Days to germination: 10 to 14 days
Days to harvest: Anytime during the season
Light requirements: Full sun
Water requirements: Occasional but not frequent watering
Soil: Light soil, well drained
The usual oregano variety grown in home gardens is Greek oregano. Mexican oregano isn’t really oregano at all, and it’s much more stronger flavored. Oregano is also sometimes confused with marjoram, which has a lighter but similar flavor. Marjoram is closely related to oregano but they are not the same herb.
Another type, Golden oregano, is usually grown as an ornamental plant rather than for its culinary uses. The leaves can be harvested but the flavor is quite a bit milder than regular Greek oregano.
Oregano is a perennial that will over-winter and continue to produce fresh herb for you each year. They will not tolerate extremely cold winters, so you will only be able to grow oregano outdoors between zones 5 and 10.
Its a must-have herb for any kind of Italian cooking, and it’s particularly popular in tomato sauces and pizza. Since it is typically only used as an herbal seasoning, its nutritional contribution is minimal. Still, oregano does have quite a bit of vitamin K, iron and manganese to it.
Starting from Seed
You can start your oregano plants from seed outdoors, or start indoor seedlings for transplant. Its usually easiest to just plant the seeds out into the garden (or into their pots, for container gardening). Getting a head-start with seedlings doesn’t make that much difference with herbs since they are perennials anyway. Plant your seeds in early spring, two to three weeks before your expected last frost date.
If you do start your seedlings indoors, you will still want to transplant them out into the garden after your frost date.
For spacing, you should keep your plants about 12 inches apart. At maturity, your oregano will be approximately a foot to a foot and a half tall, and 18 inches across. Vigorous harvesting will keep the plants smaller. Plant your seeds under a shallow covering of soil because they need light in order to germinate.
Oregano is a perennial, so choose your location to last for a few years. The plants don’t last forever though, and you will only get a harvest for 3 to 5 years from each plant before they get very woody. Letting one or two plants go freely to seed each year can help keep your oregano patch stay renewed each season. If your plants go naturally to seed, plan to do a little thinning the next spring as you will end up with more plants than you probably need.
To keep your oregano leaves as flavorful as possible, only water your plants when they are dry and don’t use any additional fertilizer.
You still should trim your oregano plants even if you do not need any more leaves at the moment. If you allow the plant to grow freely, it will start to get very woody and the leaves will quickly lose their pungent flavor.
If you see your oregano plants starting to blossom, pinch out the flowers right away. Once the plant bolts and goes to seed, the leaves will no longer have their wonderful flavor.
Oregano works very well in a container, and can be grown indoors or out when potted. Each plant should have a 10-inch pot to itself, with light sandy soil.
If you want to grow your oregano indoors, you’ll need a very sunny place that doesn’t get too hot. Only water your plants when the soil is very dry, and you shouldn’t need to fertilizer more than one light feeding each year.
Keep the center stem of the plant trimmed down to prevent your potted oregano from getting too tall.
Pests and Diseases
The aromatic oils in oregano are a natural pest deterrent, making it relatively pest-free. The typical herbal insect pests can be a problem for oregano too. They include aphids, thrips, mites and whiteflies. These are all very small insects and do limited harm to any plant as long as their numbers aren’t excessive.
Because you will be harvesting the leaves, don’t use any toxic pesticides on your oregano (or any herb for that matter). Pyrethrin-based sprays work best, though they need to be applied frequently. Don’t harvest any leaves right after application, and when you do pick more leaves again, wash them well.
The leafy plants can get powdery mildew, which will look like an dusty white powder on the lower leaves. It it’s not too wide-spread, just pick off the effected leaves. A fungicide spray may be necessary to keep it from spreading. Mildew likes damp environments, so when you water your oregano plants, direct the water down at the soil. Don’t pour water over the entire plant.
Harvest and Storage
Like most herbs, you just pick the leaves as you need them through the growing season. With oregano, you should wait until the plant is around 5 inches tall before starting to clip off leaves. The stems are usually a bit too woody for use, so you will have to take the leaves off individually.
You can harvest all through the summer, but the leaves will be at their peak of flavor later in July right before the plant goes to flower. If you cut out the blossoms as they appear, you will lose this “peak” of flavor, but then your plants will continue to produce for many weeks longer into the fall.
When winter hits, you may want to cover your oregano plants with mulch if you live in the colder regions of its range (like zone 5). Otherwise, they should be fine on their own until spring.
Fresh oregano will stay fresh in the refrigerator for about 5 days, if kept in a plastic bag with a damp paper towel. You can even freeze it. Dried oregano is a much stronger tasting herb than the fresh, and many people will dry it before use for this reason (not just for longer storage). You can dry it with a dehydrator, or use the traditional method of hanging bundles of the herb in a well-ventilated place until they are thoroughly dry.