Climate change and recent historic megadroughts have many in the gardening community exploring ways to tend our plants sustainably while reducing water consumption. Outdoor watering can account for up to ⅓ of average household water use, and much of it results in overwatering. That’s why we’ve been so excited recently about a very old watering technology: low-fired, unglazed terra cotta containers sometimes called Ollas. Believed to have originated thousands of years ago in Northern Africa and Asia, they were brought to the American continents in the 15th century and have been used in the centuries since with great effect, particularly in drier soil regions.
How it works
Soil moisture tension causes dry soil to draw water toward it, while the porous structure of terra cotta allows moisture seepage. Thus, when these vessels are surrounded by dry earth, water moves gradually through the terracotta walls into the surrounding soil. Plant roots gravitate toward them and draw the moisture from the moist soil. This natural, gentle, ongoing self-regulation minimizes the extremes of too much and too little water that results in waste and causes cracking in fruits like tomatoes and melons. The subterranean action means there’s less water on the surface to welcome weeds and insects, and the clay walls also provide natural filtration for the water the plants are drinking.
How do I use the Olla?
Burying the Olla in the dirt, while leaving the top 1- 2” above ground. Then fill the hydrator with water. Sandy or coarse soil is best, since it’s difficult for moisture to easily move through dense, high clay soil. Gently pack the dirt back in around the vessel removing as many air pockets as possible, as water and roots cannot cross air gaps. Cover the opening, to avoid critters getting inside and to minimize evaporation. After that, just keep an eye on the water level from time to time. When it gets too low, refill it.
Can I overwinter my Olla?
People in colder climates that freeze need to remove their Ollas before the first hard frost to prevent the risk of cracking. If you live in a more temperate place and decide to leave your Olla in the ground over the winter, remove the water and cover it in order to minimize the expansion of moisture which can put excessive strain on the clay.
How far apart should I place the Ollas?
In general, the area of effect is about the same as the dimensions of the pot, so a 1 foot wide pot will cover an area of about 1 foot around it, for 3 foot total. For a typical above ground planter pot, a single Olla is usually sufficient. In a raised bed or garden, estimate one Olla every 2-3 feet. Larger Ollas of more than 2 gallons can be spaced more widely apart.
What are the best veggies, fruits, and plants to use my Olla with?
Ollas work best with plants with fibrous tendril roots, which are capable of seeking out and massing near and around the Olla. Examples include tomatoes, pepper, squash, melons, as well as leafy greens and herbs. Use your plant hydrator to help young trees and bushes gain a foothold but be aware that larger and tougher roots can damage the pot. (If you find
yourself refilling more frequently, check for cracks.) Also, note that Ollas are not intended for seed germination, as their action is typically too deep.
Once you’ve used them for a season, you will be able to fine tune their placement for your particular growing needs. Be sure to check out the Ollas we sell in both teardrop and traditional shapes and, as always, let us know if you have questions, comments or tips, and Happy Gardening!