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.
- Foliage: Oregano leaves are oval, dark green and in opposite pairs. Some varieties have fuzzy leaves, others not.
- Flowers: The flowers stalks are spiky and may be white, pink or purple.
Oregano starts out as a ground hugging rosette of leaves, but it can easily grow to about 2 ft. tall.
USDA Hardiness Zones:
Oregano heracleoticum, 'Greek Oregano', is hardy in Zones 5-9.
Bloom Period/Days to Harvest:
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.
- 'Greek Oregano', the variety usually used in Mediterranean cooking, is O. heracleoticum This is the type we associate with oregano flavor. You may also see Oregano onites listed as Greek oregano.
- O. 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.
Starting Plants: 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.
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.
Planting: 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.
Maintenance: 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.
Problems: Few pests bother oregano. Keep an eye out for spider mites and aphids.
Harvesting: 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.
Uses: It’s the leaves that are used for flavoring foods, although the flowers are edible too. They retain their flavor better in hot dishes if added toward the end of cooking. Heating too long results in bitterness. Dried oregano has a stronger taste than fresh.
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.