PlantLife Online

Answer

Controlling or eradicating quack grass in lilies or any other perennials can be very difficult without killing or damaging the perennials. Quack grass grows and spreads by rhizomes which are underground stems with nodes every inch or so that are capable of producing new shoots. Pulling the shoots or using a rototillers to control the quack grass will only amount to more shoots sprouting from the dormant node.

The best method to control quack grass is by using a herbicide that contains glyphosate (Monsanto Roundup). Herbicides with glyphosate are non-selective and will kill all plants they come in contact with so it is important to be careful when treating perennial gardens. Since overspray will damage your lilies the best way to apply the herbicide is to use a sponge or small paint brush applying the liquid herbicide to actively growing green leaves. More than likely it will take more than one application to completely eradicate quack grass from your garden. Using a selective systemic herbicide containing fusilade found in (Ortho-Grass-B-Gon) can also be used successfully. Just like round-up avoid contact with other plants especially lilies, day-lilies and iris, a paint brush or sponge are the best mode of application.

Avoid composting quack grass, seeds may stay viable for up to 5 years.