I admit that although I have experience growing fruits and vegetables, plants in pots often die on me. I hate to unravel the hose and drag it to the three pots on my patio every day, so I sometimes forget to do so.
I spend quite a bit of time planning automatic watering systems and the traditional drip line into a pot just doesn’t work. Unless you have a drip line valve devoted just to pots, the plants get too much water on one day but they starve for water on other days because the after-thought pot drip line generally comes from a shrub or groundcover line. We waste water on watering days as it flows out the bottom of the pot and the plants experience heat stress or dehydration on days they don’t receive water.
Because of the problem, I began to explore ways to water without a traditional watering system.
The indigenous peoples of many countries and regions, including the United States, Africa, South America and India, developed effective ways of watering plants. We have rediscovered these techniques as we seek ways to conserve water and grow foods where automatic watering systems are inconvenient. They developed ollas, deep pipe irrigation, wicking, buried clay pipes, and used swells and micro-catchments to their advantage.
I chose ollas for my planters and they work great! An olla (pronounced OY-yah) is a unglazed clay pot that is buried next to the plant. A spout of some form stays above ground so that you can fill it. Because the pot is not glazed, it will sweat water. The plant roots grow toward the pot and draw from it as needed. With this system, I only have to fill the olla in each of my large pots once a week. The olla saves so much more water than a drip line because the plants draw only what they need when they need it.
For example, if you grow tomatoes in a pot that uses an olla, you probably won’t experience cracked tomatoes. Tomatoes crack in the desert heat because they lose water in between watering times. Then when you water, they fill up with water in panic to prepare for the days/hours without it and their skins crack. With an olla, the tomato plant just takes a sip of water whenever it wants. It never stresses about when it will get its next watering. The constant access to water will make every plant healthier and since the water is directed below ground at the roots, you remove most of your weed problem when you also use ollas in your raised beds or landscapes. They aren’t just good for pots.
You can buy some beautiful ollas. I had one made by a pottery artisan in Tucson (Cutting Edge Ceramics). I love the style because it is straight and can go deeply into pots yet it doesn’t take up much room. I purchased another style online just to compare the ones I make.
I make most of my own, however, because I can make an olla for about $3 when my commercial versions averaged about $30. It takes about 15 minutes to construct and a day to cure.
You will need:
• 2 identical 6-inch unglazed terra cotta pots (for small planting pots, use two 4” terra cotta pots for the olla)
• 1 4-inch terra cotta base plate-you will use it as the lid (some people simply use a large rock)
• 1 large marble or broken pottery (any smooth non-toxic, non-porous item to plug hole in the bottom of one of the pots)
• Waterproof caulking silicone adhesive
• Caulking gun
Simply caulk the marble or your choice of an object to seal the bottom hole. I use those big shooter marbles for the 6-inch olla. I bought a large bag of marbles from a local retail store for less than $5. They will make all the ollas you want and still leave plenty for other projects or the kids.
Caulk around the top of one pot then turn the other upside down and press it onto the top of the caulked pot to adhere the two together. Run your finger lightly around the caulk to smooth it out around the edges. Don’t break the seal. If you do, you can touch it up later. Place some heavy books on top of the pots so the seal can cure overnight. Once the seal is dry, fill the olla with water to test the seal. If it still leaks, touch up the seal around the sides. Make sure that the plugged hole in the bottom is sealed properly also.
To use it in your planter, put some planting mix into the bottom of your planter (enough to raise the olla about 2 inches above your planned soil level. Soak the olla in a bucket of water for about 30 minutes to prime the clay. Empty the water out of it then place it either to the side or in the center of the planter, depending on what you are planting. Put the base plate on top of the olla to keep the soil from entering it. Fill the planter in with the soil and install your plants. Fill your olla with water and put the base plate back on. Water the planter with a hose to start the wicking process between your olla and the plants. You will only have to do this the first time.
You can test your olla water level by using a chopstick, straw –anything you can put down through the hole to test water level. The first couple of weeks, you will probably use more water as the plants draw from it. However, I have 24-inch pots, each with four plants in them, and I only have to fill the ollas weekly once they were established.
A good video on olla use was done by Kareen Erbe.