Oregano is a popular culinary herb, prized for its pungent, slightly peppery flavor that defines many Mediterranean and Mexican dishes. Gardeners often face a common question about the plant’s usability once it begins to flower, a natural stage of its life cycle. While the flavor profile of the leaves shifts after the bloom appears, the oregano plant remains completely safe and usable in the kitchen. Understanding how the plant’s chemistry evolves is key to maximizing the harvest from a mature plant.
How Flowering Changes Oregano’s Chemistry and Flavor
The distinct, warm flavor of oregano comes from a group of aromatic compounds known as essential oils, primarily carvacrol and thymol. These compounds are produced by the plant in specialized glands on the leaves, and their concentration determines the herb’s potency. When the oregano plant begins its reproductive phase by producing flowers, it redirects its energy away from vegetative growth, which includes leaf development. This shift in physiological focus impacts the chemical composition of the leaves.
The energy diversion means that the concentration of carvacrol and thymol in the leaves often decreases. Studies suggest that a flowering plant can lose a significant percentage of its essential oil content compared to its pre-bloom state, leading to a muted flavor. In some varieties, the flavor may even become slightly bitter or less balanced due to changes in the ratio of the different aromatic compounds. Although the herb is not spoiled, its characteristic intensity is reduced.
Post-Bloom Harvesting: Timing and Technique
Even after the plant has flowered, a successful harvest is still possible by using the correct timing and technique. It is generally best to harvest in the morning after the dew has dried but before the sun’s full heat has developed. This timing ensures that the remaining aromatic oils in the leaves are at their highest concentration before the heat causes them to volatilize.
To collect the stems, use clean, sharp scissors or shears, cutting just above a leaf node, which is the point where a new set of leaves emerges from the main stem. This technique encourages the plant to branch out and produce new, softer growth with better-flavored leaves later in the season. If the stems have become woody, they should be used cautiously in cooking, as the tough material is not pleasant to chew and is better suited for flavoring liquids like stocks or broths.
Stimulating New Growth
Cutting back the plant after flowering, sometimes by as much as one-third of its height, can often stimulate a flush of new, more tender leaf growth before the end of the growing season.
Preparation and Culinary Use of Mature Oregano
The most effective way to process mature, post-flowering oregano is through drying, which helps to concentrate the remaining flavor compounds. You can dry the harvested stems by bundling them together and hanging them upside down in a warm, dark, and well-ventilated area for one to two weeks. Alternatively, a food dehydrator can be used for a quicker process.
Once the leaves are completely dry and crumbly, they should be stripped from the stems and stored whole in an airtight container away from light and heat. Keeping the leaves whole until just before use helps to protect the fragile essential oils, maintaining maximum potency. Since the flavor of mature oregano is less intense than pre-flowering material, you may need to use a slightly higher quantity in recipes to achieve the desired taste. The small, often purple or pink, oregano flowers are also edible and can be used as a mild, decorative garnish for salads or savory dishes.