There are about 300 varieties of Artemisia, which include wormwood, sweet Annie and mugwort.
Leaves of this plant are silver grey with fuzzy hairs that contrast beautifully against green foliage. This plant leaves wrap in spiral patterns around the tips. Larger leaves are found near the base which can reach about 10 inches (25 centimeters), while the top leaves are about 4 inches (10 centimeters).
Wormwood flowers late in summer or early in fall with small, tubular flowers that are yellow or white and grow in clusters. After they pollinate they form small fruits that carry the seeds of the plant. Flowers are used in floral arrangements or wreaths.
Many grow it as an ornamental plant in low water landscaping. It has an overpowering scent that may make some people dizzy, but it is great at repelling pests and insects.
How to Grow Wormwood from Seeds
Wormwood is considered an invasive species in the United States, so it is best to remove the deadheads of flowers in the summer months to prevent this plant from self-seeding. This will also improve the appearance of the plant. Simply cut the flowers at the base and discard them. Also pick up any seeds that may have spilled on the soil. You can collect seeds to plant them as needed or buy wormwood seeds. Place the flower heads in a paper bag and allow them to dry, then gently shake the seeds loose.
It is possible to start seeds inside or outside late in the winter (after any chance of frost) or late in the summer. The best temperature for germination is between 55-65 F (12-18 C).
Seeds are quite small, so they need to be placed on top of the soil and slightly covered with compost. Keep the soil lightly watered (moist) with a spray and place the uncovered seedling tray in a place with light. Seeds will take between two to four weeks to germinate.
Once your plants have more than two leaves, they will need to be separated at least 18-20 inches. This plant grows quite large, between 3-5 feet tall and 2 feet wide, so it will need space.
Growing Conditions
This perennial shrub grows best within USDA zones 4-9. It is pretty resistant and does not need much fertilizer unless the soil is heavily sand based. In that case place a layer or compost on the top or feed the roots with a diluted fertilizer after watering to avoid root burn.
Those that grow this type of Artemisia in a pot should place it in an area with partial shade. It can tolerate direct sunlight, but it grows best when it only receives light for a few hours per day. Full sun exposure can burn the leaves and make the stems wilt. This is specially important if you live in a warm area. The ideal temperature for this plant is between 70-77 F (21-25 C).
Loamy soil that is moderately rich and well drained is the ideal soil to grow this plant. Clay soil retains too much water, so it is not recommended. Mix soil with perlite or vermiculite to get the right texture. While it can grow in almost any soil pH, the ideal is between 5.5 and 7.5 which is neutral or slightly acid.
This herb is quite adaptable and is drought tolerant, so do not over-water it. Give it some water if the weather stays to hot and dry for more than a few days. An inch of water every week should be enough. Allow the top inch of soil to dry out completely between watering to prevent fungal infections of the roots and stems.
Watering is specially important during the first year of the plant. After the plant is established it can live without water for two or tree weeks during the summer. Withhold watering if your plant shows signs of illness such as discolored foliage or drooping stems. If it does not improve then it is best to transplant it somewhere with better drainage.
This herb is immune to pests and insects. However, it can suffer from diseases such as white rust, downy mildew and powdery mildew. These fungal infections are caused by high humidity and poor ventilation. So make sure to water your plants very little if you live in a humid area. Also space them out and prune them constantly. Remove and discard (in the trash not compost) infected plants.
It is good idea to divide and transplant plants every two or three years in autumn. Lift them completely out of the ground and cut the outer parts into sections with equal amounts of stems and roots. Throw away the center of the plant. Replant the divisions 1-2 feet apart in an area with good drainage.
Companion Planting for Wormwood
The practice of companion planting is based on the principle that some plants are good and bad for each other. Wormwood’s strong odor and taste works great to repel mice, slugs, snails, ants, fleas and ticks. It can also repel moths, so they won’t lay eggs in susceptible plants. Other insects won’t place their larvae in the ground since the strong smell can also wash into the soil when it rains or is irrigated.
Using this herb as a natural pest repellent should be done with a lot of care. It also inhibits growth of other plants (just like mugwort) due to its chemical compounds.
Wormwood should not be planted with anise, fennel and caraway. As well as with any other edible plants, unless it is in a container. Then it can be very useful for rosemary, sage, leeks, onions and carrots (since it repels carrot flees). The flavor of this herb is very strong and bitter and it will seep into your herbs and vegetables. It is possible to make a pesticide tea, but it should not be used on edible plants.
How to Harvest Wormwood
This plant needs pruning, so it should be cut in the spring to allow new growth after the winter. It is hardy enough to survive frost, however dead foliage must be cut back so the plant can grow again. Many cut the plant down to 2 inches before the winter to encourage a bushier plant the following year.
Pruning will encourage the plant to stay healthy. You can cut your plant in half with pruning shears during midsummer to stop it from getting leggy or falling because of its height. Plant discards should not be composted.
It is possible to harvest this herb after the second year, since the plant needs time to mature for it to be as strong and potent as necessary. The best time to harvest for essential oils is when the claws have opened and are just turning yellow. If the pods are green its too early to harvest and if the blooms are large, yellow and produce pollen it is too late.
This variety of Artemisia is very poisonous in its raw state. Plant it away from children, cats and dogs that consider it attractive. Do not eat the leaves of this plant as it is highly toxic. Use gloves when handling the herb.
Dry small bundles of branches upside down in a dark, well ventilated area between two to three weeks.
This herb is a great insect repellant when placed in a potpourri or sachet. Wormwood essential oil can be used as an insect spray or antiseptic. Wormwood has medicinal benefits so it is used as a tonic for people who have digestive disorders, liver or gallbladder problems. It is also used to heal skin problems, bruises and cuts. Consult with a herbalist or doctor before using wormwood for medicinal purposes.
Wormwood in Absinthe and Vermouth
Artemisia absinthium is the Latin name for wormwood. As its name suggests, it is one of the herbs used in making absinthe, along with anise, fennel and hyssop. All these herbs are distilled in an alcoholic base. Thujone, a component of wormwood, gives the spirit its hallucinogenic reputation. This magical ingredient was what caused absinthe to be banned for a hundred years.
Vermouth, used to make cocktails such as Martinis and Manhattans, is another spirit that uses wormwood. The base ingredient is some type of wine grape, as well as several spices such as chamomile, coriander (cliantro), juniper, hyssop, ginger, cloves, cinnamon, cardamom, citrus peel and quinine. Using wormwood in vermouth (and other drinks) in the 20th century reduced the use of the herb in the beverage. Although it is still used in artisan products and most manufacturers keep their recipes secret.