irrigation compared to surface watering is up to 10 times more efficient. How can that be? Well, since the water is delivered directly to the root zone, your plants get quicker, more consistent access to the water they need. This is great news in terms of water conservation, not to mention financial savings. Which takes us to our next number:
Number 70: That's up to 70% less water used compared to surface irrigation. With water closer to the roots, you lose less due to evaporation. And with thoroughly moist soil, roots will continue to use only as much as they need.
Number 1: We're talking one square meter. That's the size of the area that can be watered using clay pot irrigation. That's pretty significant, especially if your garden is on the small side, or you've got a bed of tender or semi-hardy plants that don't do well when they don't get even moisture. And since we're speaking of moisture, the final important numbers are:
Numbers 3, 4, and 5: These are the number of days that the clay pot can hold moisture. Although it's best to top up the water level in each pot every 24 hours. This is just a good habit, and a good time to take a tour of the garden, checking on how things are progressing.
Are There Disadvantages to Clay Pot Watering?
That depends on whether you consider a little hard work a disadvantage. But you're a gardener, so we know you're not afraid of a little soil and toil. Each clay pot will require you to dig a deep enough hole to bury it.
Don't just start digging, though. It's wise to call 811 before you dig. In the United States, this service connects with different utility companies in your area who will come to your house and mark out spots where their lines may be buried. Each utility marks its locations using a different color paint.
It's a good idea to do this no matter what your project is if it requires you to dig around in the dirt. It's possible for a utility line to be only a few inches beneath the soil level, so even something as simple as planting annual petunias could potentially wreak havoc. Don't take leave it up to chance, especially when there's no charge to have the utility companies come out and mark locations. It's certainly less of a hassle than dealing with the consequences of a severed line.
Finally, that open jar of water is just begging to become a mosquito breeding ground. For this reason, it's best to keep the top covered not only to keep those pests under control but also to curb evaporation.
What Kind Should I Get?
Easy! You could start with a ready-made olla. These clay pots are unglazed and range in various styles and sizes. Modern ones can be decorative. The size you choose will depend on the site you plan on using it. Small ones can be placed in planters, while medium or large ones are more suitable for open ground.
Absolutely! If you want to relish the success of yet another DIY achievement, or you live in a place where irrigation pots are hard to find, by all means, get your DIY on. All you need are two clay pots of the same size and a tube of waterproof adhesive.
Step 1 - Clean and Dry
Clean or brush off the rims of both pots to ensure good adhesion. Allow them to dry before applying any adhesive.
Step 2 - Seal One Drainage Hole
Invert one of the pots and spread the adhesive so it covers the drainage hole. This will act as a plug so the water doesn't drain out of your homemade olla after you've buried it in the ground. You'll only need one opening at the top where you can fill it with water, much like a bottle or jug.
Step 3 - Connect the Pots
Line the rim of the other pot with adhesive, then carefully place the first pot with the sealed drainage hole on top of the pot lined with adhesive. Arrange them precisely so they sit firmly together.
Step 4 - Cure
Let the adhesive set for at least 24 hours, or however long the manufacturer suggests. After the waiting period, test your creation by filling it with water through the open drainage hole. You should be able to fill it without water seeping out from the seam where the two pots were glued together. If the water holds, it's time to get out there and garden!
Time to Start Digging
Placement of your olla is key. If you're working in a brand new garden bed that hasn't been planted yet, you don't have to worry about disturbing any sensitive roots. If you're attempting to bury the pots in an established bed, be wary of where you're digging, but place it in close enough proximity to benefit your plants.
Flip your pots so the open drainage hole is at the top, and the plugged hole at the bottom. Settle the olla in the hole so that once it's buried, you'll only have about 5cm of the pot exposed at the soil's surface.
After placement, fill the pot from the drainage hole and place a rock, a shard of terra cotta, or other object over the hole to act as cover to keep out the mosquitoes. It doesn't matter what you use as a cover, as long as it's something easy to remove so filling your olla isn't a chore.
Keep it Filled
This is part of regular maintenance and can easily be done as you stroll through your backyard oasis. Remove the cover and check the water level using a stick to test the depth. You could try eyeballing it, but it might be difficult to tell once the water drains below the soil's surface.
As long as there are no leaks, the olla should only need topping up every few days. If you discover the water level has fallen significantly after only a day, you may need to double-check for leaks or cracks that may have compromised its integrity.
Protect Your Olla in the Winter
This isn't so critical for gardeners who live in frost-free areas. Those who reside in the cooler climes will have to take a few steps to ensure their clay pots last longer than just one season. Three things to remember:
First, at least 14 days before the last frost in your area, ensure the olla is empty.
Second, cover the lid, kind of like how you winterize an outdoor faucet. It doesn't have to be anything fancy. A bit of straw and an overturned bucket are good enough, although, we know there are those for whom an overturned bucket in the middle of a bed is a blight on the landscape.
You can always try painting the bucket in weatherproof paint to add interest to the winter landscape. In any case, weight it down with a large rock to keep it from blowing away in winter winds.
Third, if you live in an area where heavy rains are followed by freezing temperatures, you'll likely have to dig up the olla to further protect it from the weather. Store it in a dry place like a garage or shed until the weather signals it's time for planting again.
Enjoy the Fruits of Your Labor
We encourage you to do this always, no matter what your project and regardless of whether you get fruit (or vegetables) or not. But now, with this new information under your belt, you can also add a note of thanks to our ancient forbears who were clever enough and skillful enough to have shown us how to work with efficiency and care to conserve one of nature's most precious resources.
With so many gardening gadgets on the market, low-tech clay pot irrigation is one of those projects that we hate to admit was low on our radar. But now we know better. And with so many other tasks to do in our gardens, why not make watering one less chore so we can spend more time enjoying our surroundings rather than working in them?
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