The "Cardboard Lasagna" method of turf suppression builds top soil, suppresses many plants, including turf species, does not disturb tree roots, and does not have to be removed later.

It simply deteriorates on top of the grass. Add compost or a mix of compost and mulch, and you can seed directly into the new soil.

• Collect cardboard, preferably not plasticized.
• Remove tape from cardboard.
• Lay cardboard on top of turf. If you do not have enough cardboard, you can use @7 sheets of newspaper instead of cardboard. Be sure there are no gaps, or whever is under the cardboard will find a way through.

• Add 3-4” of compost or a mix of compost and mulch on top.  Do not use food scraps, or squirrels will be digging up your cardboard.  

• You can sow seeds directly into the compost and mulch.
• Keep it moist to help the cardboard deteriorate more quickly and for the seeds to germinate.
• It is possible to add plugs (e.g., coneflowers) right on top, splaying the plug roots to fit them into the 3-4” of compost and mulch. That worked well.
• For the project pictured, 3 cu yards of mulch and compost (about 1.5 cu yards of each) covered the front parkway area.

Some turf grass found its way around edges of cardboard. Also because there was an existing tree and native plantings to preserve, there were some gaps where Creeping Charlie and mile-a-minute vine continued to be a problem.

Alternatives:

• Removing the turf, which removes the topsoil and to my mind is a lot more work, plus you have to dispose of the turf.
• Solarizing with sheets of clear plastic.  You have to get a lot of plastic and then later, remove,  keep and/or dispose of it.
• Herbicide, which kills the soil microorganisms and fungi that you are wanting to encourage.