Brown knapweed (Centaurea jacea)

Brown knapweed

Also known as: Meadow knapweed, Julian knapweed

Brown knapweed (Centaurea jacea) is a perennial flowering plant that grows in woodland clearings, yards, ditches, and pastures. Brown knapweed is native to Europe. This plant is categorized as an invasive species in most places where it grows.

Scientific classification

Species

Brown knapweed (Centaurea jacea)

Asters bellflowers fanflowers and allies

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Weeds

Weed or not

Perennial

Lifespan

Herb

Plant Type

Late spring, Summer, Fall

Bloom Time

Late spring, Summer, Early fall, Mid fall, Early winter

Harvest Time

10 cm to 80 cm

Plant Height

40 cm to 60 cm

Spread

Green, Gray, Silver, Purple

Stem Color

Winter dormancy

Dormancy

Deciduous

Leaf type

10 - 35 ℃

Ideal Temperature

Images of Brown knapweed

Distribution of Brown knapweed

Distribution Map

Brown knapweed is native to Europe, the Mediterranean basin, and eastern Russia. It has been introduced into parts of North America and Australia. This herbaceous perennial grows in open woodlands and grasslands. It is considered an invasive plant in parts of the United States.

Native

Cultivated

Invasive

Introduced

No species reported

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Habitat

Hedgerows, uncultivated land, waste ground

Hemisphere Trend Curve

Northern

Sorthern

Culture

Symbolism

Hope, remembrance, devotion, delicacy, anticipation, unity, fertility and love, also wealth, prosperity and future

Name Story

Brown knapweed: The specific epithet jacea, comes from the Spanish name Knapweed. The plant is featured with brown involucre below the flowerhead, so it is called brown knapweed.

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Weed Control

Native to Eurasia, brown knapweed has been introduced to North America and is listed as invasive in several states throughout the United States. Brown knapweed can act as an alternative host for agricultural pests. It also outcompetes native species by reproducing aggressively and quickly forming deep taproots that can reduce nutrient and water availability. Hand pulling can be effective at controlling populations of brown knapweed if the root is removed. Mowing is typically not effective at reducing populations. Herbicide, grazing, plastic mulching, and a specific species of fly can also be used as effective means of control.

How to Control It

The best season for the removal of brown knapweed is in early spring. It is vital to attend to this plant before it reaches the blooming stage to prevent it from seeding and spreading further. Here are some organic or interesting methodologies to control brown knapweed:

Hand Pulling: This involves physically removing the plant from the ground. Make sure to get the entire root system to prevent regrowth. This can be a time-consuming method, but it is effective and easy to manage in small infestations.
Smothering: Lay down a thick layer of cardboard or newspaper around the plants to block sunlight and prevent growth. This can be topped with a layer of mulch for extra effectiveness. Remember to replace it as it decomposes.
Planting Competition: Plant vigorous, fast-growing plants that can outcompete brown knapweed for resources. Indigenous plants are usually a good option as they are adapted to local conditions and can prevent the growth of brown knapweed.
Using Animals: Certain livestock like goats and sheep can help control brown knapweed as they enjoy feeding on these plants. This method, however, requires monitoring to ensure that the animals don't overgraze the area.
Organic Herbicides: Use vinegar or citrus oil-based herbicides for spot treatment. These products are readily available at garden supply stores. Be sure to spray only on the unwanted plant as it can harm your desirable garden plants as well.

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Care Guide for Brown knapweed

Every week

Water

Full sun

Sunlight

10 - 35 ℃

Ideal Temperature

Garden Soil

Soil Type

Water: Brown knapweed prefers moderate moisture and consistent soil hydration without waterlogging. Weekly watering aligns with its natural rhythm, influenced by seasonal rainfall in temperate regions, essential for its growth cycle and overall health.

Fertilize: Brown knapweed thrives in infertile soils but benefits from proper nutrition to enhance flowering. Apply a base fertilizer before sowing, with nitrogen during the vegetative phase. Phosphorus and potassium fertilizers should be used two weeks before blooming, but avoid over-fertilization to prevent weed growth.

Pruning: To enhance flower size, trim terminal buds of brown knapweed to limit side branches. In mid-summer, when leaves may yellow, prune brown knapweed by one-third to one-half. Additionally, cut perennial roots in winter to protect brown knapweed from cold and frost.

Propagation: Brown knapweed propagates best when sown in spring. Successful growth is indicated by careful monitoring of seedlings and foliage. Ensure the plants are in well-drained soil and receive adequate light for optimal development.

Repotting: Repot brown knapweed every 2-3 years in spring, using a pot 5-8 cm (2-3 inches) larger. Post-repotting, water moderately with good drainage and sunlight to support recovery. Utilize a high-quality potting mix for healthy growth.

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Images of Brown knapweed

Distribution of Brown knapweed

Culture

Weed Control

Care Guide for Brown knapweed

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