Facts about Crab Grass

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Crab Grass Quick Facts
Name: Crab Grass
Scientific Name: Digitaria sanguinalis
Origin Europe or Eurasia and is distributed worldwide
Colors Dark purplish
Shapes Caryopsis enclosed in 2 sterile flowering-glumes, 2-4 mm (0.078 - 0.157 inch) long
Health benefits Beneficial for gonorrhea, cataracts and debility.
Digitaria sanguinalis is a species of grass known by several common names, including hairy crabgrass, hairy finger-grass, large crabgrass, crab finger grass, purple crabgrass. The plant is native to Europe or Eurasia and is distributed worldwide.  It is one of the better-known species of the genus Digitaria, and one that is known nearly worldwide as a common weed. It is used as animal fodder, and the seeds are edible and have been used as a grain in Germany and especially Poland, where it is occasionally cultivated.  This has earned it the name Polish millet. The genus name Digitaria is derived from the Latin digitus, meaning ‘finger’ which refers to the shape of the panicle branches of many of the species. The species name, sanguinalis, is derived from the Latin sanguis meaning ‘blood’, and probably referring to the reddish tinge of the panicle branch rachis.

Plant Description

Crab Grass is an annual, sparse, tufted decumbent, warm season, spreading grass that grows about 3-4 feet tall. The plant is found growing on waste ground, railway embankments, neglected lawns, grassy ridges, rocky, open ground, prairie openings, pastures, row crops, fields, turf, roadsides, gardens, weedy meadows, edges of degraded wetlands, vacant lots, grassy paths, highly disturbed areas and various waste areas. The plant prefers warm, sandy and fine-textured soils which are low in lime, but not in nutrient content. Roots are fibrous, sometimes forming from the nodes of the lower culms. The lower branches of the culms sprawl across the ground, while the upper branches are more erect. Large crabgrass has also been used as forage. Crabgrass is not regulated as a noxious weed in the Mid-South.


Crab grass develops several branching culms at the base; the lower branches of the culms tend to sprawl across the ground, while their upper branches are more erect. The culms are light green, terete and glabrous, although they are mostly covered by the sheaths. The sheaths are light green, finely ribbed, shiny or dull, and hairy. Leaves are numerous near the base of the plant and scattered along the stems. They are soft and smooth, usually hairy near the base, 4-8 mm wide and with an open hairy sheath around the stem. Leaf blades are 4 to 15 cm long and 4 to 12 mm wide. Leaf blade is green to purple, both sides with silky, shiny hairs, often reddish with central strip and pale at the margin. Sheath green to reddish violet with long blister-like hairs, especially at the sheath base. Youngest leaf is rolled.

Flower and fruit

The central stalk of each raceme is light green, flattened, and about 1 mm across. There are many pairs of one-flowered spikelets along the length of each raceme; they occur along only one side of the flattened stalk. Each ovoid spikelet is light green to brownish green, flattened, and about 3 mm. long. The lemmas enclose a single developing grain. The blooming period occurs from August to September. Each grain is ovoid, 2 -2.2 mm long and flattened like the lemmas.

Traditional uses and benefits of Crab grass

  • A decoction of the plant is used in the treatment of gonorrhea.
  • A folk remedy for cataracts and debility, it is also said to be emetic.
  • It is used as folk remedy for cataracts and debility.

Culinary Uses

  • Seed is ground up and used as flour.
  • It makes fine white flour that can be used for semolina.

Crabgrass Muffins



  1. Preheat oven to 350 degrees F.
  2. Place flours and baking soda in bowl, mix in water, eggs, vanilla and oil.
  3. Fold in raisins thoroughly Fill muffin tins 1/2 full or pour in 8 inch square baking pan.
  4. Bake 20 to 25 minutes
  5. Let cool and remove from pan.

Other facts

  • Fiber obtained from the plant is used in making paper.
  • A single plant is capable of producing 150 to 700 tillers and 150,000 seeds.

How to Get Rid of Crabgrass

Controlling Crabgrass before it Comes Up

If crabgrass has become established in your lawn, proper lawn maintenance alone may not be enough. A pre-emergent herbicide is the next line of defense. Pre-emergent herbicides work by killing the crabgrass seedlings as they germinate. When applying the pre-emergent herbicide, always follow the manufacturer’s directions. In general:

  • Timing is vital when using pre-emergent herbicides. Application times depend a great deal on weather patterns, which vary from region to region. If your area has experienced a warmer than usual winter, you’ll probably need to apply the herbicide earlier than usual.
  • Apply the herbicide when the ground temperature rises above 60 degrees. Since it’s hard for most of us to monitor the soil temperature, there’s an easier way. When you notice shrubs blooming and trees budding, it’s time to apply the herbicide. Warm nights and periods of rainfall encourage crabgrass germination. If your weather fits this pattern, get the herbicide in place right away.
  • For newly seeded lawns, wait until you have mowed your lawn three times before applying the herbicide to avoid killing the new grass seedlings.
  • Apply the herbicide consistently across your lawn. If you miss a spot, crabgrass can get established and then spread to the rest of your lawn.
  • Do not de-thatch or ventilate the lawn after applying the herbicide. Doing so may break the chemical barrier of the herbicide.
  • Wait two to four months to re-seed the lawn after using a pre-emergent herbicide.
  • Use a pre-emergent herbicide during late winter or during early spring of the next year to prevent any crabgrass seeds left behind from developing at the next opportunity.
  • Do not use a pre-emergent herbicide if crabgrass is already in the lawn or if you have just installed sod.

Killing Crabgrass after it Comes Up

If the crabgrass seeds have already grown and crabgrass has appeared in your grass, the pre-emergent herbicide will do no good. However, you still have an option. Post-emergent herbicide products control crabgrass after it has already germinated.

Post-emergent herbicides work by killing the crabgrass plants. Apply these herbicides only to the crabgrass that is visible. Read and follow the manufacturer’s directions on the product carefully. The amount of post-emergent herbicide that you can safely apply to your lawn depends on the type of grass you have. Here are some tips:

  • Check the weather forecast before using a post-emergent herbicide. Apply the herbicide on a calm, sunny day. Rainfall shortly after application will wash the product away before the crabgrass has a chance to absorb it.
  • For best results, apply the herbicide in the morning after the dew has dried. If you wait until late afternoon, dew or a shower may prevent maximum absorption.
  • Post-emergent herbicides work best when temperatures are 60 – 90°F. These higher temperatures cause the plants to absorb the herbicide quickly; if the temperatures are too cool or weather conditions are too cloudy, the product is likely to be ineffective.
  • Make sure the soil is moist before applying the herbicide. If not, you should water the area fairly extensively the day before treatment. If conditions are extremely dry, you may want to water again two days after the application. The waiting period will give the crabgrass time to absorb the herbicide.
  • If you notice the lawn browning suddenly, you may have applied too much herbicide. In this case, water the area extensively as soon as possible to dilute the herbicide and keep it from further damaging your lawn.
  • After treating the area with the herbicide, keep an eye out for newly germinated crabgrass plants. Any plants that may have germinated since the initial application will require a follow-up spot treatment.
  • If the crabgrass plants are fairly well established, you’ll need to apply the herbicide twice. Treat the affected areas again four to seven days after the first application. Make sure the soil is moist before the second application.
  • Follow the manufacturer’s instructions about when it’s safe to re-seed grass. Seed new grass in the area as soon as possible to establish healthy lawn crabgrass can’t break through.
  • If you use a post-emergent herbicide during the summer, care for your lawn according to the lawn maintenance tips above.
  • If the majority of your lawn is crabgrass, it may be best not to remove it during the summer. Wait and renovate the lawn in the fall.

Preventing Crabgrass in the Future

The best defense against crabgrass is a healthy lawn. Unwanted grasses and weeds simply can’t get the necessary toehold to thrive in a robust stand of grass. Follow these basic lawn care guidelines to keep crabgrass from becoming a problem in your yard:

  • Mow at frequent intervals to keep the grass a fairly consistent length. Check the recommended mowing heights for your type of grass and cut your lawn at the highest recommended setting. Crabgrass requires plenty of light to germinate, so keep the grass as thick and long as possible to create shade near the soil surface. Cutting your lawn too close produces patches where crabgrass and other weeds can germinate.
  • Remove no more than one-third of the grass blade at one time when mowing. Removing more not only allows more light to reach weeds, it also can injure the grass.
  • In an established lawn, water in long, heavy intervals rather than shallow, frequent ones. Watering on an irregular schedule and only when needed promotes deeper root growth that’s essential to healthy turf grass. Remember that most established lawns require about one inch of water per week from rain or irrigation. If your lawn is newly-seeded, water in shallow, more frequent intervals until the grass gets established.
  • Fertilize your grass at least once a year, following the package instructions.























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