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Will grass & weed killer kill my trees and shrubs?

Updated June 26, 2017

The outside of your home, including your yard and landscape, is the first thing visitors many visitors notice. Proper lawn and yard care includes the removal of aggressive grasses and weeds. Unfortunately, some types of chemical herbicides can damage and destroy desirable plants, shrubs and trees. Killing weeds while protecting plants requires proper herbicide application.

Weeds

While local governments may determine the classification of noxious weeds, most weeds are simply unwanted plants that grow in maintained locations. Aggressive grasses may perform nicely as lawn covers, but in flowerbeds and gardens, these grasses become weeds. Many types of unwanted plants are broadleaved weeds. Some herbicides kill just the grass or specific types of weeds, while others kill all the vegetation in an area, including shrubs and trees.

Herbicides

Herbicides come in a variety of formulas. Pre-emergent herbicides kill plants as they germinate, while post-emergent herbicides kill growing plants. Selective herbicides only kill specific weeds and grasses, such as brome grass, Canadian thistle and quackgrass. Non-selective herbicides kill a large variety of plants and can have a detrimental effect on trees and shrubs.

Considerations

Beyond mechanical weed removal methods, selective herbicides are usually the safest method of removing unwanted grass and weeds around shrubs and trees. Applying a granular fertiliser will supply a steady stream of herbicide into the soil as the materials gradually dissolve. Stubborn, large weeds may require a direct application of non-selective herbicide to halt their growth. Hand-held sprayers allow you to focus the herbicide directly onto the weedy growth, minimising damage to surrounding plants.

Precautions

Chemical herbicides contain strong ingredients that not only kill weeds, but may also harm your health. Choosing non-chemical methods of weed control, such as pulling or digging the weeds from the soil and planting thick ground covers to deter weed infestation, are generally safer for the environment and the surrounding plants. When using selective herbicides, check the label to determine which plants they kill and which ones they won't harm. Choose ones formulated for use around your varieties of shrubs and trees. Apply these when the weeds and grasses are actively growing and when the temperature is between 15.6 and 26.7 degrees Celsius. Choose calm, dry days to apply both selective and non-selective herbicides. When spraying the weeds with a non-selective herbicide, keep the stream of solution on the weed's foliage. Avoid saturating the soil or spraying beyond the individual weeds.

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About the Author

Piper Li, a professional freelance writer, began writing in 1989. Her articles appear online at Biz Mojo, Walden University and various other websites. She is the co-editor for "Kansas Women: Focus on Health." With a bachelor's degree in journalism from Mesa State, Li enjoys writing about health, horticulture and business management.