Ragweed (Ambrosia Artemisiifolia) Growing, Care, & Removal Guide for Gardeners
Article by Dean Ravenscroft, Ph.D. - Updated 31st Jan 2024
- Plant Characteristics: Recognized for its feathery, fern-like leaves and small, greenish flowers. This annual plant is notorious for its highly allergenic pollen, making it a concern for people with allergies.
- Growing & Care: Thrives in disturbed soils and is commonly found in fields, gardens, and roadside areas. It's drought-tolerant and can grow in a variety of soil conditions, but managing its spread is crucial due to its allergenic properties.
- Tips for New Gardeners: While easy to grow, Common Ragweed is generally not recommended for cultivation due to its aggressive nature and the health issues caused by its pollen. Gardeners should be cautious and consider removing it to prevent allergic reactions.
Ambrosia Artemisiifolia, better known as Common Ragweed, is one of the most commonly seen members of the Daisy family in the USA.
The widespread growing nature of Common Ragweed across North America has seen it classified by many farmers and gardeners as a weed that should be removed if possible.
Natively growing Ambrosia-artemisiifolia plant, photograph by Harry Rose; CC.
It is also considered as an invasive species in many other parts of the world.
The plant seems to be less invasive in cooler climates. This is because it produces less flowers and seeds do not ripen as well in the cold.
Ambrosia Artemisiifolia is also problematic for many people because of the high levels of pollen it produces. This is known to cause allergies in many people, and even touching the plant itself can cause itchiness and eye irritations.
Ambrosia artemisiifolia photograph by Radu Chibzii.
That said, many gardeners are happy to use Common Ragweed in their yards. This is because this plant has a long tradition of use to attract various insects (which feed on it). It also attracts honey bees, which are important pollinators for this plant. Thus some gardeners use this plant as a patch of wild garden to help encourage nature to their gardens.
Birds, especially game birds, can also be attracted to the seeds of Common Ragweed because they enjoy the oily seeds that are produced.
Ambrosia Artemisiifolia Growing Guide
Nearly all soil types can be used to grow Ambrosia Artemisiifolia with this plant being tolerant of dry to average moisture levels.
If left unchecked the Common Ragweed is a plant that can grow high and uncontrollably. Reaching heights of three to seven feet tall (0.9 to 2.1 m), with a similar width.
Flowers of the Common Ragweed are green with deep green opposite leaves. Stems are hairy. Plants produce flowers from mid-Summer through to the Fall.
Ambrosia Artemisiifolia grows upright with erect hairy stems reaching high into the air. This can make it ideal for adding some height to the the back of the garden.
Common Ragweed photograph by Andreas Rockstein; CC.
Ambrosia Artemisiifolia Gardening Questions
What is Ambrosia Artemisiifolia
More commonly known as Common Ragweed, Ambrosia Artemisiifolia is a flowering plant that is usually considered a weed, and is invasive in many parts of the world. The pollen a known source of allergies.
It is not usually grown in gardens as it can spread rapidly from its tubers and readily appears in lawns and beds.
Why grow Ragweed in the garden?
It's main use in a garden is as part of wild plant section used to attract birds and insects to the garden.
It's pollen is collected by honey bees, so is a great plant to grow (under control) in areas where bees are in decline.
Will Vinegar kill Ragweed?
Acetic acid can be used as an herbicide on young plants if deployed at high concentrations - typically four times as concentrated (20%+ acetic acid) as is found in shop bought vinegar (~5% acetic acid).
How to get rid of Ragweed
Depending on where they are growing you may wish to use a herbicide or remove by hand.
If they are growing in your vegetable patches then use a hoe to remove them. You will need to frequently how new growth as they grow from buried tubers. Over time they should stop appearing.
In beds, you can pull up ragweed by hand. Be sure to use gloves as these plants have spikes and can cause allergies. If plants are already producing pollen you may also wish to use a face mask when removing Ambrosia Artemisiifolia from the garden.
If Ragweed is affecting your lawn, then simply mow over them; they will lose their vigor over time. You can also apply a broad leaf herbicide.
If using a herbicide, then either use glyphosate, or one aimed at broad leaf plants. Apply when the plants are small (middle of spring through to the start of summer). Larger plants will require multiple applications.
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Ambrosia artemisiifolia Growing and Care Guide
- Scientific Name: Ambrosia artemisiifolia.
- Common Name: Ragweed, Bitterweed.
- Life Cycle / Plant Type: Annual Herb.
- Native: North and Central America.
- Growing Zone: Plants do not tolerate frost. USA: 6 to 10. UK RHS H2.
Plant Details
- Plant Height: 3 to 8 feet (90 to 240 cm).
- Plant Spread (Inches): 3 to 7 feet (90 to 210 cm).
- Time of Bloom: Mid-summer to mid-autumn.
- Flower Details: Green, inverted racemes, small drooping flower heads, slender.
- Leaf Foliage: Green, 1.5 to 4 inches long (4 to 10 cm), Compound, upper surface is hairy.
- Fruit: yellow to brown, woody.
- Growth Form: Upright / erect.
Ideal Growing Conditions
- Best Light Conditions: Partially shady to full sunlight.
- Rate of Growth: Average pace.
- Suitable Soil Types: Adaptable, Clay, Loamy, Sandy, Well drained. The ideal soil condition for Ambrosia artemisiifolia to grow well is wet, heavy, and a slightly acidic to neutral pH.
- Soil Moisture: Dry to Moist (Medium Moisture is likely gives best results).
Caring Conditions
- Care: As the plant tissue causes many weed allergies always use gloves. If you suffer from hayfever then use a facemask when dealing with this plant if it is in bloom.
- Level of Maintenance: Massive to control, low if growing intentionally. These plants can quickly spread via their shallow taproots. Only grow in a controlled area.
- Propagation: Seed Propagates, but not required, will spread abundantly and produces massive amounts of seed.
- How to Remove Ragweed: Hoeing, herbicide, Acetic acid, digging up soil and raking and baking.
- Pests: Silverleaf whitefly, Ragweed borer, Olive-shaded bird-dropping moth, Hyalesthes obsoletus, Ragweed leaf beetle.
- Diseases: Candidatus Phytoplasma solani, Plasmopara halstedii, Puccinia conoclinii, Thanatephorus cucumeris.
Further Information
- Can Attract Wildlife such as: Honeybees, moths, grasshoppers, Birds.
- Tolerant of:.
- Best Garden Use: Weed - Not a garden plant, fine for a wildlife patch in a controlled area.
- Family: Asteraceae (Compositae) (Aster and Daisy).
- Closely Related Species: Other members of this diverse family include Wild Artichoke, the Gazania plant, Leontopodium and even the salad plant lettuce.
- Miscellaneous: North American native, Invasive, Inconspicuous flowers or blooms. Often grown for potential herbalist properties such as the support of nausea and fever, and potential use as a laxative. Known to be one of the main causes of Hay fever.
- Further Reading and References: RHS plant finder and Illionos Wild Flowers.
Picture of Ragweed leaves by Gilles San Martin; CC.
I hope that you enjoyed this guide on how to grow Ambrosia artemisiifolia. You may also enjoy the following growing guides:
Ambrosia (Muskmelon variety). Other annual herbs covered on the site include: How to grow Dill and Basil plants.
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