Oregano Plant Information

Identification

• Oregano plants are native to Europe. These herbs grow between 1 and 1.5 feet tall with an approximately equal spread, and an upright or mounding form depending upon the cultivar. Their leaves are small, hairy, dark-green, oval- or heart-shaped, and have a pungent fragrance. Oregano plants yield pink, lavender or white flowers on flowering spikes during much of the growing season.

Similar Species and Cultivars

• Origanum libanoticum or marjoram is a type of ornamental oregano that grows between 10 and 15 inches tall with an approximate 18-inch spread. The leaves are fragrant, but are not as flavorful as those of culinary oregano. This plant yields ornamental pink flowers and makes an attractive addition to rock gardens or hanging baskets. Origanum vulgare "Aureum" is an ornamental cultivar of culinary oregano. Its golden leaves add visual interest to rock gardens or borders and are also useful in dishes, according to the Missouri Botanical Garden. Origanum vulgare spp. "Hirtum," which is also called winter sweet marjoram or Greek oregano, has highly pungent, aromatic foliage and is primarily cultivated as a culinary herb.

Growing Oregano

• Origanum vulgare and many of its cultivars are hardy in United States Department of Agriculture Hardiness Zones 4 through 8. Most varieties grow well in full sunlight and can adapt to a variety of well-drained soil types and moisture levels; the "Aureum" cultivar, however, scorches easily and its leaves benefit from partial shade. Some types of oregano propagate by crown division, seeds or cuttings, while others spread through underground stems called rhizomes.

Problems and Pests

• Several types of soil-based fungi cause oregano root rot infections. The symptoms include decayed brown roots, yellowed leaves and wilt. This condition is most common in oregano plants that grow in poorly-drained or constantly wet soil. Aphids and spider mites drain sap from the foliage. Aphids are small pear-shaped insects that vary in color from green to black depending on the species, while spider mites are greenish-yellow and are too small to see clearly without magnification. Both species discolor the leaves; aphids leave a sticky liquid called honeydew on oregano plants, while spider mites spin unsightly webs on the foliage.