The genus of Artemisia contains about 300 species of plants. It is in the Asteraceae (daisy) family, but you will not see a lot of showy flowers with the Artemisia species. The genus includes annuals, perennials, and even woody shrubs, but those cultivated for garden use are mostly herbaceous perennials. Most artemisias are grown as foliage plants and valued for their filagree-like leaves.
Several familiar Artemsia species go by familiar common names: southernwood (A. abrotanum); wormwood, also called absinthe (A. absinthium); mugwort (A. vulgaris); sagebrush (A. tridentata); and the culinary herb called tarragon (A. dracunculus). But those used as landscape plants are often named cultivars that are known simply as "artemisia."
Artemisia is often considered an herb, either culinary or medicinal. Most of the species are heavily scented and many have a somewhat bitter taste, which makes them very unattractive to browsing animals but useful for their essential oils.
Artemisias have alternate leaves in various shapes. Very often the leaves are lobed, and they are generally covered with whitish hairs that give the leaves a silvery, grayish look. Their flowers are small (1/16 to 3/8 inches), white or yellow, and cylindrical. The flowers are often clustered in panicles, but sometimes they are single.
Artemisia is normally planted from nursery-grown plants in the spring as soon as the soil can be worked, but this sturdy plant can really be planted almost any time. It will grow quickly, achieving full size within a couple of months. Established clumps will return even quicker each spring.
Many artemisia species are considered invasive in some parts of the U.S. Check with a local expert before planting, and take care to prevent your plants from escaping into surrounding land.
|Botanical Name||Artemisia spp.|
|Common Names||Artemisia; individual species may be known as wormwood, absinthe, southernwood, mugwort, etc.|
|Plant Type||Mostly herbaceous perennials; genus also include some annuals and woody shrubs|
|Mature Size||8 inches to 5 feet tall depending on variety|
|Sun Exposure||Full sun|
|Soil Type||Any average, well-drained soil|
|Soil pH||Any soil pH|
|Bloom Time||August to September|
|Flower Color||White or yellow|
|Hardiness Zones||4–10 (USDA); varies according to species|
|Native Area||Depends on species|
|Toxicity||Oils may cause skin irritation; tarragon is toxic to dogs and cats|
Artemisias are relatively low-maintenance plants, but they do have some preferences when it comes to growing environment. They will grow best in a full sun location, although most varieties can handle part shade.
A vignette of all silvery and white plants looks striking in semi-shade, such as is achieved when you pair artemisia with lamb's ear (Stachys byzantina), Pulmonaria, and white variegated grass. Gray leaves also pair nicely with just about any pastel, especially pinks and blues, as well as with mauve-pinks, like Joe Pye Weed (Eupatorium) and Centranthus ruber.
A beautiful use for artemisias is to pair them with the spiky, deep blues and purples of salvias and irises. Or watch what they do to liven purple coneflowers (Echinacea). Small plants are great for containers, while taller and bushier varieties can be used as a summer hedge.
Artemisias grow best in full sun, but some types will tolerate some shade, provided they get up to six hours of sun.
With a few exceptions, such as Artemisia lactiflora, Artemisias need well-draining soil on the dry side. If left sitting in damp soil, they will decline and/or be short-lived.
As with most silver-leaved perennials, Artemisia plants are very drought tolerant. They will need regular water until the plants are established, but they can take care of themselves after that.
Artemisias do not like overly rich soil. Since artemisias do not like rich soil, no supplemental fertilizer should be necessary, especially if you are regularly adding organic matter to your beds.
Is Artemisa Toxic?
Official lists of poisonous garden plants generally list Atemisia as a class 4 toxin, meaning that it is capable of causing dermatitis (skin) reactions upon contact. There is also some evidence that the concentrated artemisinin oil, sometimes taken as a folk medicine remedy or as an ingredient in cancer-fighting drugs, may lead to liver damage. But such effects are not possible with accidental ingestion of garden plants.
Artemisia plants are not generally included on lists of plants toxic to animals. However, tarragon (Artemisia dracunculus) is the exception, with clearly documented toxicity for dogs and cats.
Symptoms of Poisoning
Contact with the oils in artemisia leaves can cause skin rashes, hives, and other skin reactions in people. Treatment is generally a simple matter of washing and rinsing the skin.
Tarragon consumption has been known to cause vomiting, excessive salivation, low blood pressure, coma, and in rare cases, death in dogs and cats. Given the chemical similarities between Artemisa speices, it is probably a good idea to prevent pets from eating other forms of Artemisia, even though they are not commonly known to be toxic.
- 'Canyon Gray' (Artemisia californica 'Canyon Gray'): Also known as canyon sagebrush, this variety stays under 2 feet and height but can spread as much as 10 feet, making it an excellent groundcover. It is hardy in zones 9 to 10.
- Mugwort (Artemisia vulgaris): This 2- to 4-foot tall plant has a sage/mint aroma and flowers with greenish-white blooms that appear in mid- to late summer. It can be grown in zones 5 to 10.
- 'Powis Castle' (Artemisia 'Powis Castle'): This is a hybrid variety, an upright plant growing 2 to 3 feet tall with silver-gray fern-like foliage. It can be grown in USDA zones 7 to 10.
- 'Silver King' (Artemisia ludoviciana 'Silver King'): This plant is a fast-spreading variety with bright silver-white leaves that turn reddish in fall. It grows up to 4 feet tall and is hardy in zone 4 to 9.
- 'Silver Brocade' (Artemisia stelleriana 'Silver Brocade'): This is a low-growing 6- to 8-inch tall plant that spreads about 1 foot. It has wooly white leaves and is often used in containers or planted into crevices of retaining walls.
- 'Seafoam' (Artemisia versicolor 'Seafoam'): This ground-hugging 8-inch variety has billowy silver foliage and is hardy in zones 4 to 10.
- 'Silver Mound' (Artemisia schmidtiana 'Silver Mound'): Forming 1-foot mounds of soft-textured light green foliage, this variety is hardy in zones 5 to 10.
Perennial artemisias can be cut back in the fall or spring. Shrubby varieties should be pruned in the spring. They can handle being cut back hard if you want to keep their size in check. Even non-woody artemisias can get floppy, especially after flowering. Give them a shearing mid-summer to prevent them from splitting open in the middle.
Plants can be started from seed, divisions, or cuttings, but many of the newer hybrids are sterile and the others will not grow true to seed. Thus, propagation is most often done by simple division of the root clumps, which offers the fastest, most trouble-free method.
Divide plants every two to three years, or when you start to notice the center beginning to die out. This is a simple matter of digging up the entire plant, dividing the root ball, and replanting.
Luckily, if the conditions are ideal, artemisias are quite resilient. Because of their strong scent, insects tend to avoid artemisias. But they can be prone to many fungal and rust diseases, like white rust, powdery mildew, and downy mildew. Hot, humid weather exacerbates these problems. Growing them in an open area with good airflow will help mitigate the problems.