Erigeron canadensis [er-IJ-er-on, ka-na-DEN-sis] is an annual found natively throughout most of Central and North America.
It belongs to the family Asteraceae and the large Erigeron plant genus.
Erigeron canadensis goes by several common names:
- Canadian horseweed
- Canadian fleabane
- Colt’s tail
- Mare’s tail
People sometimes mistake the large flowers of Erigeron plants for daisies or asters.
Erigeron canadensis produces white or pale purple flowers and is easily grown indoors or outdoors.
Erigeron Canadensis Care
Size and Growth
Horseweed is an annual weed. It’s a fast-growing plant, typically reaching a height of 60″ inches within one or two seasons.
It produces tall, hairy stems sparsely covered in unstalked leaves and flowering branches.
The leaves are slender, measuring between 1″ inch and 4″ inches and featuring coarsely toothed margins.
They appear in alternate spirals along the stem.
Flowering and Fragrance
- Erigeron canadensis produces a dense cluster of flowers in mid-summer to early fall.
- The blooming period typically only lasts about two to three weeks.
- The flowers are often light green with white or pale purple florets.
- They appear at the ends of the branches.
- After the blooming period, the flowers are replaced by seeds containing fine bristles.
- Wind helps carry the seeds, allowing the plant to propagate freely.
Light and Temperature
Horseweed grows easily almost anywhere in North America but grows rapidly in warm, dry locations.
Grow the plant in full sun when grown outdoors.
It can tolerate direct afternoon sunlight outdoors, especially when grown in a humid region.
When grown indoors, avoid placing it near a south-facing or west-facing window getting lots of direct afternoon sunlight.
Watering and Feeding
- Water occasionally, but avoid overwatering.
- The plant can tolerate drought and prefers slightly drier conditions.
- Fertilizer isn’t needed.
- The plant will likely reach its full height within one or two years with or without plant food.
- During the winter, the plant only needs water when the lower leaves start to wither away.
Soil and Transplanting
Horseweed will grow in almost any soil but thrives in fertile, loamy soil.
- To make loamy soil, combine equal parts sand, clay, and organic material or regular soil enhanced with some perlite.
- Transplanting isn’t needed unless the plant starts to take over part of a garden or yard.
- It can propagate freely and overtake other plants.
- To save the weedy plant, transplant in the spring before the rapid growth starts in the summer.
To manage growth, trim the plant back at any time of the year.
How To Propagate Canadian Horseweed
Propagate by division, seeds, or cuttings.
- Harvest seeds directly from the plant after the flowers fade.
- When the bristly seeds appear, cover them in plastic and wait for them to dry.
- After the seeds dry, trim the connected branches and store seeds overwinter in an envelope.
- Sow the seeds the following spring in standard potting soil in a starter tray.
- Keep the soil moist as the seedlings appear.
- When leaves start to appear, transplant the plants to permanent homes.
- It’s also possible to sow the seeds directly in the soil.
To grow from cuttings or division
- Remove a healthy branch from the plant or dig the plant up and divide it at the base
- Dip cuttings in the rooting hormone.
- Plant the divided plants or cuttings in regular potting soil or directly in the garden bed.
- Keep moist as the young plants take root and new growth appears but avoid overwatering.
Canadian Horseweed Pest or Diseases
- When grown indoors, the plant tends to attract spider mites.
- These pests may also appear on outdoor plants in dry regions.
- Spraying the plant with cold water is a common treatment but may damage the thin stems of the horseweed plant.
- To save the plant, use a miticide or propagate parts of the plant not yet infested.
- Along with pests and diseases, consider where it’s grown.
In Ohio, the plant is considered a noxious weed.
Infestations of the plant have reduced soybean field yields and other harvests in the region.
While it’s a weed, Erigeron canadensis isn’t considered invasive in other regions.
- Keeping the plant away from children and pets is also a good idea.
- The foliage may irritate skin.
- If ingested, parts of the plant may also cause gastrointestinal distress.
- In the wild, horses know to avoid the plant due to its bitter taste.
Suggested Erigeron Canadensis Uses
Horseweed isn’t a commonly grown houseplant as it’s often thought of as a weed.
However, some people enjoy growing it in the kitchen as an herbal plant.
Despite the mild toxicity, the dried leaves provide a flavor comparable to tarragon.
When grown outdoors, horseweed can help attract butterflies, bees, and insect pollinators.
It also appears in the wild growing near pastures, fences, abandoned fields, construction sites, and anywhere with exposed topsoil.