Artemisia annua: growing, uses & benefits

Artemisia annua, also known as sweet wormwood, is a beautifully fragrant herb with healing effects. But these are just some of the many reasons why it is worth cultivating in your garden.

Hundreds of years ago, the Chinese knew of the medicinal benefits of sweet wormwood (Artemisia annua) and used it to make a healing tea. In this article we give you advice on what to consider when growing and using Artemisia annua.

Artemisia annua: origin and properties

Sweet wormwood is also known as sweet annie or annual mugwort. It is a wild plant that originated in the temperate regions of Asia, where it is widespread. It is now common in many countries, including some parts of Europe. Artemisia annua belongs to the Asteraceae family and is just one of up to 400 species of the genus Artemisia, which also includes common wormwood (Artemisia absinthium).

The plant forms hairless brown stems that grow straight up to a height of 50 to 100 cm but can reach 200 cm in cultivation. The tender leaves of the sweet wormwood are about 3 to 5 cm long and are divided by deep incisions into numerous aromatically fragrant light green leaflets. The densely branched structure of the sweet annie can be used in a variety of ways in the garden. From August to September, many small, yellowish green flowers appear in loose panicles. The brown, rounded Artemisia annua seeds reach a diameter of just 0.6 to 0.8 mm. They spread quickly by self-seeding on suitable sites.

What is the difference between common mugwort and annual mugwort? The main difference between common mugwort (Artemisia vulgaris) and annual mugwort (Artemisia annua) is the shape of its flowers and larger leaves. In contrast to common wormwood, the flowers of sweet wormwood are arranged in delicate panicles and are yellow instead of silvery-white.

Planting Artemisia annua: location and instructions

Sweet wormwood prefers low nutrient, dry, well-drained and warm soils, and can survive in a range of light conditions from constant sunshine to partial shade.

This medicinal plant is easy to grow: simply sow direct outdoors from April onwards. Sweet wormwood seeds are light germinators, so they should not be covered with soil. Alternatively, you can also grow the seeds indoors in small pots or trays. At room temperature with sufficient humidity, the seeds germinate after two to four weeks. When they reach a height of about 5 cm, move the wormwood seedlings outside, after mid-May and any risk of frost. If the weather is cool, harden off the seedlings by gradually introducing them to the outdoors, placing them in a sheltered place for a longer period of time every day. When planting, keep a plant spacing of 60 cm to give the sweet wormwood enough space to flourish.

You can also cultivate sweet wormwood in a pot to place on your balcony or terrace. For this, put a 5 cm high drainage layer of sand, gravel or expanded clay into a large pot with a capacity of at least 5 litres to prevent waterlogging. Then add a suitable low-nutrient potting soil, such as our Plantura Organic Herb & Seedling Compost. This sustainably produced, peat-free soil stores moisture well due to its high content of organic matter, which is released to the plant roots as needed. It can be used for sowing as well as for plants with low nutrient requirements.

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Summary: Planting Artemisia annua

• Soil: Low in nutrients, dry, well-drained and warm
• Light requirements: Place in full sun to partial shade
• Sow directly outside from April and separate after a few weeks
• Alternatively: Grow indoors and transplant outdoors when they reach 5 cm from mid-May 
• Plant spacing: 60 cm
• Planting in pots: Use a drainage layer to prevent waterlogging and nutrient-poor potting soil such as our Plantura Organic Herb & Seedling Compost

Artemisia annua care

Sweet wormwood is easy to care for and only needs to be watered a little when young. After the plant has developed a good root system, you can usually stop watering. The prolific self-seeding nature of sweet wormwood can become a bit of a problem for gardeners. However, if you cut the flowering stems before the seeds form, you can limit the spread of the seeds or even prevent it altogether.

Artemisia annua is rarely affected by disease as the bitter substances and essential oils contained in its leaves keep off many pests and pathogens. Powdery mildew can occur in humid summers. The biggest problem, however, is root rot, which is caused by waterlogging and excessively moist soils.

Propagating sweet wormwood

As the name suggests, annual wormwood is an annual plant. It dies back completely in the winter and new seeds must germinate in the spring. To collect seeds, leave the plants until the seeds ripen between September and October. As soon as the seed panicles turn brown, at the latest before the first frost, harvest the entire seed stalks with garden shears. Then lay them out to dry at room temperature. To prevent the seeds from falling off when harvesting, cut early in the morning when the plants are still tough and damp with early autumn dew. After a few days, the dry seeds will drop off by themselves, then you can store them in a cool, dark and dry place.

Harvest and storage

For making tea or using it for medicinal purposes, harvest sweet wormwood shortly before or during flowering. To do this, cut off the woody branches with a sturdy pair of pruning shears as soon as the flower buds show a hint of yellow. You can then hang the plant in bundles to let it dry in the sun or at 40 °C in the oven. Then shake the dry twigs or pluck off the leaves by hand. For long-term storage, keep the leaves dry and whole, not crushed, to retain as many nutrients as possible.

Uses and benefits of Artemisia annua

The sweet annie plant has an aromatic scent of camphor or chamomile (Matricaria). It is mostly used in medicine in its dried form or as an essential oil extract. Artemisia annua tea, capsules or tinctures are often used in traditional Chinese medicine to treat fever and infections, and especially to prevent and treat malaria. The active compounds artemisinin and arteannuin are mainly responsible for the antibacterial and anti-inflammatory effect of Artemisia annua. These substances also could be used as a natural weed killer.

In various studies, sweet wormwood has been shown to have antimicrobial, anticarcinogenic, antioxidant and antiviral effects. The artemisinin has physical benefits with its high content of minerals such as zinc and selenium. Annual wormwood could therefore be used preventively for viral diseases, such as SARS-CoV-2.

Is Artemisia annua poisonous?

Similar to the invasive ragweed (Ambrosia artemisiifolia), the pollen grains of all Artemisia species can lead to allergic reactions, which is why it is best to harvest before the flowers open. Allergy sufferers should avoid cultivating the plants. When handling dried parts of the Artemisia annua plant, dust may be produced, which can also trigger allergic reactions. However, this can be avoided by spraying the branches with water.