Alyssum is a widely favored plant, cherished for its tiny, abundant blooms and sweet fragrance. This low-growing annual, or short-lived perennial in warmer climates, creates a carpet of color and scent in various garden settings. Its ease of cultivation and continuous flowering from spring to frost make it a popular choice for gardeners seeking minimal fuss.
Alyssum Characteristics and Varieties
Alyssum forms spreading or mounding habits, growing 3 to 10 inches tall and up to 24 inches wide, with stems covered in small, often gray-green, oval or lance-shaped leaves. The plant produces clusters of tiny, four-petaled flowers that often cover the foliage completely. Common flower colors include white, pink, purple, lavender, yellow, and apricot hues. These blossoms release a sweet, honey-like fragrance, particularly noticeable on warm days. Sweet Alyssum (Lobularia maritima) is the most widely cultivated species, known for its delicate appearance and profuse blooming.
How to Grow Alyssum
Sunlight
Alyssum thrives in full sun, requiring at least six hours of direct sunlight daily for optimal flowering. In regions with intense summer heat, providing partial afternoon shade can help prevent wilting and extend the blooming period.
Soil
Well-draining soil is important for alyssum, which prefers a moderately fertile, sandy, or loamy composition. While a soil pH between 6.0 and 7.0 is ideal, alyssum is adaptable to various soil types, including poorer or slightly acidic conditions. Incorporating organic matter, such as compost, can enhance soil structure and fertility.
Watering
Consistent moisture is beneficial for alyssum, especially when plants are becoming established. Aim to provide about an inch of water per week, increasing frequency during dry spells or very hot weather. Regular watering promotes better flowering and overall plant health, though established plants show some drought tolerance.
Planting
Planting alyssum can be done from seed or nursery starts. Seeds, which require light for germination, should be lightly pressed onto the soil surface after the last frost date. If starting indoors, sow seeds approximately 6 to 8 weeks before the last expected frost. Transplant seedlings or purchased plants into the garden once the danger of frost has passed, spacing them about 6 to 12 inches apart to allow for spreading.
Fertilization
Alyssum does not require heavy fertilization, especially when planted in good garden soil. In-ground plants may only need fertilizer if the soil is poor, while container-grown alyssum benefits from monthly feedings with a balanced, water-soluble fertilizer. Over-fertilizing can lead to excessive foliage growth at the expense of blooms.
Common Uses for Alyssum
Alyssum’s low-growing, spreading habit makes it a versatile plant for various garden applications, functioning effectively as a groundcover that forms a dense carpet of blooms to suppress weeds. Its trailing nature makes it suitable for cascading over the edges of containers, hanging baskets, and window boxes. It is also used as an edger along pathways, borders, or in rock gardens, where its billowy form adds a soft, colorful margin. The sweet, honey-like fragrance of its flowers enhances outdoor living spaces. Alyssum attracts beneficial insects, including bees, butterflies, and other pollinators, contributing to garden biodiversity.
Troubleshooting and Maintenance
Maintenance
Routine care for alyssum maintains a tidy appearance and encourages continuous flowering. Shearing back spent flowers promotes new blooms and prevents legginess. For larger plantings, a trim of about one-third to one-half of the plant’s height can rejuvenate growth and stimulate a fresh flush of flowers. This pruning can be done in mid-summer, especially if blooming slows due to heat.
Pests and Diseases
Alyssum is robust and resistant to most pests and diseases. However, issues like powdery mildew or root rot can occur in conditions of poor air circulation or consistently waterlogged soil. Ensuring adequate spacing between plants and maintaining well-draining soil helps prevent these problems. Aphids can affect plants, but alyssum attracts beneficial insects that help control such pests naturally.