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Annual KnawelScleranthus annuus

Also known as German Knotgrass · German Knotwort · German Moss

  • Type: Herb
  • Sunlight: Full Sun
  • Water: Moderate
  • Temperature: Moderate

Annual Knawel (Scleranthus annuus) is a low-growing annual herb with tiny, star-shaped white flowers. It thrives in dry, sandy soils and open habitats.

Scleranthus annuus, commonly known as Annual Knawel, is a low-growing herbaceous plant belonging to the Caryophyllaceae family. This species is notable for its dense, mat-forming habit and its role in various ecosystems. It is an annual, meaning it completes its life cycle within a single growing season, germinating, flowering, and producing seeds before dying. Physically, Scleranthus annuus is characterized by its prostrate to ascending growth. Stems are typically short, branching from the base, and can reach lengths of up to 20 centimeters, though they often remain much shorter, forming compact cushions. The leaves are small, linear to awl-shaped, and arranged oppositely along the stems. They are typically 3-8 millimeters long, pointed, and sessile, meaning they lack a stalk. The plant produces small, inconspicuous flowers that are greenish or whitish, lacking petals and sepals in the traditional sense. Instead, the flower is surrounded by five prominent, green, leaf-like bracts that enclose the reproductive parts. These flowers are borne singly or in dense clusters in the leaf axils. The fruit is a small, indehiscent capsule that remains enclosed within the persistent calyx. Seeds are typically ovoid and smooth. The native distribution of Scleranthus annuus is widespread across Europe and parts of Asia, extending into North Africa. It is often found in disturbed habitats, such as sandy fields, roadsides, waste areas, and open, dry grasslands. It prefers well-drained soils and full sun exposure. While it is an annual, its ability to self-seed allows it to persist in suitable environments. Cultivation requirements are minimal, as it thrives in poor, sandy soils and tolerates drought once established. It is not typically cultivated for ornamental purposes due to its small size and inconspicuous flowers, but its groundcover habit can be useful in specific ecological restoration contexts or as a component of wildflower mixes. Ecologically, Scleranthus annuus plays a role in stabilizing soil in its native habitats and can be a food source for certain insects. Its ability to colonize disturbed and nutrient-poor sites highlights its resilience. There are no widely established or scientifically documented uses in agriculture, medicine, or culinary practices for Scleranthus annuus. Its primary significance lies in its botanical characteristics and its presence within its natural range. An interesting adaptation of Scleranthus annuus is its flower structure, where the prominent bracts mimic petals, potentially attracting pollinators to the small, apetalous flowers. The plant's ability to thrive in dry, sandy conditions is also a key characteristic, indicating adaptations for water conservation.

Photograph © Marcelo Amores Palma · CC-BY-NC

Annual Knawel Care Summary

At-a-glance light, water, soil, and growing conditions from plant data

Light

Full Sun

100% intensity

Prefers at least 6 hours of direct sunlight daily.

Water

Moderate

50% intensity

Keep soil consistently moist but not waterlogged.

Soil

Sandy, Loam, Acidic, Neutral, Alkaline

50% intensity

Temperature

Moderate

50% intensity

Thrives in average room temperatures; avoid extreme heat or cold.

Fertilizer

Low

25% intensity

Does not require frequent fertilization; light feeding may be beneficial.

Annual Knawel Toxicity

Safety information from plant toxicity data

Toxicity details for Annual Knawel
AttributeValue
Toxic for humansNo

0/5 intensity

Toxic for petsNo

0/5 intensity

EdibleNo

Annual Knawel Quick Facts

Key traits and growing stats from plant data

Plant Type
Herb
Plant Place Type
Garden, Pot
Lifespan
Annual
Plant Height
0.05-0.2 m
Spread
0.1-0.3 m
Growth Rate
Moderate
Dormancy
None
Leaf Color
Green
Leaf Type
Linear
Flower Size
Small
Optimal Sunlight Lux
60000
Weed Status
Yes

Care guide for Annual Knawel

Watering, pruning, propagation, and repotting details from plant data

Water

Annual Knawel prefers consistently moist soil, especially during establishment and active growth. Water thoroughly when the top centimeter of soil feels dry. Avoid waterlogging, as this can lead to root rot.

Reduce watering in cooler months or when the plant is dormant.

Pruning

Pruning is usually not necessary for Annual Knawel, as it is a self-limiting annual. If desired, light trimming can be done after flowering to tidy up the appearance or to prevent excessive self-seeding.

Remove any dead or damaged stems at any time.

Propagation

Annual Knawel is easily propagated by seed. Sow seeds directly outdoors in early spring after the last frost, or start them indoors a few weeks prior.

Seeds require light to germinate, so sow them on the surface of the soil.

Repotting

As an annual, Annual Knawel is typically not repotted. It completes its life cycle within a single growing season.

If grown in containers, the entire plant with its soil is usually discarded after flowering or at the end of the season.

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Flowering & Fruiting Cycles

Monthly activity intensity for bloom and fruit across both hemispheres.

Northern hemisphere

Flowering & fruiting calendar

Peak bloom · JunPeak fruit · Jul
FloweringFruiting
02468JanFebMarAprMayJunJulAugSepOctNovDecActivity intensityMonths88
Southern hemisphere

Flowering & fruiting calendar

Peak bloom · JunPeak fruit · Jul
FloweringFruiting
02468JanFebMarAprMayJunJulAugSepOctNovDecActivity intensityMonths88

Annual Knawel Names & Synonyms

Common names and botanical synonyms

Common Names

  • Annual Knawel
  • German Knotgrass
  • German Knotwort
  • German Moss
  • German-Knotweed
  • Knawel

Synonyms

  • Knavel annuum (L.) Scop.

Annual Knawel Taxonomy

Botanical classification

Taxonomic classification of Annual Knawel
RankName
kingdomPlantae
divisionTracheophyta
classMagnoliopsida
orderCaryophyllales
familyCaryophyllaceae
genusScleranthus
speciesScleranthus annuus

Annual Knawel FAQs

Answers based on plant encyclopedia data

What are the preferred soil conditions for Annual Knawel?

Annual Knawel prefers well-drained, sandy or gravelly soils. It is tolerant of poor, dry conditions.

How much sunlight does Annual Knawel need?

Annual Knawel thrives in full sun.

Is Annual Knawel invasive?

While it can self-seed readily, Annual Knawel is not typically considered highly invasive in most regions, especially in its native or naturalized range.

When does Annual Knawel flower?

Annual Knawel typically flowers from late spring through summer.

What is the growth habit of Annual Knawel?

Annual Knawel forms a low, mat-forming habit, growing only a few centimeters in height.