Flaxleaf fleabane (Erigeron bonariensis) is an annual plant with distinctive blue-green foliage. Flaxleaf fleabane is considered a weed. This species is often found growing along concrete cracks in driveways and sidewalks. It is also found in pastures, gardens and roadsides. Flaxleaf fleabane produces many seeds, which are dispersed by wind and transported by animals, vehicles and people.
I. Appearance and Characteristics
Erigeron bonariensis is a species in the family Asteraceae, found throughout the tropics and subtropics as a pioneer plant; its precise origin is unknown, but most likely it stems from Central America or South America. It has become naturalized in many other regions, including North America, Europe and Australia.
Common names of E. bonariensis include flax-leaf fleabane, wavy-leaf fleabane, Argentine fleabane, Flax Leaved Horseweed, hairy horseweed, asthma weed and hairy fleabane.
Erigeron bonariensis grows up to 75 cm (29.5 in) in height and its leaves are covered with stiff hairs, including long hairs near the apex of the bracts. Its flower heads have white ray florets and yellow disc florets. It can easily be confused with Erigeron canadensis, which grows taller, and E. sumatrensis.
It flowers in August and continues fruiting until the first frosts. It is instantly recognisable by its blue-green foliage, very narrow, undulate stem-leaves, and purple-tipped involucral bracts. It reproduces only by seed, which are easily blown and spread by wind.
Flaxleaf fleabane can cause dermatitis in some people when direct contact is made between any part of the plant and the skin, so it would be advisable to use protective equipment such as gloves and wear long sleeves when handling this plant. Evidence has also shown that flaxleaf fleabane can trigger hay fever, which may result in a runny nose, streaming or itchy eyes, an itchy nose, throat, mouth and ears, headache, earache, temporary loss of smell, and lethargy.
II. How to Grow and Care
Flaxleaf fleabane is a hardy weed known for its resilience and low maintenance requirements. It flourishes in a range of soil types, suggesting it’s not particularly demanding when it comes to soil conditions. A special care point for flaxleaf fleabane is to manage its invasiveness, as it can spread rapidly and may require regular weeding or control measures. The simplicity of basic care combined with control efforts categorizes flaxleaf fleabane as easy to care for.
Sunlight
Flaxleaf fleabane thrives in full sun conditions where it can soak up the sun’s rays for at least six to eight hours per day. While flaxleaf fleabane prefers this level of intense light, it displays a commendable tolerance for partial sun. However, under lower light, it may exhibit reduced vigor and sparse flowering. Flaxleaf fleabane possesses adaptive traits that allow it to manage light stress, where leaves may adjust to optimize light absorption. It is best cultivated outdoors in open, sunny areas where it can achieve optimal growth and maintain robust health. Placing flaxleaf fleabane in an environment that replicates its preferred light intensity is crucial for its development.
Watering
Flaxleaf fleabane thrives in conditions that mimic its native habitat, which often includes well-drained soils and a moderate level of moisture. It has adapted to be relatively drought-tolerant, preferring occasional deep watering to frequent light sprinkles. Accordingly, flaxleaf fleabane benefits from watering every week to maintain its health without over-saturating the soil. Typically grown outdoors due to its resilience, flaxleaf fleabane flourishes when rainfall patterns align with its growth cycles, supplementing irrigation needs naturally.
Soil
Although horseweed can grow in a variety of soil types, it thrives in rich, loamy soil. Mix equal parts sand, clay, and organic material, or use regular soil that has been improved with some perlite to create loamy soil.
Fertilizing
The use of fertilizer is unnecessary. After a year or two, with or without plant food, the plant should have reached its full height.
Propagation
- The plant can be divided by cutting off a healthy branch or digging it up and separating it at its roots.
- Dip the cuttings in the hormone used to help them root.
- You can use regular potting soil or the garden bed to plant the divided plants or cuttings.
- Avoid letting the soil fully dry out as the seedlings establish themselves and new growth emerges.
- The seeds can also be planted in the ground.
Transplanting
To achieve optimal transplanting success, flaxleaf fleabane should be translocated ideally during late spring to early summer (S10-S12). This timing ensures minimal stress and promotes effective root establishment. Select a sunny location for the transplant, as flaxleaf fleabane thrives in full sun. Remember, generous watering post-transplant can help the plant settle in the new spot better.
Pests and Diseases
- The plants are notorious for attracting spider mites when grown indoors.
- In dry climates, these pests may also attack the plants grown outdoors.
III. Uses and Benefits
- Medicinal uses
Crushing the flowers of E. canadensis and putting them up one’s nose is a tried and true method for relieving rhinitis symptoms through sneezing.
A leaf decoction from this plant is used to cure a sore throat or dysentery.
