how to get read of crab grass
Crabgrass (its botanical name is Digitaria sanguinalis and Digitaria ischaemum) is an invasive species that is native to Europe but is now found all over the world. Its leaf blades are 5–15 cm long and 3–12 mm wide and range from green to purple in colour. If you let the plant grow, it produces 4–10 flower spikes each 2-16 cm long. Crabgrass grows in many different habitats from urban gardens to natural forests and wetlands and in all kinds of soils, even in shallow soil. It is highly adaptive to different environments.
An annual, late spring-and summer-germinating plant, a single crabgrass plant can bear more than 150,000 seeds! Its seed can be carried in soil, sand, and gravel over long distances. Seed germination is related to soil temperature. When the soil temperature at the surface reaches 13°C for four or five consecutive days, crabgrass begins to germinate. Early spring to late summer temperatures are perfect for the germination of crabgrass seeds. The earlier they germinate in the season, the larger and more competitive they are. A warm season grass, they become established in the lawn just when our cool season lawn grasses are dying from heat stress.
To control crabgrass in your lawn, the best practice is prevention by maintaining a healthy lawn. Crabgrass growth is encouraged by poor lawn management. Establishing a dense and healthy stand of turfgrass is the best way to control crabgrass and other annual weeds including grasses and broadleaf weeds.
The proper mowing height and frequency, fertilization and irrigation are part of a sound weed control program and should be practiced throughout the growing season. Depending on the kind of grass you have, the ideal mowing height is between 2 and 3 inches (6–8 cm). Taller grass creates shade and decreases the germination of crabgrass. Proper lawn watering will also help control crabgrass. When lawns are watered just on the surface, it promotes the germination of crabgrass. Watering should be an “all or nothing” type of commitment. If you water, do it consistently and deeply. If you cannot water consistently, it’s better not to water at all and to allow the grass to go dormant until natural conditions bring it back. Encouraging deep root growth by irrigating infrequently, but heavily, will maximize water-use efficiency and turfgrass quality. If you want to seed a new lawn, late summer is a good time since as an annual plan, crabgrass seed will be killed by early frosts. A thick turf in the spring will compete better with weeds like crabgrass.
Crabgrass can be pulled, but do this before they set seed, that is before a flower emerges. Herbicides and pesticides are prohibited in many municipalities, and Toronto is no exception. Crabgrass cannot be controlled in one growing season because of the great number of viable seeds that accumulate in the soil from years of infestation. Satisfactory control may require several seasons of conscientious adherence to a good management program.
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