How to Grow and Control Ambrosia Artemisiifolia Plants in your Garden

Gardener's HQ Guide to Common Ragweed

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.

Ragweed

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.

Ragweed

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 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/p>

Will Vigengar kill Ragweed?

Acetic acid can be used as an herbicide on young plants if deployed at high concentrations - tyically four times as concentrated (20%+ acetic acid) as is found in shop bought vinegars (~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 burried tubers. Over time they should stop appearing.

In beds, you can pullup 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 facemask when removing Ambrosia Artemisiifolia from the garden.

If Ragweed is affecting your lawn, then simply mow over them; they will lose their vigour over time. You can also apply a broadleaf 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 rquire multiple applications.

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.

Ragweed

Common Ragweed photograph by Andreas Rockstein; CC.

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 abudantly 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 laxitive. Known to be one of the main causes of Hay fever.
Further Reading and References: RHS plant finder and Illionos Wild Flowers