Sweet alyssum (Lobularia maritima)
Lobularia maritima, sweet alyssum, is an easy-to-grow annual known for dense, fragrant white flowers perfect for edging and borders.
Complete Plant Information
Overview
Lobularia maritima, commonly known as sweet alyssum, is treasured by gardeners for its incredible ease of cultivation and its dense blankets of bloom. This mat-forming plant creates low, spreading mounds covered with thousands of tiny, intensely fragrant flowers, often completely obscuring the foliage underneath. Its widespread appeal stems from its ability to provide season-long color, especially in cooler climates, without demanding high levels of maintenance.
As an herbaceous perennial often treated as an annual, sweet alyssum is ideal for softening borders, filling in rock gardens, or spilling over container edges. It thrives in average, well-drained soils, preferring full sun but appreciating a break from the harsh afternoon heat in warmer regions. The prolific flowering habit of Lobularia maritima ensures continuous visual appeal from spring until the first hard frosts.
Beyond its aesthetic qualities, the sweet fragrance emitted by Lobularia maritima makes it a functional choice for planting near walkways or patios where its scent can be easily enjoyed. Cultivars now offer colors beyond the traditional white, including shades of pink, lavender, and apricot, allowing for versatile use in various landscape designs.
Fast Facts
- Plant Family: Brassicaceae
- Plant Type: Herbaceous perennial
- Native Range: Southern Europe
- Hardiness Zones: USDA Zones 5-9
- Size at Maturity:
- Height: 0.25-0.75 ft
- Spread: 0.5-1 ft
- Bloom Time: April to June
- Bloom Description: White
- Sun Exposure: Full sun to part shade
- Water Needs: Dry to medium
- Maintenance Level: Medium
How to Grow
Planting Lobularia maritima is straightforward, as it is very easily grown from seed. Sow seed directly into the ground several weeks before your area’s last expected frost date for reliable spring color. For the earliest bloom, start seeds indoors about 5 to 6 weeks prior to transplanting. Sweet alyssum prefers average soil that is medium in moisture and well-drained; while it tolerates dryish soils, consistent moisture yields better results initially. Purchase starter plants are also widely available and should be set out just before the danger of frost has passed.
Care involves simple maintenance, particularly during the peak growing season. While it thrives in full sun, providing some light afternoon shade in very hot climates, like the St. Louis area mentioned, prevents stress. Watering needs are modest, classifying it as dry to medium, meaning deep waterings infrequently are better than constant shallow sprinkling once established. Little to no fertilization is usually required given its low-growing nature.
To keep the mounds looking fresh and encourage continuous flowering, shear the plantings back by about one half immediately after the first significant flush of bloom. This pruning encourages a strong second wave of flowers. In cooler summer climates, this bloom period can last spring to frost, but in intense summer heat, flowering may decline; cutting plants back encourages revival when cooler fall temperatures return. Seed can also be sown in August specifically for a beautiful fall display.
Landscape Uses
Sweet alyssum excels when used near the front edges of perennial borders, creating a dense, low-growing carpet of white or color that perfectly frames taller plants. Its habit makes it an indispensable edging material, cleanly defining paths or flower beds. Because it is such a prolific bloomer, Lobularia maritima is fantastic for mass planting to achieve a “snowdrift” effect across a large area.
In mixed container plantings, Lobularia maritima acts as an excellent spiller or filler element. Its mounding form contrasts beautifully with upright annuals or trailing ivies, while its fragrance adds another sensory layer to patio displays. Consider utilizing different colored cultivars of sweet alyssum to coordinate with brighter focal flowers in window boxes or hanging baskets.
This plant is also highly effective as simple groundcover in smaller spaces, particularly within rock gardens where its ability to tolerate drier soil can be utilized. Wherever you need a bright, low foreground element that offers continuous, low-effort color throughout the season, consider incorporating Lobularia maritima.
Standout Features
Flower Qualities
- Showy
- Fragrant
Noteworthy Characteristics
Lobularia maritima, commonly called sweet alyssum, is one of the easiest annuals to grow. It is a mat-forming plant that produces spreading mounds of well-branched stems clad with linear, lance-shaped, gray-green leaves (to 1” long). Dense clusters of sweetly fragrant, tiny, white 4-petaled flowers cover the foliage mounds from spring to early summer, often hiding the leaves completely. Cultivars expand the flower color choice to include shades of pink, rose, lavender, purple and apricot.
Tolerances
- Drought
- Dry Soil
Potential Problems
Gardeners generally encounter few serious insect or disease problems when growing Lobularia maritima. The primary issue reported is damping off, which affects seedlings, usually due to overly wet or poor soil conditions during germination. To prevent this, ensure good air circulation and avoid overwatering young seedlings. Proper seed starting techniques and using sterile, well-draining media are key preventative measures for healthy sweet alyssum starts.
Frequently Asked Questions
What hardiness zones is Sweet alyssum suitable for?
Lobularia maritima is reliably hardy in USDA Zones 5 through 9, though it is commonly grown as an annual outside these ranges.
How large does Sweet alyssum grow?
This plant typically reaches a height between 0.25 and 0.75 ft tall and spreads between 0.5 and 1 ft wide.
When does Sweet alyssum bloom?
Sweet alyssum begins flowering in April and continues through June, often blooming again in the fall if sheared after the first peak. The primary described bloom color is white.
What sun exposure does Sweet alyssum need?
Lobularia maritima performs best in locations receiving full sun to part shade.
Conclusion
Sweet alyssum is an invaluable, low-maintenance annual celebrated for its dense coverage and exquisite fragrance. Featuring the dense mats of Lobularia maritima ensures your garden borders and containers will have continuous, inviting color. Before planting, verify your local growing zone compatibility and plan to sow seeds just before your last frost date for the best results.
Companion Planting
When selecting companions for sweet alyssum, focus on plants that share similar needs for consistent moisture and sun exposure, particularly during establishment. Its low stature makes it an excellent living mulch beneath taller annuals like petunias or geraniums in mixed containers. Consider pairing Lobularia maritima with spring bulbs; as the bulbs fade, the sweet alyssum will fill in the empty space with vibrant, fragrant foliage. Plants like dusty miller or various low-growing herbs also make excellent neighbors that complement its texture without competing heavily for resources.
Container Growing
Growing Lobularia maritima in pots is an excellent way to maximize its fragrant impact near entrances or seating areas. Given its relatively shallow spread, it does well in medium to large containers, but soil must be kept consistently amended for good drainage, as containers can dry out quickly or become waterlogged easily. Since maintenance level is medium, occasional feeding during the long blooming season will keep the flower production high, preventing the plant from looking sparse midway through summer. Ensure that any container used offers sufficient drainage holes to prevent root issues, especially since water needs are categorized as dry to medium.
