To understand our watering needs, you must first understand where we come from. We Greek oregano plants (Origanum vulgare subsp. hirtum) are native to the arid, rocky hillsides of the Mediterranean. Our roots are evolutionarily designed to seek moisture in well-draining, often poor, gravelly soils. We thrive on neglect rather than constant attention. Our leaves are small and slightly hairy, adaptations that help minimize water loss. Therefore, our fundamental requirement is for the soil to dry out significantly between waterings. Constantly wet soil is an alien and dangerous environment for us, creating the perfect condition for the fungal pathogens that cause root rot to attack and destroy our root system.
The most reliable method to determine if we need water is not a calendar but the "finger test." You must physically check the soil moisture at the root level. Insert your finger into the soil up to the second knuckle (about 2 inches deep). If the soil at that depth feels completely dry, it is time to water us thoroughly. If you feel any moisture or coolness, wait and check again in a few days. We would much rather be slightly underwatered than overwatered. Overwatering suffocates our roots, preventing them from absorbing oxygen and nutrients, and makes them soft, brown, and mushy—the hallmark of root rot.
Our watering frequency is not static; it changes with our environment. During the hot, long days of summer when we are actively growing and perhaps even flowering, we will use water more quickly and may require watering once every 3-5 days, depending on pot size and heat. However, in the spring and fall, when temperatures are cooler and our growth slows, our water needs diminish significantly. You might only need to water us every 7-10 days or even longer. In winter, when we are dormant or growing very slowly, we need very little water indeed—sometimes only a sip every few weeks to prevent the roots from desiccating completely. Always let the soil dryness, not the season, be your primary guide.
Your watering technique is irrelevant if our home does not allow for excess water to escape. Whether we are planted in a garden bed or a container, excellent drainage is the single most important factor in preventing root rot. For container planting, you must use a pot with unobstructed drainage holes in the bottom. The potting mix is equally critical; a standard potting soil is often too moisture-retentive. You must amend it with materials that replicate our native soil, such as perlite, coarse sand, or pumice. A mix of 3 parts potting soil to 1 part perlite is an excellent start. This creates air pockets within the soil, providing oxygen to our roots and allowing water to flow through freely, never allowing it to pool around our crown and roots.
