Overview and Description:
Culinary 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 Origanum vulgare can take many forms. Most have stems that can get very woody.
- Foliage: 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.
- Flowers: 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.
USDA Hardiness Zones:
Most oregano varieties 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.
Oregano can reach a height of 30 inches, but usually grows between 8-12 inches, especially if you are harvesting regularly. Plants will spread about 18 inches and will send out runners.
Bloom Period/Days to Harvest:
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 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.
Growing oregano is easy, but choosing the right variety is sometimes confusing. Plants in the genus Origanum are can be perennial ground covers, tender perennials or even small perennial sub-shrubs. There are many named oregano varieties, but the common names tend to vary by region:
- '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.
- 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 Growing Tips:
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.
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.
Few pests bother oregano. Keep an eye out for spider mites and aphids.
How to Harvesting and Use Oregano:
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.