Growing Sweet Alyssum Flowers

Use and Care Tips for the Popular White Annual

Sweet alyssum plant in bloom.
David Beaulieu

Sweet alyssum flowers are among the most popular plants sold at garden centers in North America. Their popularity is largely due to their toughness and to the great number of blooms they produce. Because they stay short and spread sideways, Alyssum are highly versatile plants.

Plant Taxonomy

Plant taxonomy classifies sweet alyssum flowers as Lobularia maritima. Do not confuse them with yellow alyssum (Aurinia saxatilis), which is a hardy perennial flowering ground cover. There is also a separate genus of plants named Alyssum, which, along with Lobularia and Aurinia, belongs to the Brassicaceae (cabbage) family. Sweet alyssum is indigenous to the Mediterranean region.

Sweet Alyssum Features

Technically a perennial, sweet alyssum is widely treated as if it were an annual plant in cold-winter climates. But it is one of the hardier annuals, capable of surviving light frosts that would kill more tender plants. Its rounded clusters of flowers are fragrant. The type with white flowers (Carpet of Snow) is the most popular Alyssum. The flower has four small, blunt petals arranged in a squarish shape. 

Landscaping Uses for Sweet Alyssum

Sweet alyssum flowers form a striking border when used as bedding plants. Because they are mat-forming and stay short, Alyssum work well as a complement to taller border plants; they can be planted in front of taller plants without obscuring them. The plants typically stand just 4 to 6 inches high, with a spread of 6 to 9 inches. They are popular in containers and can be installed along the rim, overhanging the edge slightly. Their short stature also makes them useful as temporary rock garden plants or ground covers.

White sweet alyssum flowers are used with red salvia and blue ageratum in the U.S. in patriotic landscaping themes for July 4th plantings and for decorating cemetery monuments on Memorial Day. They also work will with other white flowers in moon gardens.

Alyssum plants are most effective when massed together. The narrow leaves will hardly show at all during bloom time if the plants are packed together tightly enough. The effect is a sea of floral color.

Even for gardeners who generally have no use for annuals, sweet alyssum can be a useful plant in the landscape. One way for the perennial gardener to exploit the admirable qualities of sweet alyssum (while still treating it as an annual) is to use it as a filler. For instance, if you have a gap in your perennial beds, you could plug that gap with sweet alyssum, in lieu of having to stare at an empty expanse of mulch. The flowers also attract butterflies, as well as ladybugs.

Caring for Sweet Alyssum

If you hate to deadhead plants (to encourage reblooming) because it is so time-consuming, sweet alyssum offers an easy alternative. Just give the plants a good haircut with a pair of scissors when they start to get leggy, removing about 1/2 of the growth. Not only will this care promote further flowering, it will also keep the plants more compact. Sweet alyssum sometimes re-seeds. Grow the plants in full sun to partial sun and in a loamy, well-drained soil.

Sweet alyssum flowers boast a long blooming period, which is one reason why they are so often included in classic summer beds. The flowers are rugged, unlike those on petunias, for example. Petunias look so terrible after a strong rain that you have to clean up the plants by removing the ruined blooms. Even after a few of their flowers have died, sweet alyssum plants still look good: Their individual flowers are so small that you really do not notice a dead one here or there. This latter feature makes them relatively low-maintenance, as there is no compelling aesthetic reason to clean them after a rainstorm.

Different Types and Naming

Although white is the most common color of sweet alyssum, there are types that bloom in other colors, including: 

  • Royal Carpet (violet-purple)
  • Bicolor Pink Stream (pink-purple)
  • Easter Bonnet Deep Pink (pink)
  • Purple Shades (purple)
  • Wonderland Deep Rose (rose)

The "sweet" in "sweet alyssum" derives from the flowers' pleasant fragrance (as with sweet autumn clematis). The name, "alyssum," derives from the Greek prefix a- (which negates what follows it) and lyssa, "rage." But our ancestors had a particular "rage" in mind when naming alyssum: rabies. The alyssums (especially the yellow alyssum) were used in folk medicine as antidotes to rabies.