Oregano is a signature flavor of many Italian, Mexican and Spanish dishes. Most cooks are familiar with it in its dried form, but oregano is a hardy perennial plant that is easy to grow in the home garden. A handful of plants will provide you with enough oregano to use fresh in season and to dry for use throughout the winter.
There are many varieties, but the most common variety for cooking is 'Greek' oregano.
The more pungent 'Mexican' oregano, Lippia graveolens, isn't really an oregano at all. Mexican oregano is often used in chili powders. 'Golden' oregano is very ornamental, but not as flavorful.
Plants in the genus Origanum are can be perennial ground covers, tender perennials or even small perennial subshrubs. Even common oregano, Origanum vulgare, can take many forms. Most have stems that can get very woody.
Oregano leaves are oval, dark green and in opposite pairs. Some varieties have fuzzy leaves, others not. Oregano starts out as a ground-hugging rosette of leaves, but it can easily grow to about 2 ft. tall.
The flowers stalks are spiky and may be white, pink or purple. Bees love oregano flowers and will cover the plants, taking up nectar and pollen. Some beekeepers plant oregano nearby because it adds a wonderful flavor to the honey made by the oregano-eating bees.
Most types of oregano are reliably hardy in USDA Hardiness Zones 5-10. The most popular variety for cooking, 'Greek Oregano' (Oregano heracleoticum), is hardy in Zones 5-9.
Most oregano varieties need full sun, however 'Golden Oregano' does best in partial shade; its leaves tend to scorch in full sun.
Oregano plants can reach a height of 30 inches but usually grow between 8 - 12 inches, especially if you are harvesting regularly. Plants will spread about 18 inches and will send out runners.
As with most herbs, oregano leaves taste best before the plant flowers. You can begin harvesting when plants have reached 4-5 inches in height. Cutting stems all the way back to the ground will encourage more stems from the base and a fuller plant.
The stems tend to get woody and the easiest way to strip the leaves is to hold the stem by the top, uncut end and run your finger down the stem.
In Garden Design
Although it is grown predominately as a culinary herb, oregano makes a nice edging plant and ground cover, requiring little maintenance. The smaller varieties also do well in rock and alpine gardens.
Growing oregano is easy, but choosing the right variety is sometimes confusing. There are many named oregano varieties, but the common names tend to vary by region. It helps to know the botanical name, although that is not always available. Unless you are growing it only for ornamental reasons, the best option for choosing an oregano is to taste and smell it.
- "Greek Oregano" is the variety usually used in Mediterranean cooking, is Oregano heracleoticum This is the type we associate with oregano flavor. You may also see Oregano onites listed as Greek oregano.
- Oregano vulgare is known as "Common Oregano", "Wild Marjoram" and "Pot Marjoram". Marjoram is a type of oregano with a less pungent, sweeter taste, often used in French and English cooking.
Oregano plants can be started from seeds, divisions or cuttings. Since different species of oregano will cross-pollinate, you may not get what you expect from seed you saved yourself.
Oregano seeds require some light to germinate, so cover only slightly with soil. Start seeds indoors and transplant when temperatures remain above 45 degrees F.
Oregano plants are widely available in nurseries and through specialty catalogs.
Catalogs tend to offer the widest variety of oregano plants.
Oregano is one of those 'Mediterranean' herbs that like well-drained soil, on the lean side, and full sun. Rich soil tends to dilute the pungency of the flavor. Climate, soil, and moisture can cause variation in oregano’s flavor. The genus is native to the Mediterranean area, but Oregano vulgare has naturalized in many areas, including the eastern United States.
The flowers should be pinched to keep the plants bushy and prevent them bolting to seed.
Divide plants when the centers begin to die out or the stems become too woody. You can also divide plants simply to make more plants.
Oregano may need some winter protection in Zones 5 and lower. Covering the plants with an evergreen bough, after the ground has frozen, will protect them from wind damage.
Most of the pruning oregano needs will be accomplished by harvesting, but to keep it healthy, follow the guidelines for pruning woody herbs.
Pest and Problems
Few pests bother oregano, but keep an eye out for spider mites and aphids.
Once the plant has reached 4 - 5 inches tall, you can start cutting sprigs for use. Harvesting before the plant blooms will yield the most flavorful leaves. Levels of essential oils diminish as the flowers begin to develop.
It’s the leaves that are used for flavoring foods, although the flowers are edible too. The leaves retain their flavor better in hot dishes if added toward the end of cooking. Heating too long results in bitterness. Use less dried oregano than fresh, because it has a much stronger taste when dried.
Note that there are plants outside of the Origanum genus that are sometimes referred to as oregano.
'Mexican Oregano' can mean either Lippia graveolens or Poliomintha longiflora. They are considered similar in flavor, but stronger than oregano. In Puerto Rico and Cuba, Plectranthus anboinicus can be found labeled as oregano. Thymus nummularius is often used in place of oregano, in Spain.