Full sun, part sun
Bloom Period and Seasonal Color
Blooms all summer in colors of white, lavender or pink
Mature Height x Spread
4 to 6 inches x 6 to 12 inches
attracts butterflies, attracts beneficials, deer resistant
Alyssum is a low growing annual that is known for its carpet of sweet smelling white, violet or purple colored flowers. It grows and flowers best during the coolest parts of the summer in New England, but in northern and coastal areas can be in flower all summer long. The narrow hairy leaves are inconspicuous when alyssum is in full flower. Bees, butterflies and other insects love alyssum making it a good plant in a pollinator garden. In my garden it will self-sow readily and become a permanent fixture each year. However, I still like to replant new varieties each spring for added color and to grow more vigorous plants.
Where, When and How to Plant
Alyssum grows best in well-drained, humusy soil that holds moisture well in the summer. Hot, dry spells cause alyssum to stop flowering and potentially dieback. Alyssum needs at least 4 to 6 hours of direct sun to flower well. Alyssum grows well planted directly in the garden from seed, started as seedlings indoors 8 to 10 weeks before the last frost date, or purchased as a transplant from the local garden center. Alyssum started directly in the garden from seed will bloom later than those started or purchased as transplants. Sow seeds or plant transplants in spring after all danger of frost has passed. Simply sprinkle seeds in the soil bed and lightly press them into the soil. Keep the soil evenly moist and they will germinate within one week. Plant alyssum tightly together in groups spaced only 6 inches apart to create a quicker flowering carpet effect.
Keep alyssum well-watered during hot, dry weather. It has few pests and diseases. In mid summer to stimulate more growth and flowering shear your alyssum plants by 1/3rd of their height. Fertilize afterward with a balanced product and water and they will regrow for a late summer flower show. When grown in containers or small spaces with little soil, fertilize monthly to keep them growing strong.
Regional Advice and Care
Alyssum will self-sow readily in our climate. However, the seedlings tend to have poorer quality flowers so it’s best to remove them and start again with fresh seed or transplants each year.
Companion Planting and Design
Sweet alyssum grows best where it can be showcased. Plant or sow seeds in front of flower borders, in containers with other taller growing annuals, such as salvia and profusion zinnias, and in walls or rock gardens among other low growing perennials and wildflowers, such as columbine.
Newer varieties of alyssum have sterile flowers so they don’t self-sow readily. ‘Easter Bonnet Mix’ has flowers with white, purple, and pink colors on plants that hold their mounded shape well in summer, ‘Aphrodite Mix’ has unusual apricot, salmon, and red flowers. ‘Clear Crystals Mix’ has more traditional white and pink flowers that are larger and more clearer colored.
Excerpted from my book, New England Getting Started Garden Guide.