Sweet Alyssum Flowers

How to Grow and Use This 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 due to their toughness and to the great number of blooms they produce. Because they stay short and spread sideways, they are highly versatile plants.

Taxonomy of Sweet Alyssum Flowers

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.

Plant Features, Uses in the Landscape

Technically a perennial, sweet alyssum is widely treated as if it were an annual plant in the North. But it is one of the hardier annuals, able to survive light frosts that would kill tenderer plants. Its rounded clusters of flowers are fragrant. The type with white flowers (Carpet of Snow) is the most popular. The flower has four small, blunt petals set in such a way as to give it a squarish appearance. 

These plants are indigenous to the Mediterranean region.

Sweet alyssum flowers form a striking border when used as bedding plants. Mat-forming, the plants stay short and complement taller border plants well: Planted in front of taller plants, sweet alyssum flowers will not obscure them. The plants typically stand just 4 to 6 inches high, with a spread of 6 to 9 inches. They are popular in containers: As short plants, you can install them along the rim (they will hang over 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. Use them with other white flowers in moon gardens.

The 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.

Care, Growing Needs, Outstanding Features of Sweet Alyssum

Hate to deadhead plants to encourage reblooming, because it is so time-consuming? Not to worry with sweet alyssum flowers. Just give the plants a good haircut with a pair of scissors when they start to get leggy (remove about 1/2 of the growth). Not only will this care promote further flowering, but 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.

Types With Flowers Other Than White, Meaning of the Name

Although white is the color most widely planted, types that bloom in other colors include: 

  • 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. They were regarded as antidotes to rabies.