Olla (clay pot) sub-surface irrigation

Ollas (pronounced 'oy-yas') are unglazed terracotta pots buried in soil with only the neck exposed. Water slowly seeps through the porous clay walls, pulled outward by soil moisture tension (essentially osmosis). Plants draw water as needed, making overwatering nearly impossible. This ancient technique (4,000+ years old) is one of the most water-efficient methods available, as zero water is lost to surface evaporation. A single olla with a 1-gallon capacity waters a 12-18 inch radius circle of plants. A 4x8 raised bed typically needs 2-3 ollas. Refill every 2-5 days depending on temperature and plant size. Commercial ollas cost $20-50 each (brands: Growoya, Thirsty Earth, Dripping Springs Ollas). DIY option: glue two unglazed terracotta pots together at the rims with silicone sealant, plugging one drainage hole. Critical caveat: ollas must be removed before the first hard frost, as frozen water will crack the clay. Not practical for very large gardens due to refilling labor. Ideal for small beds, dry climates, water-conscious gardeners, and vacation periods. Combine with mulch for maximum moisture retention.