How to Grow Sweet Marjoram Indoors

Sweet marjoram is a fantastic herb for novice gardeners and home chefs alike. It thrives both indoors and outdoors, though it's not as cold hardy as other culinary herbs. Still, thanks to its easy-going nature, it has become an herb garden essential.

Native to southern Europe, sweet marjoram is slightly sweeter than its cousin, oregano, though the two herbs are often used interchangeably in food recipes. Best planted in early spring, sweet marjoram will grow slowly, with tender leaves and stems that can eventually be treated as a ground cover.

Sweet Marjoram Care

Sweet marjoram can be tough to start from seed, so it's often best to begin with small plants from the nursery. The plant enjoys well-draining soil and a normal amount of fertilizer and water and, by mid-to-late summer, your plants should be strong enough to be harvested. To do so, cut back the juicy stems and leaves of marjoram as they grow. Sweet marjoram will provide you with multiple cuttings in one season, and the plants can be divided and placed in a container to be brought inside before the first frost hits. If you would like to save the entire marjoram plant, dig it up and pot it in early autumn. As with most culinary herbs, pluck the flowers before they bloom to encourage more growth in the leaves.

Marjoram plants like to be divided and a single plant can provide you with sweet marjoram for years to come if given the necessary winter care. Like oregano, you can also hang sweet marjoram upside down in bundles to air dry. Once dry, remove the leaves from the stems and store them in a glass jar for use throughout the winter.

When it comes to cooking with your bounty, sweet marjoram is a welcome addition to both Italian and Greek cuisines. Try a sprig of marjoram in your next batch of spaghetti sauce, or pair the herb with some lamb. Keep in mind, the sweeter, more delicate taste of marjoram can get lost in some foods, so if you're using it as a substitute for oregano, use 1/3 more marjoram than you would oregano.

Light

Sweet marjoram plants love sunlight, so aim to locate your plant somewhere where it can get lots of light throughout the day. A sunny windowsill that boasts at least six to eight hours of sunlight per day would work perfectly, or you could move the plant around your home to "chase" the light and ensure it gets enough rays.

Soil

Plant your sweet marjoram in soil that is loose and well-draining. The soil's pH level isn't terribly important—it can thrive in mixtures that range from neutral to acidic. However, the most important factor is the soil's drainage. You can aid in drainage by planting your sweet marjoram in a clay or terracotta pot, which can help wick additional moisture from the soil and keep the plant from getting waterlogged.

Water

Keep your sweet marjoram plant well-watered as it's getting established and throughout its first growing season—a cadence of every seven to 10 days is usually fine, as long as the soil dries out nearly completely in between waterings. Once established, your sweet marjoram plant will be drought-tolerant, and it's ok to water it only periodically.

Temperature and Humidity

Sweet marjoram plants do not like cold temperatures, so if at all possible, you should aim to keep them between 60 degrees Fahrenheit and 70 degrees Fahrenheit at all times. Avoid temperatures below 50 degrees Fahrenheit, which includes keeping your plant near a cold breeze like an open window or an air conditioner.

Additionally, sweet marjoram does not need any added humidity—in fact, it really doesn't like it. Most homes aren't humid on their own (unless you live in an especially humid environment), but you should avoid keeping your plant in a typically humid room (like a bathroom) just in case.

Fertilizer

While fertilizing your sweet marjoram plant isn't a must, giving it regular feedings can help it to grow more lush and full. If you choose to fertilize your plant, feed it once a month with a liquid blend formulated for herbs. Alternately, you can amend the plant's soil with organic matter to up the nutrient density.

Common Pests and Diseases

Like many other houseplants, sweet marjoram has to content with a few common pests when grown indoors. Aphids, mealybugs, and spider mites can all be an issue for the herb—if you notice signs of an infestation on your plant, move it away from any other herbs as soon as possible. You can try manually removing any pests by either rubbing them off or running the plant under a firm spray of water. If that doesn't work, you can treat the plants with insecticidal soap or neem oil.

When it comes to diseases that can impact your sweet marjoram plant, most of them come about from too much humidity in the plant's environment. If the air in your home is too damp, you may find your plant has come down with powdery mildew or botrytis blight.