Oregano is one of the few herbs that tastes better dried than fresh.
Hardiness: Hardiness depends on the species or subspecies, though some are hardy to Zone 5. Most withstand a moderate freeze. In marginal areas, grow oregano as an annual or in containers that can overwinter indoors.
Soil preference: Culinary members of Origanum are easy-to-grow perennials that tolerate a variety of soils, as long as those soils are well drained. Like most Mediterranean-type herbs, they need only moderate water and grow best in a gravelly loam in full sun. If your soil retains too much moisture, grow oregano in raised beds or containers. Water. As easy as oregano is to grow, it has one definite dislike: too much moisture. Humidity, periods of excessive rain, or overwatering leads to root rot, which eventually kills the plant. To avoid it, amend your soil with plenty of organic matter to ensure better drainage. If too much humidity is a problem, encourage good air circulation by giving your plants plenty of room to spread.
Fertilizing: Oregano's fertilizer needs are minimal and often nonexistent, especially if you amend the soil with compost or other organic matter. Keep in mind that container-grown plants need to be watered and fertilized more often than plants grown in the ground. I usually fertilize my container herbs every 6 to 10 weeks during the growing season. Mulch. A stone mulch or light-colored gravel spread around the base of plants helps keep the soil surface dry.
You can begin harvesting oregano when the plant is about 8 inches high. The flavor is most intense just before the plant blooms. Frequent harvests will produce a bushier plant and keeps foliage succulent. In fact, it's a good idea to cut plants back to about 6 inches at least twice during the growing season, leaving ample growth in fall to sustain the plant through winter.
I've used both fresh and dried leaves in foods, and this is one herb that I usually prefer dried. Many chefs would agree. "Drying deepens the flavor and mellows it, so it's not as bitter," says Mark Carter, proprietor of the Carter House Inn and Restaurant 301 in Eureka, California. Cut oregano in the morning, after the dew has dried. Hang it in small bunches upside down, or lay it on screens in a warm, dry place. Once the oregano has dried (the leaves will be crisp), remove the leaves from the stems and store them, whole, in a glass container. To preserve the essential oils, wait until just before using them to chop or crush them.
Depending on the type of oregano, the flavor can be pretty strong, so start with a small amount—a little goes a long way. Taste as you go and add more if needed.