Invasive plant of the month

Periwinkle is an invasive plant that can be replaced with Wild Geranium.

As consumers, we assume that garden centres would never sell plants that can do harm.

Sadly, this assumption is incorrect as the sale of many high-risk invasive plants is not regulated in Ontario.

Invasive plants have been introduced from other parts of the world and are known to have detrimental impacts on human health, the environment, and the economy.

Some high-risk invasive species on the Ontario Auditor General’s ‘Do Not Plant or Sell List’ include Burning Bush, English Ivy, Amur Maple, Lily of the Valley, Periwinkle, Japanese Barberry, Pachysandra and Japanese Honeysuckle.

Next time you go to a garden centre, consider asking if the plant you are buying is invasive or not, and if it is, ask why it’s not labelled as such.

As a consumer, we all have a right to know what we are purchasing and eventually planting.

Focus on Periwinkle – Vinca minor

In the Bayfield area and beyond, Periwinkle has become a major issue, taking over large areas of natural habitat.

This plant thrives in shaded, moist conditions such as forested areas and along waterways, but can grow even in dry shade.

Its ability to reproduce through underground roots as well as any fragment of its stem, transported via water, wind or animals, makes it difficult to control and quick to dominate.

Periwinkle spreads forming dense mats that exclude other plants including trilliums and tree seedlings.

Despite its harmful impacts, Periwinkle remains one of the top six invasive species still sold in garden centres.

I advise readers to stop purchasing, sharing or trading this plant to help prevent further ecological damage.

How to Manage Periwinkle

Managing Periwinkle is challenging, but achievable with persistence and a multi-step approach.

Your control efforts should focus on preventing the spread of this invasive species. Focus on edges first, reversing the invasion front.

Manual Removal:

Removal is most effective when the soil is moist, especially in clay soils.

Work on a small section as a time.

For sprawling runners, use a rake to lift them from the ground and mow the area to help contain the spread.

Dig out plants, ensuring roots are fully removed. Place plants in black plastic bags and dispose in garbage, never in the compost or municipal green waste.

Repeat inspection and removal of Periwinkle regularly for at least a year.

Smothering:

Cut the Periwinkle down and cover smaller infestations with tarps or cardboard or a thick layer of mulch to block sunlight and water.

This can be started any time of the year, and the process can take up to two years to complete.

Herbicide Treatment:

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 essentially 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 Wild Geranium – Geranium Maculatum.

Learn More and Take Action

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 – successful eradication of invasive plants takes time and persistence.

For more information visit www.ontarioinvasiveplants.ca/resources/grow-me-instead

Renee Sandelowsky and Helen Varekamp are volunteers from the Canadian Coalition for Invasive Plant Regulation