Lily of the Valley Plant Profile

Use Caution With this Toxic, Aggressive Plant

Lily of the valley (Convallaria majalis)
David Beaulieu

Lily of the valley (Convallaria majalis) is not a true lily; it's actually part of the asparagus family, though the foliage is reminiscent of some lilies. C. majalis typically has medium green leaves that arch from center clumps, and it sports petite, fragrant white flowers that bloom in the spring, usually April. But don't let the delicate appearance of its flowers fool you. This is a hardy ground cover that grows and spreads quickly.

Lily of the valley is a very vigorous grower, especially in cool, moist conditions. It spreads via rhizomatous roots, and while this can be an advantage where you want to quickly fill in an area, it also can crowd out nearby plants—especially other low-growing plants. If it escapes into the wild, its dense clumps can draw nutrients and water away from native plants and upset the balance of the local flora. Consequently, it has been labeled as an invasive species in parts of North America, and many gardening experts don’t recommend using it in your home garden.

It suitable regions, lily of the valley is often seen in rock gardens, and it's commonly used for cut flowers. Gardeners often use it under trees where other plants won't grow due to the shade. If you're using it in your garden, it's best to plant seedlings in the early spring. But you must be careful with this plant, as all parts of it are toxic to humans and animals when ingested.

Botanical Name Convallaria majalis
Common Names Lily of the valley, May bells, Mary's tears
Plant Type Herbaceous perennial
Mature Size 4 to 12 inches high and 3 to 5 inches wide
Sun Exposure Part shade to full shade
Soil Type Rich, well-drained soil
Soil pH 5.0 to 7.0 (acidic to neutral)
Bloom Time Spring to early summer
Flower Color White
Hardiness Zones 3 to 8
Native Area Europe; but has naturalized everywhere

How to Grow Lily of the Valley

Lily of the valley will grow vigorously in almost any spot with shade or part shade conditions. Dappled shade is an ideal environment. This plant tolerates most types of soil, but it positively thrives in moist, well-drained soil. Care should be taken when planting lily of the valley, as it will quickly colonize and take over an area. It is a long-lived plant that needs little attention, but if flowering decreases over time, lifting and dividing the plants can rejuvenate them.

There are few serious pests and diseases with lily of the valley, as befits a plant with a reputation for spreading aggressively.

Light

Plant lily of the valley in partial (morning sun only) to full shade. If you live in a warmer part of its growing zone, full shade is ideal.

Soil

Lily of the valley prefers moist, organically rich soil with good drainage. But it can grow in a range of soil types, including clay soil. It likes an acidic to neutral soil pH but can tolerate slightly alkaline soil, too.

Water

Lily of the valley likes consistently moist soil; 1 inch of water weekly, either through rainfall or irrigation, is generally sufficient. More watering may be required during hot spells.

Temperature and Humidity

This plant prefers cool, moist conditions. It will not do well in dry, hot climates. Even in mild climates, it may die back during the hottest summer months. This does not kill the plant; it generally returns the next spring.

Fertilizer

This is an aggressive spreader without any feeding whatsoever. Do not fertilize this plant unless the soil is very low in nutrients.

Toxicity of Lily of the Valley

The toxins in lily of the valley can make a person or an animal gravely ill, occasionally resulting in death. Containing at least 38 different cardenolides, lily of the valley can cause serious heart issues, among other symptoms. The toxins are most concentrated in the roots, but it is the attractive red-orange berries, which are alluring to children, that are most often ingested. Children and pets tend to experience the most severe symptoms; wild animals generally avoid the plants.

Symptoms are first identified by drooling, vomiting, diarrhea, and stomach cramps, but seizures, cardiac arrhythmia, and even heart arrest are possible. Symptoms generally occur within 24 hours of ingesting the plant. If you suspect lily of the valley poisoning, seek medical treatment immediately. Induced vomiting and IV fluids are a common treatment to flush the toxins out of the patient’s body. Some patients also might need oxygen and other supportive care.

Fortunately, if you need to work with this plant in your garden, you don’t have to worry about experiencing symptoms from handling it, as it requires ingestion to be poisonous. Just make sure to wash your hands well before handling any food.

Propagating Lily of the Valley

There is rarely a need to propagate lily of the valley, since the plants spread so readily by rhizomatous roots. If you do want to share plants, it is an easy matter to dig up a clump, break it into pieces, then replant them.

If you’re growing lily of the valley from seed, the plants typically bear flowers during their second year of growth.

Varieties of Lily of the Valley

In addition to the typical lily of the valley flowers found in gardens, you may come across some less common types.

  • C. majalis 'Rosea' bears rosy pink flowers.
  • C. majalis 'Fortin's Giant' has larger flowers than the typical lily of the valley.
  • C. majalis 'Flore Pleno' is valued for its double flowers.
  • C. majalis 'Hardwick Hall' has a yellow outline to its leaves.
  • C. majalis 'Albostriata' has white streaks throughout the leaves.

Alternate Ground Cover Plants

If you want a dense ground cover and like the look of lily of the valley, but don't like its aggressive nature, there are several plants you might consider as alternatives:

  • Solomon's seal (Polygonatum biflorum): This plant is also a member of the Asparagus family. It grows slightly taller than lily of the valley, and also does similarly well in shady conditions. It is much better behaved that lily of the valley, rarely invading where it is not wanted.
  • Summer Snowflake (Leucojum aestivum): Growing 12 to 18 inches tall, summer snowflakes has similar white flowers to lily of the valley and does well in shady conditions. While it is much tamer than lily of the valley, this plant can be invasive in some regions.
  • Siberian bugloss (Brunnera macrophylla): This is a beautiful plant with heart-shaped leaves and blue flowers, also well suited for shady conditions. Plants grow to 18 inches tall.

How to Eradicate Lily of the Valley

When the growing conditions are right, this plant will spread and establish a dense colony that crowds out other plants. It can easily escape into the wild or into a neighbor's property. If you grow weary of its growing habit, lily of the valley can be difficult to eradicate.

To limit its spread in your garden, you can use buried edging to set boundaries. Cutting the flowers off before they go to seed will also minimize the germination of new plants. 

The process for removing lily of the valley completely isn’t that difficult, but it can be time-consuming. Aim to dig up the entire plant, including all of its roots. Moistening the soil first will make it easier to slide out the roots. Even the smallest piece of root left behind can grow a new plant, so take your time to dig through the soil and remove everything you see. 

To prevent new plants from growing from any roots you missed, you can cover the site with a tarp or cardboard for at least an entire growing season. This will smother any root pieces that try to sprout.