Crabgrass.

At a glance

Care level

Easy

Plant type

Annual grass

Light

Full sun

Indoor light

direct

Water

Every 3 to 7 days

Mature size

Up to 60 cm tall

Growth rate

fast

Hardiness

USDA 3 to 10

Bloom time

Mid summer to early autumn

Care

Control this weed by maintaining a thick, healthy lawn to shade out seedlings. If you spot it, pull it by hand before it drops seeds. Watch for new sprouts in early spring when soil warms up.

Watering

Keep soil moist for germination but it tolerates drought once established.

Feeding

Does not require intentional fertilization.

Pruning

Mowing prevents seed head formation.

Repotting

This is a wild weed and not typically potted.

Soil

Well-draining, disturbed soil

Soil pH

5.0 to 7.5

Temperature

5 to 35°C

Humidity

30 to 80%

Drought tolerance

high

Lifespan

Annual, typically 1 season

Safety

People

It is not considered toxic to humans.

Pets

This plant is generally considered non-toxic to cats and dogs.

Children

The sharp, pointed seed heads can be irritating if they get stuck in clothing or skin, so keep an eye on small children playing in patches.

Contact allergens

The rough, hairy leaf blades can cause minor skin irritation or contact dermatitis in sensitive individuals.

Airborne allergens

The pollen is a common seasonal allergen for many people during late summer.

Edibility

While the seeds are technically edible, they are tiny, labor intensive to harvest, and often contaminated by soil pathogens or herbicides.

How to identify it

• Spreading, prostrate growth habit
• Light green, hairy leaf blades
• Finger like seed head clusters
• Forms dense, low mats

Height

0.15 to 0.6m

Spread

0.3 to 0.9m

Leaves

light green, deciduous

Flowers

green, purple, 0.5 to 1cm

Fruit

tan, Autumn

Common problems

• Rust fungus — Appears as reddish brown pustules on the leaves during humid weather.

Growing it

Propagation

seed

When to plant

spring

Overwintering

The plant dies completely with the first hard frost, leaving behind a massive seed bank in the soil.

Because this plant is a highly competitive weed, it is best not to include it in intentional garden guilds.

Grows well with

• Common Purslane — They often share the same disturbed soil habitats and thrive under similar moisture conditions.

Keep away from

• Kentucky Bluegrass — This grass aggressively competes with and is often choked out by the rapid growth of crabgrass.

Similar species

• Smooth Crabgrass — It looks very similar but has hairless leaves and a slightly smaller growth habit.

Science

Family

Poaceae

Genus

Digitaria

Order

Poales

Class

Liliopsida

Native range

Native to Europe and parts of Asia, now naturalized worldwide.

Conservation

It is widely considered an invasive weed in many regions and is not of conservation concern.

It thrives in disturbed soils and open areas where it can quickly outcompete native vegetation for sunlight and nutrients.

Value to wildlife

seed source for birds, forage for small mammals

Pollinators

beetles

Uses

forage for livestock, soil erosion control

Taxonomy resolved against GBIF.

Questions people ask

Is it good for lawns?

Generally no, as it grows rapidly and creates unsightly, coarse clumps that crowd out desirable turf grasses.

How do I get rid of it?

Hand pull before it sets seed or use a pre emergent herbicide in early spring.

Where the name comes from

The genus name Digitaria comes from the Latin word digitus, meaning finger, referring to the finger like arrangement of the seed spikes. The species name sanguinalis means blood red, describing the plant's color.

Good to know

• The name sanguinalis refers to the reddish, blood like tint the leaves often develop as they mature.
• It is one of the most widespread weeds in agricultural fields across the globe.
• Seeds can remain viable in the soil for several years.