Lily of the Valley Plant Profile

Fragrant but Invasive, Poisonous Landscaping Plants

Lily of the valley (Convallaria majalis). David Beaulieu

Lily of the valley is one of the landscape's toughest plants, capable of withstanding challenges that would kill more timid ground covers. It blooms in the spring and early summer—usually May. The stems are covered with tiny white, nodding bell-shaped flowers that have a sweet perfume. Green berries may succeed the blossoms, later ripening to red or orange. The plant does, however, have its drawbacks, such as being toxic to animals and humans and has the reputation for being an invasive species. It is part of the asparagus family.

Not a true lily, it is botanically called Convallaria majalis, which means "May valley." Lilies are so widely adored that the name has been loosely applied to many other plants, creating confusion for beginning gardeners.

  • Botanical NameConvallaria majalis
  • Common Name: Lily of the valley, May bells, Mary's tears
  • Plant Type: Herbaceous perennial
  • Mature Size: 4 to 8 inches high and 3 to 5 inches wide
  • Sun Exposure: Partial shade is optimal. It will also grow in full shade, but may not produce as many flowers.
  • Soil Type: Rich and moist
  • Soil pH: Slightly acidic to neutral
  • Bloom Time: Spring to early summer
  • Flower Color: White
  • Hardiness Zones: 2 through 9
  • Native Area: Northern Hemisphere of Asia and Europe

How to Grow Lily of the Valley

Native mostly to Eurasia, lily of the valley plants can be grown in planting zones 2 to 9. This puts them among the hardiest of perennials. When you buy some to plant them in your yard, they usually come as bulbous roots called "pips."

Plant them in a mostly shaded to partially shaded area (morning sun only). Grow them in well-drained, loamy soil for best results, although the plants do tolerate clay soil better than many. Amend the soil with compost.

Lily of the valley flowers prefer moist, cool conditions. The shade requirement needs to be taken more seriously the further south you get in their range. The plants will generally survive in the North from whatever rainfall you receive, but you will get better flowering if you give them water during dry periods.

Light

It grows well in part shade to full shade, as well as sun-dappled shade.

Soil

It is easily grown in moist, fertile, organically rich, well-drained soils. It tolerates a wide range of soil conditions, including dry and clay soils. Mulch to maintain soil moisture throughout the summer. Because these plants prefer rich soil, apply compost each fall.

Water

Water the lily of the valley when the top 1 to 2 inches of soil becomes dry. Avoid wetting the plants' foliage as much as possible. Water during morning hours so if foliage gets wet it has time to dry before nightfall. Do not allow the soil to become overly saturated.

Temperature and Humidity

It thrives in cool to average temperatures from 60 to 70 F. Lilies of the valley are cold-hardy to USDA Zone 2, if you plan to plant them outdoors. They naturally bloom in late spring.

Fertilizer

Fertilize lily of the valley with 10-10-10, slow-release, granular fertilizer every three months during the active growing season.

Propagating Lily of the Valley

Despite their delicate appearance, sweet-smelling lily of the valley is a tough little plant that can easily be divided and transplanted. Sprigs propagated in September and October reward you with eager regrowth the following spring and the sweetest smelling blooms in your garden in May. As an invasive plant species, it can easily double its numbers each year. The plants spread via underground stolons and rhizomes.

You will want to divide each lily of the valley plant every two to four years, or when the plant becomes crowded or outgrows its landscape area. When transplanting, create divisions that each contains a healthy rhizome and stems. Replant the divisions at the plant's previous growing depth, spacing individual divisions 24 inches apart.

This plant establishes a colony. And once it does, it is difficult to eradicate it. If you try digging it out, the smallest root left behind will produce more plants. One option, after digging out everything that you can, is to cover the affected area with a tarp for a year or so. Afterward, remove any stubborn holdovers that surface.

Toxicity of Lily of the Valley

They are poisonous plants, which is a concern if you have children or pets in the yard. Concerning the toxicity of lily of the valley plants, experts advise wearing gloves when handling them, so that any residue that you pick up is not transmitted to your food (should you forget to wash your hands before dining). All parts of the plant are considered poisonous if eaten. Symptoms of poisoning include stomach ache and blurred vision.

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; for example:

  • The rosea variety
  • Fortin's Giant
  • Flore Pleno
  • Hardwick Hall
  • Albomarginata
  • Albostriata

Their names go a long way towards describing the first two types of C. majalis. The first bears rosy-pink flowers, while the flowers on the second are larger than on the common type of lily of the valley. Flore Pleno is valued for its double flowers. The last three are kinds that have variegated leaves. Hardwick Hall has leaf margins in a chartreuse color. It is easy, at first, to confuse Albomarginata and Albostriata ("albo" means "white"). But the former has white leaf margins, while the latter has white streaks throughout the leaf. You can remember this by looking for the "marginata" in Albomarginata. 

Lovers of native plants in eastern North America may wish to substitute C. majalis with wild lily of the valley, also known as "Canada mayflower" (Maianthemum canadense), another member of the asparagus family.

Landscaping

One of the most fragrant plants, lily of the valley is the sort of ground cover that you may want in a border for a path of garden stepping stones winding its way through a remote corner of a large woodland garden.

To be enjoyed to their fullest, the plants should be massed together (the flowers being small). The plant is also used in rock gardens and moon gardens, for cut flowers and weddings, and in medicines and perfumes. Another nice thing about this ground cover is that it is deer-tolerant, rabbit-tolerant, and likes growing under trees.

One way to prevent its spread would be to use landscape edging or, better yet, the sort of barrier used to hem in running bamboo plants.

Spider mites and aphid pests may bother these plants at times. Early detection makes for an easier solution to this problem. At the first sighting of such pests, spray with organic neem oil.