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Ragweed

By Author Matt Cunningham

Posted on  - Last updated:

If you suffer from allergies, then you know about ragweed.  Specifically, you know what a nightmare it is when this plant shows up and grows wild.

If you’re a gardener with allergies, then you’ll definitely want to know how to spot ragweed in your garden and how to get rid of it.

Keep reading to learn about ragweed, the allergies it causes, and how to identify and eliminate it from your garden or landscape.

Closeup of a ragweed plant.

What is Ragweed?

Ragweed is a flowering plant belonging to the Asteraceae family. It’s infamous for causing hay fever and allergic reactions in susceptible individuals. The plant’s pollen triggers seasonal allergies, especially during late summer and early fall.

With around 50 species worldwide, ragweed plants are predominantly found in North America. 

Closeup of flowers on a giant ragweed plant.
Flowers on giant ragweed.

The Different Types of Ragweed

Though there are many ragweed species, the most common ones associated with allergies are:

  1. Common ragweed (Ambrosia artemisiifolia)
  2. Giant ragweed (Ambrosia trifida)
  3. Western ragweed (Ambrosia psilostachya)
  4. Perennial ragweed (Ambrosia coronopifolia)

Each species exhibits different characteristics and growth patterns, but all share the ability to release copious amounts of pollen.

Ragweed Allergies

Closeup of ragweed flowers and pollen.

Symptoms of Ragweed Allergies

Ragweed pollen causes allergic reactions in many people. Symptoms can vary in severity and may include:

  • Sneezing
  • Runny or stuffy nose
  • Itchy or watery eyes
  • Itchy throat
  • Fatigue
  • Headache
  • Asthma exacerbation

Diagnosis and Testing

If you suspect a ragweed allergy, consult an allergist for testing. Skin prick tests and blood tests are common diagnostic tools for detecting specific allergens.

Treatment Options for Ragweed Allergies

There are several treatment options available for managing ragweed allergy symptoms:

  1. Antihistamines: These medications help relieve sneezing, itching, and a runny nose.
  2. Decongestants: These drugs help clear stuffy noses and sinus congestion.
  3. Nasal corticosteroids: These prescription sprays reduce inflammation in the nasal passages.
  4. Immunotherapy: Allergy shots or sublingual tablets can help build immunity to allergens over time.

Ragweed Pollination and Distribution

Stalks of flowers on a low ragweed plant.
Low ragweed variety.

Pollination Process

Ragweed plants are wind-pollinated, meaning that they release pollen into the air, which is then carried by the wind to other plants for fertilization. Each ragweed plant can produce up to one billion pollen grains per season.  Ragweed is one of the most, if not the most, allergenic plants around.

Factors Affecting Pollen Distribution

Various factors, including weather conditions, geographic location, and time of day influence pollen distribution. Warm, dry, and windy days increase pollen levels, while cooler, damp, and rainy days decrease pollen dispersal. Additionally, pollen counts are usually higher in the early morning and late afternoon.

Controlling Ragweed Growth

Ragweed plants with flowers starting to form.

Cultural Control Methods

To prevent ragweed growth and reduce its impact on allergy sufferers, several cultural control methods can be employed:

  1. Mowing and trimming: Regularly mow lawns and trim edges to prevent ragweed from flowering and releasing pollen.
  2. Hand-pulling: Remove ragweed plants before they flower, ensuring you remove the entire root system.
  3. Planting ground cover: Establishing dense ground cover or turf can outcompete ragweed and limit its growth.
  4. Mulching: Applying a layer of mulch can suppress weed growth by blocking sunlight.
  5. Monitoring: Regularly inspect gardens and outdoor spaces for new ragweed growth and take action when necessary.

Chemical Control Methods

When cultural control methods are insufficient, chemical control methods can be used as a supplementary measure:

  1. Pre-emergent herbicides: These chemicals prevent ragweed seeds from germinating and can be applied in early spring.
  2. Post-emergent herbicides: These are applied to actively growing ragweed plants and are most effective when the plant is young and not yet flowering.

Ragweed’s Impact on Agriculture and the Environment

Ragweed plants and flowers in the sun.

Impact on Crop Production

Ragweed poses a threat to agriculture, as it can compete with crops for nutrients, water, and sunlight. Additionally, ragweed pollen can contaminate certain crops, lowering their quality and market value.

Ragweed’s Role in Soil Erosion and Biodiversity

Ragweed’s rapid growth and quick spread can contribute to soil erosion, particularly in areas with little ground cover. Furthermore, ragweed can disrupt local ecosystems by outcompeting native plants and reducing biodiversity.

Frequently Asked Questions About Ragweed

A bouquet of ragweed.

What is the peak ragweed pollen season?

The peak ragweed pollen season typically occurs from late summer to early fall, with August and September being the worst months for allergy sufferers.

How far can ragweed pollen travel?

Ragweed pollen can travel hundreds of miles, depending on wind conditions and other factors. It is not uncommon for pollen to cross state lines or even countries.

How can I reduce my exposure to ragweed pollen?

To reduce exposure to ragweed pollen, consider staying indoors during peak pollen times, using air filters in your home, and changing clothes and showering after spending time outdoors.

Are there any natural remedies for ragweed allergies?

Some people find relief from ragweed allergies with natural remedies such as butterbur, quercetin, and stinging nettle. However, it is essential to consult a healthcare professional before starting any new treatment.

Can ragweed allergies be cured?

There is no cure for ragweed allergies, but symptoms can be managed with medications, immunotherapy, and preventive measures to limit exposure to pollen.

Is there anything beneficial about ragweed?

Surprisingly, yes. Ragweed has astrigent and antiseptic properties.  It can be used in herbal and homeopathic remedies for nausea, fever, menstrual pain, insect bites, and nosebleeds. 

Pollen from some ragweed varieties is even used in commercial medications to treat hay fever caused by – you guessed it – ragweed.

The Annual Unwelcome Garden Visitor

Closeup of a ragweed plant backlit by evening sun.

Ragweed is a common cause of seasonal allergies and can negatively impact agriculture and the environment. Controlling ragweed growth is essential to minimize its effects on human health, crop production, and local ecosystems. By combining cultural and chemical control methods, we can help reduce ragweed’s impact on our daily lives.

If you feel like you need to learn more about these pesky garden tenants, check out our weeds page to learn all about different weed varieties, treatment options, and surprising information.