how best to kill a lawn - Ask Extension
I have a relatively small area of grass - about 14 feet by 20 feet. I've had good luck in the past killing small patches of grass using cardboard top...
Knowledgebase
how best to kill a lawn #922561
Asked December 01, 2025, 12:21 PM EST
I have a relatively small area of grass - about 14 feet by 20 feet. I've had good luck in the past killing small patches of grass using cardboard topped with mulch. I know that leaves will kill grass but I haven't heard of using leaves to purposely kill grass - would it work to put a thick layer of leaves topped by mulch to kill it?. I want to create a native habitat in the spring. Would be nice to avoid using cardboard but if that's the best way, I can do that. Thanks.
Multnomah County Oregon
Expert Response
Cardboard isn’t necessary to kill lawn or most weeds, if a deep layer of wood chips is used. WSU Extension Agent Linda Chalker-Scott lists 8-12 inches, and I have personally had success with this. See the full description of using wood chip mulch (often free as arborist chips), in this publication.
You ask specifically about leaves, and I don’t know of any science to share about the depth or type of leaves to use. It makes sense that a slick or solid-packed leaf mass can block the air and water transfer into the soil and smother grass as well as cardboard would, with the benefit of leaves breaking down better than cardboard. Linda writes against using a paper layer in this WSU fact sheet.
So, using the information I’ve found, my recommendation is that leaves under mulch or mixed into mulch, is fine. The main issue killing grass is that the mulch must be deep enough.
Best wishes with your planting.
You ask specifically about leaves, and I don’t know of any science to share about the depth or type of leaves to use. It makes sense that a slick or solid-packed leaf mass can block the air and water transfer into the soil and smother grass as well as cardboard would, with the benefit of leaves breaking down better than cardboard. Linda writes against using a paper layer in this WSU fact sheet.
So, using the information I’ve found, my recommendation is that leaves under mulch or mixed into mulch, is fine. The main issue killing grass is that the mulch must be deep enough.
Best wishes with your planting.
Thank you so much! I'd much rather use an organic method like leaves than cardboard. I think I'll get a load of cedar chips rather than chip drop just because they can be so variable.
Again, I appreciate you taking the time to answer - heaven knows there are enough leaves around to accomplish this!
Janis
On Monday, December 1, 2025 at 05:15:23 PM PST, Ask Extension wrote:
Great! If you’re willing to share a photo of what you did, and how it worked come springtime, I’m interested.
This is the "before" picture. Will update as the project progresses.
