What to do about Crabgrass – Yates Custom Lawn Sprinklers

Having been involved in lawn care since the early 1980’s, I do have experience in dealing with crabgrass. Unfortunately, there aren’t any easy solutions, or silver bullets for eliminating or preventing crabgrass. Since the introduction of the Cosmetic Pesticide ban in 2008, there have been no selective treatments available for his pernicious plant in Ontario.

The only product that can be used to prevent crabgrass in Ontario is Corn Gluten. This usually is applied as a granular product, requiring high volumes (>4.5 KG per 100m²) to be effective. Applied in the spring, it will prevent annual weed seeds from germinating. Be aware that it does take several years of use to build up enough gluten in the soil to reduce crabgrass populations. It is important NOT to disturb the soil in any way after applying.

In the meantime, to reduce current and future populations the best options remain cultural controls:

Plan ahead to deal with crabgrass for the coming season. Avoid mechanical disturbance of the soil in early spring unless you are planning to heavily overseed immediately afterwards. It is a best practice to overseed a lawn at least twice a year, to maintain thickness. A thick, healthy lawn is your best defence against crabgrass.
Maintain a minimum 3” mowing height. This is particularly critical in areas that are mechanically trimmed, not mowed. Curbs and edges are the most susceptible to crabgrass, so this should be discussed with your lawn care contractor should you be using one. If you are comfortable with mowing every 3 to 5 days, then mowing heights of 4” can have significant impacts on reducing crabgrass germination.
Maintain regular irrigation. If any section of the lawn is allowed to dry out and wilt, crabgrass will quickly overwhelm the existing turf and thrive.
If crabgrass is already an issue: On small areas (curbs, edges, sections <10m2 hand pulling is the best option, as crabgrass does not regenerate from its roots. In a larger area (>100m2), then the best practice may be to wait until late summer (mid-August to mid-September) to renovate the area with topsoil and seed or using a slit seeder (preferred method). Alternatively, resodding the larger area will work if that’s within your budget

In summary, a lawn care plan involving the above product and cultural practices will work for managing crabgrass, but patience and care remains tantamount to success.

Feel free to contact me directly if you have any other questions

Charlie Cameron, charlie.cameron@yatessprinklers.com