Smothering effectively kills weeds in areas earmarked for future planting. After mowing or cutting off the top growth, lay down a mulch of heavy cardboard, newspaper (in a layer at least three dozen sheets thick), or black plastic. Overlap these materials so weeds can't grow through the cracks.
Leave the plastic in place for however long it takes to kill the grass and weeds underneath. In the summer it may only take two to three months, in the winter it can take double that. If you have a lot of tough weeds underneath, it may take up to a year.
If you're thinking about using landscape fabric over existing weeds and grass to smother it, this is not recommended. The area you want to cover should be stripped of all vegetation first to avoid tough weeds from poking through the material.
Yes, mulch can do the trick, but most people don't put it on thick enough and the professionals can use less mulch if they add landscape fabric on top of the soil. The fabric suppresses the weeds for a couple of years, but eventually, new weed seeds blow into the landscape bed.
Whether your raised garden bed ideas require a new form of weed control or you're battling weeds on your lawn, the cardboard will come in handy. 'It is thick enough to smother weeds, but unlike landscape fabric, it'll rot over time,' John says.
HOW LONG DOES IT LAST? This process is a temporary solution, not a permanent fix. The big advantage to cardboard is that it doesn't stay there forever, getting locked up in soil layers. I've seen the cardboard disintegrate after 6 months.
Plastic Sheeting: A thin, black plastic that's used to smother weeds and retain soil moisture. It's affordable and practical to use to kill weeds compared to herbicides. But since the material is thin, it will break down after a few weeks, especially in harsh climates.
Clear plastic tarps from your local hardware store (2-6 mil) are sufficient for solarization. In dry climates, the process typically takes around two to three weeks during hot summer months. The process is complete when the vegetation underneath the tarp is dead.
Tarps can be applied to fully-prepared soil (lightly tilled, amendments added, residue incorporated, etc.), or laid directly over a mowed cover crop or weeds, and can be left in place for any length of time, though most beneficial effects need at least three weeks.
To kill weeds, some amateur gardeners recommend combining Epsom salt and Dawn dish soap. Together, these household items create a potent mixture, so only use it in places you wish to eliminate weeds, such as a patio or sidewalk permanently.
"The acid within vinegar breaks down cell walls and removes moisture from weeds, causing them to die off," she says. "Vinegars that you keep in your kitchen, such as white vinegar, contain a level of acidity that can help remove weeds without affecting surrounding plants."
The researchers found that 5- and 10-percent concentrations killed the weeds during their first two weeks of life. Older plants required higher concentrations of vinegar to kill them. At the higher concentrations, vinegar had an 85- to 100-percent kill rate at all growth stages.
Will roots grow through cardboard? Yes! Unlike silage tarps, cardboard decomposes into the soil making it the perfect element to use in the no-till method.
Cardboard and Paper Concerns
The glue used in cardboard boxes can contain chemicals, but the glue used to form the cardboard itself is derived from starches found in plants like rice, wheat, potatoes, and other tubers. This is perfectly safe to use in your garden and will eventually decompose.
The paper material used is typically newspaper (up to eight layers thick) or untreated cardboard. Because a blanket of this decomposable material blocks sunlight and forms a physical barrier, it is more effective than organic mulch alone at smothering existing weeds and suppressing the growth of new weeds.
The Cons – Using Cardboard In The Garden
Add to that, many cardboard products also contain man-made ink compounds that can also soak into the soil as well. Some even contain small amounts of plastic that won't decompose.
Though termites can eat some types of wood, they prefer cardboard in taste testing. If they are given no choice and have only wood to eat, they will consume it but their survival rate decreases.
One of the major drawbacks cited about landscape fabric is that it prevents nutrients from reaching the soil, which can cause it to become unhealthy in turn. Yet, Kemper says Jobe's fabrics allow the air, water and nutrients still reach the plants while keeping weed seeds from germinating.
You're dealing with compacted soil: Compacted soil is when the soil is too tightly packed together, preventing air and water from reaching the grass's roots. The grass then dies, leaving bare dirt patches perfect for weeds to take root. To fix this problem, you'll need to aerate your lawn.
Herbicides. Herbicides are used in many ornamental production areas as an economical option to control weeds. By using herbicides before weeds emerge, weed competition with the ornamental crop can be reduced or eliminated, resulting in higher quality ornamental plants and less labor costs.