Agricultural News

Daisies in Disguise: The Hidden Threat to Alberta’s Ecosystem 

Tuesday, July 1, 2025

Did you know that any white daisy you see in Alberta is not a native plant species? While some varieties are available in stores for gardening, it’s important to be cautious about what you plant. Two highly invasive species – Oxeye daisy (Leucanthemum vulgare) and Scentless chamomile (Tripleurospermum inodorum) – are both listed as noxious weeds under Alberta’s Weed Control Act.  

Many people, unaware of the harm caused to the local ecosystem, unintentionally contribute to the spread of invasive species by planting or spreading oxeye daisy and scentless chamomile. These species are frequently mistaken for the ornamental Shasta daisy (Leucanthemum x superbum), further aiding their spread. 

Another common way these invasive daisies spread is through wildflower seed mixes. Avoid planting mixes that do not clearly list the species, as they often contain invasive plants. Taking a moment to read the scientific names can help ensure you’re planting species that are truly native and safe for Alberta’s ecosystems. 

Oxeye Daisy: A Charming but Relentless Invader 

Oxeye daisy (Leucanthemum vulgare) is a perennial weed that thrives in various habitats, especially in nutrient-poor soils. Despite its charming appearance, it aggressively outcompetes native plants and pasture species. 

A single oxeye daisy plant can produce up to 26,000 seeds, which remain viable in the soil for more than a decade. Additionally, it spreads through underground rhizomes, making control difficult once established. 

Controlling Oxeye Daisy 

• Prevention: The most effective way to control oxeye daisy is by preventing its establishment through early detection, maintaining healthy vegetation, and minimizing soil disturbance. 
• Mowing & Deadheading: Provides temporary control by preventing seed spread. Whenever possible, dispose of seed heads in the trash to help reduce the seed bank on-site. 
• Herbicides: The most effective method involves applying products containing Metsulfuron-methyl or 2,4-D before flowering, as seeds become viable just 10 days after flowering begins. Always read and carefully follow the directions outlined on the herbicide label. 

Scentless Chamomile: A Pretty Disguise for a Seedy Threat 

Scentless chamomile (Tripleurospermum inodorum) is another invasive species, commonly misidentified as oxeye daisy. Unlike the fragrant chamomile used in tea, this species is completely odorless and is listed as a noxious weed under the Alberta Weed Control Act. 

This weed spreads rapidly, with each plant capable of producing 500,000 seeds that can travel via water, wind, and human activity. It is highly adaptable, tolerating heavy clay soils, drought, and even flooding. Once established in cropland, it can reduce yields by up to 60%. 

Controlling Scentless Chamomile 

• Prevention: Monitor property for new plants and remove them immediately. Avoid disturbance and promoting dense, competitive native vegetation to outcompete the scentless chamomile. 
• Tilling & Hand Pulling: Shallow tilling in late fall and early spring can exhaust the seed bank. Hand pulling is effective but ensure plants are bagged and sent to the landfill. 
• Herbicides: Look for products containing Aminopyralid, alone or mixed with 2,4-D or Metsulfuron-methyl. Always read and carefully follow the directions outlined on the herbicide label. 

Shasta Daisy: A Garden Favourite with Risks 

Shasta daisy (Leucanthemum x superbum) is a popular garden plant created through hybridization, including genes from the invasive oxeye daisy (Leucanthemum). While it is not classified as a noxious weed, Shasta daisy can revert to oxeye daisy, spreading aggressively in gardens and nearby natural areas. 

Preventing the Spread of Shasta Daisy 

To keep your Shasta daisies from turning invasive: 

• Deadhead flowers at the end of summer prior to going to seed 
• Bag and dispose of seed heads in the garbage (not compost) 
• Monitor for excessive spreading 

By taking these precautions, you can enjoy Shasta daisies in your garden without risking the spread of an invasive species. 

Key Identification Differences Between Species 

Native Daisy Alternatives

If you are searching for daisy-like plants for your garden or yard, consider these beautiful native species found in Alberta:

• Alpine Aster (Aster alpinus)
• Pearly Everlasting (Anaphalis margaritacea)
• Smooth Fleabane (Erigeron glabellus)
• Other Fleabanes in the Erigeron family

Dig Deeper

For more information on invasive species and native plants, please see the resources listed below.

Weed Identification

• Alberta Invasive Species Council (AISC) – Website
• AISC Invasive Plant Fact Sheets – Oxeye Daisy, Scentless Chamomile, Other Species
• Association of Alberta Agricultural Fieldmen (AAAF) – Regulated Weed Identification Booklet, Association Involvement in Weed Control
• Rocky View County Report Problem Weeds (For species found on the Weed Control Act) – Online Form

Native Species

• Alberta Native Plant Council – Website
• ALCLA Native Plant Nursery – Website
• Grow Me Instead – Plant Wise Brochure

Posted in: Agriculture