Alyssum

( al - LISS - sum )

At-A-Glance Information

This genus of flowering perennials includes species commonly called Madworts. These flowers can take full sun to light shade and need regular water to perform well in the garden. They are native to the Mediterranean, and form mounds of green foliage. Yellow blooms in terminal clusters form in springtime. These low-growers are great for fronting borders and dotted amongst rock gardens. They can also do well in containers, window boxes, and hanging baskets.

Alyssum Species and Varietals

The genus Alyssum includes over one hundred species, and is part of the family Brassicaceae. Note that the plant commonly called Sweet Alyssum is not a member of this genus, but is actually a close relative in the genus Lobularia. Alyssum grows best in USDA hardiness zones 3-9 or Sunset growing zones 1-24. To find your zone, click here: Zone Map.

Alyssum alyssoides (Pale Madwort, Yellow Alyssum, Pale Alyssum, Small Alyssum, Small Alison)
This species is native to Eurasia and has naturalized itself in many areas of the world. It is at home in fields and sandy areas, reaching between 12 and 16 inches tall and producing yellow flowers which fade to white with age. Plants are in bloom from May through July. This species is considered invasive in disturbed soils of the western United States.

Alyssum artvinense (Artvinian Alyssum)
This species is native to northeastern Turkey where it is found on stony sloped areas and forest clearings. This species of Alyssum is considered endangered, threatened by habitat loss and degradation from dams, roads, and erosion. Individual plants reach up to between 4-6 inches tall. Green foliage has a silvery, hairy texture.

Alyssum dagestanicum (Dagestanian Alyssum)
This species is native to Russia and the Caucasus Mountains, and is endangered due to over-grazing and cropland development in its home range. Plants in this species grow to reach just 4 inches tall and 8-10 inches wide. They are excellent for small-space groundcover or edging.

Alyssum montanum (Alyssum gmelinii) (Mountain Alyssum, Mountain Gold, Creeping Basket of Gold, Mountain Madwort)
This popular ornamental species reaches up to 8 inches in height and to 1.5 feet wide, and produces clusters of fragrant yellow flowers in spring and summer. Leaves are grey-green. Varietal 'Berggold' ('Mountain Gold') is a popular cultivar.

Alyssum saxatile (Aurinia saxatilis) (Basket-of-Gold, Gold-Dust, Golden Tuft, Golden Alyssum)
This species hails from the mountains of central and southern Europe and Turkey. Plants have grey leaves and form a spreading evergreen mound 8-12 inches tall. Dense clusters of single or double yellow to apricot flowers bloom in spring and early summer. Golden Tuft will freely re-seed in the landscape, and is generally a hardy plant but will be taken out by extreme cold. Cultivars include 'Citrinum' (with pale yellow flowers, pictured), 'Compactum' (a denser form), and 'Variegata' (with cream-edged foliage).

Alyssum serpyllifolium (Alyssum djurdjurae) (Thyme-Leaved Alison, Thyme-Leaved Allysum)
Native to the western Mediterranean, this species does well in rock gardens. Flowers are yellow, and stems and leaves are green. This plant has the power to detoxify soil caused by rock weathering or industrialization. Reaches 2-4 inches tall and 10-12 inches wide.

Alyssum propinquum (Yellowtuft)
This yellow-flowered plant is native to southern Turkey and produces small green leaves along whitish stems. Individual plants reach just 3 inches tall and spread to 12 inches wide. This species is useful in rock gardens and small spaces.

Alyssum pulvinare (Alyssum thracicum)
This species is at home on rocky ledges and grassy slopes, and forms a tuft of greenery to between 2.5 and 6 inches tall. The species is native to central Greece, Macedonia, and Romania. Yellow flowers bloom in terminal inflorescences in May and June.

Alyssum wulfenianum (Alpine Allysum, Basket of Gold(
This species forms a trailing plant that reaches about 6-8 inches tall and 12 to 18 inches wide. Foliage is fleshy and somewhat succulent. Silvery leaves contrast well against profuse blooms of yellow flowers. This species is native to the Alps, and has a popular cultivar called 'Golden Spring'. This species prefers dry, rocky soil. This species is considered to have invasive potential in the western coastal regions of the United States.

Caring for Alyssum

Alyssum is easy to grow from seed in the garden, though it is more common to purchase it from nurseries as a potted young plant. These flowers love full sun; ideally, they should receive between 6 and 8 hours of sun every day. Well-draining soil is essential for Alyssum plants; they naturally grow in sandy or rocky soils that are lean in nutrients. These plants do not need to be mulched or fertilized. Water new plantings as they establish themselves in the landscape; at maturity, Madwort is considered to be drought-tolerant. Prune in springtime to remove leggy, diseased, damaged, or dead growth. Alyssum plants, although technically perennials, are used as annuals in zones cooler than USDA hardiness zones 9-11. In these cool zones, Alyssum plants do not survive winter temperatures are are replaced each spring. In warmer zones, Alyssums can last for years in the garden. Fertile species and cultivars will freely re-seed in the landscape, ensuring an impressive show of golden flowers each spring and summer.

Growing Alyssum in Containers
Alyssum are great choices for containers, and have a spilling effect when in front of upright plants. They can be installed in any size container. Ensure that soil is well-draining and there are adequate drainage holes on the bottom of the pot to allow for excess water to drain away. Water new plantings regularly. At maturity, Alyssum is drought tolerant. Prune to remove leggy, damaged, or diseased growth in early springtime. Move containers into a sheltered, frost-free location over the winter months to help them overwinter. Alternatively, they can be treated as annual color; pulled and replaced each spring.

Propagation

The best way to propagate Alyssum is by seed. To complete this process, you'll need well-draining soil and a pot or tray. Once you've gathered your materials, follow these steps:

Harvest seeds in late summer to fall, when most of the blooms have faded and seed heads have become tan to brown and brittle.
Prepare your pot or growing tray with soil and water it to ensure that good drainage is occurring, or prepare your planting bed outdoors by amending soil with new, nutrient rich soil. Seeds can be started indoors at any time of the year, but it is best to start them between the months of January and August. If you are direct-sowing your seeds in the ground, plant them between December and March. Place your seeds in the pot, tray, or on the soil outside, and cover them with more soil.
Carefully water your seeds, avoiding dislodging them.
The seeds should begin to produce sprouts in around eight to ten days. Once this occurs, thin seedlings out to be six inches apart.
Seedlings can be transplanted outdoors when soil temperature rises to above 55 degrees Fahrenheit.

Alyssum seed pods will look similar to this.

Alyssum seeds ready to be planted.

Problems and Pests

Take care when planting Alyssum in the landscape, as some species are considered invasive, especially in the western United States. Alyssum plants are relatively easy to grow and do not have many issues, though they are susceptible to a few problems from time to time, including: