If you cover the "weeds" after spraying them with Burn Out is a waste of your money since depriving them of access to sunlight will kill them, without any herbicide.

The product should have detailed instructions on the label. If you're willing to wait for smothering, why bother with poison?

It doesn't appear to be poison, but a combination of food grade ingredients. Citric Acid ..... 11.00%
Clove Oil ..... 6.50%
Sodium Lauryl Sulfate ..... 3.00%

Other Ingredients:
Mineral Oil (USP), Lecithin, Water.
Total Other ..... 79.50%

I couldn't tell you how effective, is not something I've used. The label states it will kill annual weeds overnight. Perennial weeds will react as with many things that quickly defoliate rather than act systemically, those will likely return from the roots and a second application minimum will be required as those begin to regrow.

You'd be spraying foliage, not soaking the ground, and the product doesn't appear to me to have many negative effects. It won't be an instant fix though, you'll have to stay consistent with applications. Whether you use the spray, or cover and smother would be your choice.

Just be aware that if you plan to eventually dig, replant, you'll be turning up dormant weed seeds in an area thats been neglected. Applying a good mulch around desireable plants would be helpful there in preventing future germination.

Oh, thanks for clarifying that, Morz! I might consider using something like that. Wonder if it'll kill Nandina? There's a shrub out front I can't dig out because it's too close to gas lines.

Chipster, I apologize for my previous incorrect assumption. I still wouldn't use this or any product for an area that could/would be smothered, though, just because it would be an unnecessary expense (and work.) Have you considered cardboard instead of the weed barrier stuff? Cardboard could be left in place, easier and adds a small bit of organic matter to the soil.

I plan to do this very thing, again, for the umpteenth time this weekend. I asked my honey to save some of the huge pieces of cardboard that come in some kind of stuff they have at his work and we have accumulated enough to start a new bed. We previously tilled, then have let it grow all summer. That will provide a ton of "green" under the cardboard, which is a brown of course. Lay the cardboard, overlapping generously, then cover with tons of compost and then leaves when they fall, and probably will just dump any fine (not large pieces) compostables there until about mid-Jan. By March 1, that area should be ready to start being the home to some awesome veggies, a few shrubs. But this is not a set recipe. People cover the smother layer with many things, in varying amounts, depending on their budget, patience level, available items, soil type, etc...

This is not practical for all situations, mostly depending on which weeds one is battling, their size and tenacity, if there are any that won't flatten, if it's too dry it can take too long for the smother layer to decompose. Feel free to investigate "lasagna gardening" for tons of reading on the subject, and/or you're of course welcome to post pics of the area to solicit further specific ideas/advice.

Just realized I'm assuming (again, so soon!) you want to have a new planting area? If so, would also urge you to start thinking about an edge, so you'll be ready to implement it ASAP. Without some type of barrier to keep the grass out, you'll fight an unnecessary battle and experience unnecessary discouragement. If not, nevermind most of what I said since you probably don't want to do all that just to start a new lawn.

Anything that poisons something, insects, plants, people, has the potential to adversly affect our environment. Because of the amount of poisons we have ben spraying lower life forms, frogs and toads, are showing signs of genetic modification or are dying outright.
Even if this product, which kills plants, is labeled as an "organic" product it may have adverse affects on the environment.

kimmsr, because a solution burns the cuticle of the plant, or in some other way kills it, does not mean it is a poison to other life forms.

If you suspect or know a substance does harm other life forms, please give some persuasive, informative facts. And if you want to discourage use of something, please give a viable alternative. If you can't, why trouble readers with, "maybes?"

Melsor, the manufacturers of a popular plant poison, glyphosates, have told us for years it does not cause harm in the environment and yet numerous studies indicate it does. Since very few people are really doing any research of the harm these products do, even though we know that often when two chemicals mix they can create something much more potent then either chemical by itself, so this whole area is fraught with maybes.
Why, if the consumption of fat has ben cut in half in the last 40 years, are obesity, heart disease, and diabetes still so epidemic? We were told in the 1970's that fat was the cause of these diseases. Why are the children of migrant workers working where the use of Carbaryl is prevalent showing signs of genetic modification that cannot be traced to normal? Why are frogs and toads showing those signs of genetic modificatioon, 5 and 6 legs or 2 or 3 legs, etc. and dying in habitats that are normally safe for them?