Sweet marjoram

Identification and origin

Origanum majorana belongs to the mint family, Lamiaceae, along with thyme, sage, and common oregano. It is native to Cyprus and Turkey and has naturalized across much of the Mediterranean basin, from Spain to Italy, Greece, and North Africa. The genus name is built from Greek words evoking mountains and beauty.

It is a perennial subshrub with a slightly woody base and soft shoots, forming a dense mound 12 in – 2 ft tall and as wide. Its square, hairy stems are often tinted or streaked with burgundy. The opposite, oval leaves, about 1 in long, are gray-green, downy, and highly fragrant. Their sweet, spicy flavor is milder and more delicate than that of common oregano.

In summer the plant forms small rounded spikes at the stem tips, like knots, from which tiny white or pale pink two-lipped tubular flowers emerge. These flowers provide late-season nectar for bees. There is also a yellow-variegated form, grown mostly as an ornamental.

It is often confused with common oregano and with Origanum onites, which is slightly hardier, stronger in flavor, and frequently sold as marjoram. The leaves and flowers are used fresh or dried in soups, sauces, stuffings, and meat dishes, or steeped as a tea.

Light

It needs full sun in a warm, sheltered spot. At least six hours of direct sun a day suits it. Indoors, set it in your sunniest window and turn the pot often so it grows evenly. A plant short on light becomes leggy: thin stems, small leaves, and a weaker aroma.

Watering

It prefers soil on the dry to moderately moist side, always well drained, and tolerates drought well once established. In the ground, a well-rooted plant usually needs no extra water; water only young plants during dry spells.

In containers, the mix dries quickly in hot, sunny weather: water when the surface feels dry to the touch, letting the mix dry slightly between waterings. It should never stay soggy, because roots rot in waterlogged soil.

Potting mix

In the ground, choose light, fast-draining soil, sandy or loamy, even poor or rocky, from neutral to alkaline. In containers, use a soil-based potting mix and a pot with a drainage hole. If your soil holds water, grow it in a container or raised bed instead, where drainage is better. It forms a spreading clump, so leave at least 8 in between it and its neighbors.

Marjoram is not a heavy feeder. In the ground it needs no fertilizer. A plant that has been in the same pot for more than a year benefits from a sprinkle of general-purpose granular fertilizer in late spring or early summer; indoors, a low dose of water-soluble fertilizer is enough. Too much fertilizer weakens its aroma and flavor.

Temperature

It loves warmth and handles hot summers very well, but it cannot survive frost: it overwinters outdoors only in USDA zones 9a to 10b, or in very sheltered corners with perfectly drained soil. Winter wet harms it too. Elsewhere it is grown as an annual or brought indoors before the first frost.

Indoors it is comfortable at 61–70 °F, with slightly cooler nights around 55–61 °F. Do not let it drop below 34 °F. Keep it away from heating vents, which dry the air; a tray of moist pebbles and good air circulation help it through winter. A sunroom or frost-free greenhouse works too.

Repotting

Grow it in a container if you want to keep it from one year to the next: just bring it in for fall. You can also dig up a garden plant before frost and pot it up. Move it back outside in late spring or summer, after hardening it off gradually to outdoor conditions. Seedlings are moved to individual small pots once they have several leaves.

Pruning

Pinch young plants when they reach 6–8 in to make them bushier. In late spring, trim established plants lightly to keep them compact and remove dead or straggly stems. Also cut back the flower stems once the blooms fade.

Harvesting doubles as pruning: snip shoots as needed, ideally before the flowers open, when the flavor is best. When the plant starts to bloom, cut it back close to the ground; it regrows with a fresh flush of leaves that is often more prized than the first. Air-dry the cut stems, then store the leaves in a sealed container.

Propagation

Seed is the easiest route. Soak the seeds overnight to help germination, then sow indoors in spring, six to eight weeks before the last frost, in moist seed-starting mix under a lid or clear plastic bag. They germinate well at about 68 °F. Keep seedlings warm and in bright light, and water sparingly, since they are prone to fungal diseases. Direct sowing outdoors is possible about two weeks before the last frost.

You can also take softwood cuttings in spring or summer, layer a low stem by pinning it to the soil in spring or fall, or divide a clump in spring or right after flowering.

Common problems

• Plant wilting and rotting at the base: soggy or poorly drained soil, especially in winter.
• Thin stems, small leaves with little scent: not enough light, common indoors.
• Plant declining indoors in winter: low light, dry air near heating, or too much water; it often overwinters poorly.
• Powdery orange, yellow, then black spots: mint rust, a fungal disease.
• Pale mottling on leaves: leafhoppers.
• Chewed leaves: mint moth caterpillars.
• Other pests: aphids and spider mites; indoors, fungus gnats, which can be trapped with yellow sticky cards.

The same symptom can have several causes: check light, soil moisture, temperature, and pests before acting.

Toxicity

Edible for people, marjoram is nonetheless toxic to dogs and cats: it contains substances that irritate the digestive tract, and eating it can cause vomiting and diarrhea. Keep pots out of reach of pets and contact a veterinarian if symptoms appear.