Lawn Treatments for Crabgrass & Dandelions

The appearance of weeds easily mars the appearance of your otherwise thriving lawn. In some cases, the weeds may actually steal crucial nutrients and water away from the grass' roots, which can lead to a lawn with unsightly yellowish spots. Lawn treatments for crabgrass and dandelions---two very common lawn weeds---help you eradicate or at least control these plagues and maintain the grass' health aboveground and below.


Crabgrass and dandelions fall into different classes. Crabgrass is recognized as being an annual weedy grass, while dandelions are referred to as perennial broadleaf weeds. When crabgrass dies off in winter, it leaves unsightly bare circles in the lawn; they provide germinating grounds for next year's crabgrass.

Herbicide Application

Treat dandelions with a post emergence herbicide that the plants absorb via their leaves. This requires you to wait with treating the lawn until you see these weeds growing. The more leaves the plant has, the more effective the herbicide will be. Apply liquid broadleaf herbicides preferably in spring, when temperatures fall between 60 and 80 degrees Fahrenheit. Avoid watering the lawn for about 48 hours after application. Prevent the growth of crabgrass with a pre-emergence herbicide during early or mid spring, when the temperature of the soil fluctuates between 55 and 65 degrees Fahrenheit. For the state of Colorado, this might occur during the latter part of March, while in Minnesota this likely occurs in the beginning to middle of May. The substance kills the germinating crabgrass seeds belowground and therefore prevents the actual aboveground appearance of the weed grasses. This kind of herbicide is usually available as a granule formula that you can distribute with a hand spreader.

Mechanical Treatment

You can better your lawn's odds of successfully competing against invading crabgrass or dandelions by mowing the grass at an appropriate height. Allowing three inches of grass to remain after cutting leaves behind more surface area for photosynthesis to occur; this results in healthier grass with stronger roots and can also provide too much shade for weeds to adequately germinate and grow.


Crabgrass germinates primarily from the middle of spring to the middle of summer. Warming soil and frequent light watering sessions present excellent conditions for the grass to grow alongside the desired lawn grass. Cut back on watering in accordance with your lawn grass' needs and opt for infrequent but deeper water applications, which nourish the already existing roots of the lawn but fail to provide frequent applications of surface soil moisture.

Eco-Friendly Lawn Treatment

The Northwest Coalition for Alternatives to Pesticides advises that homeowners may use corn gluten meal to weaken crabgrass and dandelion seedlings to such an extent that a healthy lawn can compete against the majority of these invading plants. The substance decreases new plants' root growth but does not endanger the root health of the already established lawn grass. An estimated application would require you to spread 20 pounds of the corn gluten meal for every 1,000 square feet of lawn you want to treat.

Keywords: crabgrass, dandelions, grass

About this Author

Based in the Los Angeles area, Sylvia Cochran is a seasoned freelance writer focusing on home and garden, travel and parenting articles. Her work has appeared in "Families Online Magazine" and assorted print and Internet publications.