Invasive Plant of the Month: Lily of the Valley

The Canadian Coalition for Invasive Plant Regulation (CCIPR) believes Canada should improve policies, tools and regulations to stop the spread of invasive plants.

The increasing numbers of invasive plants entering Canada each year are having serious ecological and socio-economic consequences.

Invasive non-native species spread quickly and the cost for their removal escalates over time, making management nearly impossible.

Preventing their introduction and establishment through improved legislation is the most logical and cost-effective course of action.

CCIPR is urging the Federal government to act now.

Focus on Lily of the Valley – Convallaria majalis:

Lily of the Valley is a perennial herbaceous groundcover plant native to Asia and Europe. It needs little attention after establishing, as it grows from underground rhizomes that spread horizontally with amazing speed in either full sun or full shade.

Lily of the valley has broad, green leaves, and delicate, sweet-smelling white flowers that resemble tiny bells on stalks, standing about 18 centimetres tall.

All parts of the plant are toxic and may irritate the skin. If ingested, the plant can cause abdominal pain, vomiting and irregular heartbeat.

Due to its invasive nature, Lily of the Valley forms large colonies, which out-compete native species for moisture, sunlight, nutrients, and space.

It is found in urban parks and ravines, and more remote settings of natural woodlands of southern and central Ontario.

Lily of the Valley has low wildlife value, and our native pollinators take little interest in its nectar and pollen.

If this plant brings back wonderful memories and you cannot bear to give it up, try this – take one small clump and place it in a pot, so it is contained and cannot travel.

When the flower is spent, cut it back, so it will not go to seed.

How to manage Lily of the Valley:

This can be challenging but achievable with persistence and a multi-step approach.

Manual Removal:

For small populations, dig up the plants and roots before they set seed, and remove manually. You may need to do this for several years before the seedbank in the soil is depleted and because even small pieces of rhizome can re-grow.

Alternately, cut the plants back weekly with a lawnmower. This will prevent seeds from developing and may eventually kill the plants. Do not put the plants in the compost or municipal green waste.

Smothering:

Another option for small or larger populations is to cover infested areas with tarps or cardboard to block sunlight. This can be started at any time or year, and the process can take up to two years to complete.

Check the progress each season.

Herbicide Treatment:

Difficult to reach, or large areas may be treated by herbicide. Use herbicides only as a last resort, following local regulations to minimize environmental harm.

After removal, replant the area with regionally appropriate native plants. This step is essential to prevent reinfestation and to restore ecosystem health.

Native plants will also attract pollinators and wildlife, improving biodiversity in your garden.

A good choice would be Foamflower (Tiarella cordifolia). https://www.onplants.ca/shop/tiarella-cordifolia/

Education is key to combating invasive plants. Learn to identify invasive species and choose native or non-invasive alternatives for your garden.

Focus on managing one or two invasive plants at a time and be patient.

For more information visit www.ontarioinvasiveplants.ca or www.ccipr.ca

Renee Sandelowsky and Helen Varekamp are volunteers for Canadian Coalition for Invasive Plant Regulation (CCIPR)