Clay Pot Irrigation

Here's an 8 inch clay pot.  You can get these at the big box hardware stores for around 3 bucks.  They are unglazed.  There is no coating of paint or enamel.  What this means for folks that want to garden is these pots can be used as an inexpensive, slow and steady irrigation tool.  You may have heard the terms 'olla', 'pitcher irrigation' or 'clay pot irrigation'.  Whatever you prefer to call it, the principle function is the same.  Unglazed clay allows water to seep out of the vessel through the walls and bottom.  When mostly buried, the water is served to the root zone of the plants where it is needed most.  There is no overhead water coming down to compact the soil.  Weed seeds on the surface of the soil are not helped out.  The plant leaves remain dry.  This is especially handy for plants susceptible to downy mildew.


There is a little bit of prepwork to do.  These standard pots are designed for flowers and plants being displayed above ground.  They have a hole in the bottom to allow rapid draining so as not to drown the plant.  For our use, the hole will need to be plugged.  Wine bottle corks work well.  In this example I have used some pieces of foam insulation.

Dig a hole deep enough to fit the pot up to the bottom of the lip. I leave the top edge a couple inches above the soil because I will add a couple inches of mulch. Make the hold wide enough for the pot plus a couple inches all around so you have room to work. I'll compress the soil on the bottom of the hole to offer better support and to fill any empty spaces so the pot does not fall in deeper down the road.

Settting The Pot
Keeping the pot flat and level may take a touch of finesse. If there are roots of any size down in that hole, they can prop the pot on a tilt. A tilted pot won't hold as much water when filled. If a cover will be added, having a level surface prevents the lid from sliding off. You may need to shove your thumb into the soil to allow space for the plug.  Trial and Error is the method I employ.  Give it a wiggle, add or remove soil, cut roots.  The pot should sit flat without falling over.

With the pot in place, fill the space around the pot.  Voids needs to be filled.  The water can't leap a gap.  It will be moving through the soil via capillary action.  To improve the effect, pack the soil around the pot to a distance of 'a couple inches'.  I go to great lengths to keep the tilth of my growing beds light, but I'll bite the bullet here.  The plant roots will find their way to the water source and will break up the soil.  Every couple years I have to pull the pots out and remove the roots which have formed a thick mass all around these pots.  Makes a great addition to the compost heap.


Time to fill the pot.
I have a garden hose that will reach. I could use the hose to water the plants, but standing there for 15 minutes is a waste of my time. I can come through to fill a few pots in no time. They'll water the plants for me.
From time to time stuff will get into the pot: leaves, weeds, spiders...toads. I leave the toads alone; They eat bugs. To wash out the debris, I leave the water running. This creates a whirlpool pushing the debris up and out. The overflow will help to compact the soil in the immediate vicinity which will improve capillary flow.

Plants on the bottom, left to right: Snowball Improved Cauliflower, Purple Top White Globe Turnip, and an onion grown from the root end of an onion I ate weeks ago. You'll see that same onion in an earlier stage in the last photo of my article about Potting Up Seedlings.


The area covered by this irrigation method will reach a distance of 1.5-2 feet as measured from the center of the pot. Using that 8" pot as a reference, the area served encompasses everything in this photo. By placing pots down the center of a growing bed every 3-4 feet I can achieve excellent coverage. This is a sandy soil which allows excellent water movement. Your success will be determined by your soil type.

The water is drawn out according to the moisture level in the soil. A dry soil can empty the pot in a day. Moist soil will see several days before the pots empties. A good rain can see water move from the soil back into the pot. That's a feature you don't get from a drip line. How often you fill the pot is up to you. I like to let mine run dry once a week to prevent mosquito larvae from developing.

The clay pots are a convenient and effective means of irrigating a garden. In a location that cannot be reached with a hose, water can be hauled to the pots in containers. The pots can be quickly filled without disturbing the soil or the plants. Covering the soil with a thick layer of mulch will conserve water, which will save you a trip hauling jugs. A lid can be added. I find ceramic floor tile to be effective. It will reduce evaporation, but a greater advantage may be found by a lid keeping cats from trampling your plants while looking for a drink.