Q: Our lawn is infested with weeds. I’m planning on killing it all and starting with new grass seed, but I’m wary of the chemicals in the liquid herbicides. What are some natural ways to kill the old weeds?
A: To kill the old lawn without chemicals generally requires disturbing the topsoil and destroying the root system. This can be done with a gas-powered tiller, tilling the area 4 to 8 inches deep, raking away the grass and seed, and tilling again. You can also rent a sod cutter, which cuts the turf just below the soil level, or use a tractor and a pull-behind plow. For very large areas, you could enlist the service of a bulldozer, or even rent a skid-steer loader (like a Bobcat), which can be equipped with a bulldozer blade attachment. Finally, for small areas you can use black plastic sheeting to smother the grass. Use enough heavy-gauge plastic to cover the area in question and stake or weigh down the perimeter. This method will kill the grass and weeds by depriving them of sunlight, but it won’t kill weed seeds. The plastic method is also unattractive, and it could take a couple of months to work. In the meantime, you can disguise the plastic with mulch or tree bark if you don’t mind the additional expense.