Pocket BotanistPlant guide
Large crabgrass.
Digitaria sanguinalis
Pronounced di-ji-TARE-ee-uh san-gwin-AL-iss
Also known as Crab Finger Grass, Crab-grass, Hairy Finger-grass, Crabgrass, Crap-grass, Crop Grass, Early Crab Grass, Hairy Crabgrass, Hairy Finger Grass
Large crabgrass is a common annual grass that often shows up as a weed in lawns and gardens. It thrives in warm weather and spreads quickly through seeds. You will usually spot it growing in thin or neglected turf areas.
At a glance
- Care level
- Easy
- Plant type
- Annual grass
- Light
- Full sun
- Indoor light
- Direct sun
- Water
- Every 3 to 7 days
- Mature size
- 1 to 3 feet tall
- Growth rate
- Fast
- Hardiness
- USDA 3 to 10
- Bloom time
- Mid summer to early autumn
Care
This plant is typically managed as a weed rather than cultivated. Keep your lawn thick and healthy to prevent seeds from germinating. Watch for patches of light green grass appearing in mid summer.
- Watering
- It prefers moist soil but is quite drought tolerant once established.
- Feeding
- Fertilization is not recommended as it encourages aggressive growth.
- Pruning
- Regular mowing helps prevent seed head formation.
- Repotting
- This plant is not suitable for container cultivation.
- Soil
- Well drained soil
- Soil pH
- 5.0 to 7.5
- Temperature
- 10 to 35°C
- Humidity
- 40 to 80%
- Drought tolerance
- Moderate
- Lifespan
- Annual, typically 1 season.
- Deer and rabbits
- Moderate
Safety
- People
- This plant is not considered toxic to humans.
- Children
- There are no specific safety concerns for children beyond the usual caution regarding ingestion of non food plants.
- Contact allergens
- The foliage can cause mild skin irritation in sensitive individuals due to fine hairs.
- Airborne allergens
- The pollen is a common seasonal allergen for many people.
- Edibility
- While the seeds are technically edible, they are rarely harvested due to their tiny size and the effort required to process them.
How to identify it
- Spreading stems rooting at nodes
- Leaf blades with sparse hairs
- Finger like seed head branches
- Light green foliage color
- Prostrate or ascending growth habit
- Height
- 0.15 to 0.9m
- Spread
- 0.2 to 0.6m
- Leaves
- green, purplish, deciduous
- Flowers
- green, purple, 0.1 to 0.3cm
- Fruit
- tan, Late summer to autumn
Problems to watch for
By symptom
Check your large crabgrass from a photo
Pocket Botanist looks at a photo of your plant and tells you what's wrong and what to try first.
Growing it
- Propagation
- seed
- When to plant
- spring
- Overwintering
- The plant dies completely with the first hard frost, leaving only seeds in the soil to germinate the following spring.
- In containers
- It is not recommended for container use as it is an aggressive weed.
Seed dispersal
- 1. Allow seed heads to mature on the plant until they turn tan.
- 2. Collect the seeds by shaking the heads into a bag.
- 3. Scatter seeds on bare soil in early spring.
It is best to avoid planting this near desired turf grasses as it will compete for resources.
Grows well with
- Common Dandelion — They often share the same disturbed habitats.
Keep away from
- Kentucky Bluegrass — This grass aggressively outcompetes and displaces lawn grasses.
Similar species
- Smooth Crabgrass — It is a very similar species that lacks the coarse hairs found on large crabgrass.
Science
- Family
- Poaceae
- Genus
- Digitaria
- Order
- Poales
- Class
- Liliopsida
- Native range
- Europe and temperate Asia.
- Conservation
- It is considered a widespread and aggressive weed in many regions, not a conservation concern.
It is a pioneer species that quickly colonizes bare or disturbed soil to prevent erosion.
- Value to wildlife
- seed source for birds, ground cover
- Pollinators
- bees, beetles
- Uses
- forage, soil stabilization, wildlife food
Through the year
Ecological indicators
- Soil reaction
- 6/9
- Light
- 8/9
- Temperature
- 7/9
- Moisture
- 5/9
- Nutrients
- 6/9
- Salinity
- 2/9
Taxonomy resolved against GBIF.
Questions people ask
- Is it a good lawn grass?
- No, it is generally considered a troublesome weed in managed turf.
- How do I control it?
- Preventative measures like maintaining a thick lawn canopy or using pre emergent herbicides are most effective.
Where the name comes from
The name Digitaria comes from the Latin word digitus, meaning finger, referring to the finger like arrangement of the seed spikes.
Good to know
- It is commonly known as crabgrass because of its sprawling, crab like growth habit.
- The species name sanguinalis refers to the reddish or blood colored tint the leaves often develop.
- It thrives in disturbed soils and is a frequent invader of lawns and gardens.
Keep your large crabgrass growing
This page is a general guide. Save your plant in Pocket Botanist and you get care reminders timed for this plant, plus a care history that shows what worked.
This guide was generated with AI and checked against GBIF taxonomy. It is general information, not horticultural or veterinary advice. Read about how we build these guides.