Certain weed killers pose more of a danger to your shrubs and trees than others. Some to avoid are: Glyphosate: The main active ingredient in Roundup and similar products. Roundup will damage or kill trees and shrubs if sprayed on leaves, bark, or branches.

Can I spray weed killer under hedges?

Falcon is selective weedkiller for the control of grass weeds around hedges. It has a contact action so will kill any grass it touches. It is very safe around the base of trees and hedges and can also be sprayed over the top of the hedge if needed. ... It is particularly safe to use in the bottoms of hedges.

What herbicide kills hedges?

Spray foliage with an herbicide with an active ingredient, such as glyphosate, triclopyr, dicamba or 2,4-D. Apply the herbicide during August and September, according to the Washington State University Extension. Always dilute sprays to ensure they move into the plant's system.