The Many Faces of Artemisia

October/November 1993
http://www.motherearthliving.com/Plant-Profile/The-Many-Faces-of-Artemisia.aspx




With two to three hundred diverse species, the genus Artemisia offers something for every herb lover—gourmet flavor in the kitchen, outstanding ornamentals in the garden, and mainstays for the craft shop.

The group includes annuals, biennials, and perennials; many species are woody or semiwoody, and some with creeping rootstocks are ­invasive. Except for white mugwort (see below), artemisias generally have insignificant yellow or white flowers. But they are usually grown for their superb foliage, which comes in countless shapes: broadly strap-shaped, lobed, ferny, delicately lacy. Colors run the gamut from dark green to grays and silvers, even sparkling white. The green species tend to have smooth leaves, while the grayer leaves may be hairy, woolly, or felted; you may need a magnifying glass to make out the hairs.

Artemisias, members of the vast daisy family, Compositae (Asteraceae), are native to north temperate lands as well as western South America and South Africa. Many are native to the American West: The characters in Zane Grey’s Riders of the Purple Sage traveled through artemisias (Artemisia tridentata, most likely), not purple ­garden sage (Salvia officinalis ‘Purpurascens’), which is native to Mediterranean Europe. Settlers familiar with the European sage noted the resemblance in aroma to the American herb and not only gave it the same common name but sometimes also used it to flavor their food. In fact, pungent fragrance is characteristic of many artemisias, although the flowers of sweet Annie and white mugwort are sweetly scented and the leaves of the epicurean herb French tarragon smell deliciously of anise.

Most artemisias thrive in lean, well-drained soil and full sun, and most are eminently suitable for xeriscapes. Most are hardy in zones 4 through 9, ­although the humid heat of southern summers can do them in, especially if they are planted in rich soil.

Some forms tend to flop. Avoid fertilizing or planting in shade to help prevent this. Pruning will help keep plants compact, and sticks or inconspicuous cages can prop up the droopiest.

A few artemisias can be grown from seed, but most, especially French tarragon and the cultivars mentioned below, are propagated vegetatively. ­Divide plants in spring or fall. You can also root stem cuttings of new growth taken in early summer, or try rooting slightly older cuttings taken with a “heel” (a bit of the main stem) later in the summer (see “Growing Herbs from Stem Cuttings”, Herb Companion, February/March 1993). Go easy on misting, as the cuttings rot easily.

There are many ways to utilize the versatility of the artemisias. French tarragon (Artemisia dracunculus var. sativa) is an obvious choice for the kitchen garden, and wreath makers will want a stand of sweet Annie and/or Silver King. Several species are interesting historically for their role as medicinal herbs. Many are well worth growing for their ornamental value in the garden. The gray- and silver-leaved forms add texture and contrast to a plain green herbscape. They are wonderful planted next to green-foliaged mints, for example, and with bright-colored and pastel flowers. They are important elements of sunny silver or gray gardens.

The following are some particularly ornamental perennial artemisias. Some have traditional herbal uses and some don’t, but they’re all worth getting to know better.

Southernwood (A. abrotanum) 

This native of southern Europe is a sturdy shrublet that grows to 3 feet or taller. The yellowish green stems are predominantly upright, and the aromatic gray-green leaves, finely dissected into threadlike segments, remain fresh-looking throughout the summer. Pruning the plant hard in spring will help it keep its shapeliness. A line of plants can be trained into a low hedge.

Southernwood is easily propagated by layering. Pin down a lower branch (wounding the branch seems unnecessary) and cover the pinned-down spot with soil. When roots form, sever the rooted part of the branch from the mother plant, but leave the new plant where it is until the next spring. Then transplant the new plant to another ­location.

Southernwood is a favorite food of spittlebugs, tiny insects whose larvae live in globs of froth attached to the leaves and suck plant juices. Usually more unsightly than harmful, the larvae and their “spittle” can be hosed off with a forceful spray of plain water.

This herb is useful as a filler in bouquets and dried arrangements. Its pungent, sagelike aroma has prompted its use as a moth repellent. A lemon-scented cultivar just smells like southernwood to me, especially when compared to the really lemony-smelling herbs such as lemon verbena and lemon balm. A tangerine-scented cultivar is also available.

Wormwood (A. absinthium) 

This herb is native to temperate Eurasia and North Africa and grows to a height of 2 to 4 feet. Its silky, gray-green leaves are cut somewhat like those of carrot. Wormwood is well known as a potent vermi­fuge and an ingredient of absinthe ­liqueur. Surprisingly, its leaves, bitter as they are, seem to be irresistible to slugs. Locating the plant away from moist turf and mulching with sharp sand or gravel may make the plant less inviting.

‘Lambrook Silver’ is a particularly beautiful silvery cultivar that grows to about 3 feet tall. It looks great in front of a red brick wall and next to plants with reddish foliage.

‘Powis Castle’, also 3 feet tall, is an outstanding plant with feathery silver leaves, more finely cut than those of A. absinthium. It is probably a hybrid of the latter species and A. arborescens, a tender evergreen Mediterranean species. It is probably not hardy north of Zone 6 but is worth wintering indoors if you have the space.

Western Mugwort (A. ludoviciana) 

This native of the North American West grows a thicket of mostly erect stems about 3 feet tall. The silvery-leaved cultivars are prized for wreaths and dried arrangements but also look beautiful with pink flowers such as phlox. ‘Silver King’ has narrow, pale leaves on the upper part of the stem, while the lower leaves are broader and more jagged. ‘Silver Queen’ is grayer, with broader leaves than ‘Silver King’. These two are often confused or misidentified in the trade. When shopping, therefore, choose the plant that has the characteristics you want rather than a particular name. The cultivar ‘Valerie Finnis’ is less well known to herb growers. It is an upright plant, more elegant and of neater habit than the royal twosome. The upper leaves, broader than those of ‘Silver Queen’, are pale green-gray on top, white below, and the lower ones are greener and slightly woolly.

White Mugwort (A. lactiflora)

The 6-foot, erect yellow-green stems of this Chinese native bear lobed, deeply cut dark green leaves and in late summer and fall (unlike other artemisias), fragrant large panicles of creamy flowers. These make good cut flowers and are also useful in dried arrangements. White mugwort is a fine background plant for gray-leaved herbs and colorful flowers, particularly blue-flowered asters. Its own flowers are less effective paired with white flowers.

Unfortunately, deer like this herb, and it is susceptible to mildew and rust.

Roman Wormwood (A. pontica) 

This herb is native to southeastern Europe and grows 11/2 to 3 feet tall. Its delicate, ferny, triangular gray-green leaves belie its vigorous, spreading growth habit. Some gardeners would go so far as to term it invasive. There’s no need to encourage it by the application of fertilizer.

Roman wormwood is an ingredient of vermouth and other alcoholic beverages. The fine texture of its leaves makes them a good filler for fresh and dried arrangements, and they make a good base for miniature wreaths. The pressed leaves are lovely decorations for candles, note cards, and other crafts.

Silver Mound (A. schmidtiana) 

Native to Japan, silver mound is a low, silky cushion with very fine, glistening greenish white foliage. The forms available to gardeners are the cultivars ‘Nana’ and ‘Silver Mound’. There is some question whether these are actually two names for the same plant; however, ‘Nana’ is advertised as being only 4 inches tall, and many plantings of silver mound are at least a foot tall. By whichever name(s), silver mound is popular as a low edging or accent plant. Plants are attractive early in the season, but in the heat of summer, the centers gape open sloppily and ruin the bushy effect. In the deep South, the plants may not just languish but die. If you prune the plants hard at the first sign of flopping, you may stimulate a surge of new growth in fall.

Beach Wormwood (A. stellerana) 

Also listed as A. stelleriana, this herb is native to sandy beaches of northeastern Asia and eastern North America. It is a low-growing, spreading, salt-tolerant plant that looks much like the annual dusty-miller (Senecio cineraria). ‘Silver Brocade’, a recent and beautiful introduction from the University of British ­Columbia, has nonaromatic, lobed, felty white leaves and white felty stems.

Beach wormwood makes an effective ground cover and is a good foil for blue asters. Though hardy to Zone 2, it is intolerant of hot, humid summers.

(A. chamaemelifolia)

A semiwoody native of central Europe and Asia, this plant is hardy to Zone 3. It grows to 2 feet tall and has smooth, aromatic, finely cut green ­foliage.

(A. versicolor)

This herb is somewhat of a mystery: plants sold as this species may actually be A. splendens or A. canescens. What is certain is that they are low growing—less than a foot tall—and the finely cut, pale green-gray foliage is curly.

Many other artemisias, not discussed here, are also of ornamental merit. Browsing through the perennials at a well-stocked nursery may turn up a few new ones to add diversity to your herb garden. It’s likely that even more varieties will be available in the future.

Sources

The following nurseries offer an especially wide variety of artemisia plants.
• Carroll Gardens, PO Box 310, Westminster, MD 21157. Catalog $2.
• Well-Sweep Herb Farm, 317 Mt. Bethel Rd., Port Murray, NJ 07865. Catalog $2.