Lily of the Valley (Convallaria majalis) is a beloved herbaceous perennial celebrated for its delicate, bell-shaped flowers and intensely sweet fragrance that appears in the spring. This traditional plant forms a dense, low-growing groundcover, making it a popular choice for shaded garden areas where other plants often struggle. Known for its hardiness, Lily of the Valley establishes itself quickly and offers a lush carpet of foliage throughout the growing season. Proper planning is necessary to manage its growth and ensure a safe environment.
Essential Requirements for Planting
Successful growth begins by selecting a location that offers partial to full shade, as this plant thrives in conditions mimicking its native woodland habitat. While it can tolerate morning sun, intense afternoon light will scorch the leaves. Lily of the Valley is hardy in USDA zones 3 through 8 or 9, making it suitable for many temperate regions.
The ideal soil should be rich in organic matter, consistently moist, and well-draining, with a pH that is slightly acidic to neutral (6.0 to 7.0). Before planting, amend the soil with compost or aged manure to improve fertility and ensure good drainage. The plant is typically grown from “pips,” which are bare-root rhizomes, and these should be planted in the early spring or fall.
When planting, set the pips about two inches deep into the soil with the pointed growth buds facing upward. For effective groundcover, space the pips approximately four to eight inches apart. Thorough watering immediately after planting helps settle the soil around the roots and encourages initial establishment.
Ongoing Watering and Feeding Needs
Once established, Lily of the Valley requires moderate, consistent moisture. The soil should never dry out completely, but overwatering must be avoided to prevent crown rot. Applying a two-inch layer of organic mulch, such as leaf mold or shredded bark, helps retain soil moisture and regulate temperature.
Fertilization is generally minimal, especially if the initial planting site was enriched with organic matter. If the soil is poor, apply a light application of a balanced, slow-release granular fertilizer in the early spring. Alternatively, top-dressing with a layer of compost in the fall can replenish nutrients and improve soil structure.
Deadheading spent flowers is not necessary for the plant’s health, but removing withered blooms improves the appearance of the patch. The foliage should remain after flowering and naturally decay to nourish the plant for the following season. The leaves should not be removed until they have turned yellow or brown in the late summer or fall.
Controlling Aggressive Spreading
Lily of the Valley spreads vigorously by underground stems called rhizomes, which form dense colonies that suppress other garden plants. This aggressive, naturalizing tendency means containment strategies are necessary to keep the plant within designated boundaries. The rhizomes creep just below the soil surface, allowing the plant to rapidly invade adjacent areas.
Physical barriers offer the most reliable control; installing a seamless metal or stiff plastic edging around the planting area limits spread. This barrier should be sunk at least 18 inches deep into the soil to effectively block the underground runners. For smaller spaces, planting Lily of the Valley in containers provides complete control over its expansion.
Division is the primary method for managing crowded patches and propagation. When clumps become too dense, or flowering declines, the rhizomes should be dug up and separated in the late fall or early spring. It is crucial to remove all rhizome fragments when dividing, as even small pieces can sprout into new plants.
Safety and Toxicity Information
Despite its delicate appearance and pleasant scent, all parts of the Convallaria majalis plant are highly toxic if ingested. The plant contains a potent group of compounds known as cardiac glycosides, which directly affect heart function. These toxins, including convallatoxin, are present in the flowers, leaves, stems, roots, and the small red or orange berries that appear later in the season.
Ingestion can lead to symptoms in humans and pets such as nausea, vomiting, stomach pain, and general weakness. Severe poisoning can cause serious cardiac distress, including an irregular or slow heartbeat, which may lead to collapse. Even the water in a vase that has held cut stems contains these toxic substances and should be discarded safely.
When handling Lily of the Valley for planting or division, wear garden gloves to prevent potential skin irritation from contact with the plant’s sap. Due to the serious nature of the toxins, avoid planting this perennial in areas easily accessible to children or domestic pets. Immediate medical attention should be sought if any part of the plant is suspected to have been consumed.