Vinegar Update

This all-natural weed treatment is not without some problems, though. One thing to remember about vinegar is that it's non-selective, meaning that it destroys anything green, whether weeds or a prized plant. Take extra care when using it, and avoid vinegar treatments altogether on windy days.

Another problem is that regular store-bought vinegar, which contains only 5 percent vinegar or acetic acid, isn't strong enough to deal with persistent problem weeds. However, you can now buy vinegar that is especially developed for use as an herbicide, and it contains 20 percent acetic acid, four times stronger than the kitchen variety. Garden vinegar does a much better job of eliminating tough, nasty weeds.

Also, too much vinegar can have an adverse affect on the soil's pH level. "After all, vinegar is pretty acidic," explains James, "so I suggest you use it only to spot treat weedy areas in flower beds rather than in or on the lawn, and don't over-do it when spraying." Treating a large area of lawn soaks the soil with too much vinegar, resulting in an overall decrease of the pH level. "Actually, some people do douse the soil with this stuff to lower the pH to the point where few if any plants will grow," says James, "but I don’t recommend it for that use because it renders the soil inhospitable to plants for at least six months."

Caution: Never use the garden-variety (20 percent acetic acid) vinegar for cooking!

Citrus herbicides

Herbicides made from various citrus oils and from oils of cloves and cinnamon work every bit as well as concentrated vinegar, and they smell a whole lot better, too. "Actually, I know of at least one product that combines citrus oils and concentrated vinegar for that one-two punch," James says. "But again, although that may sound like the basis for a tasty vinaigrette, these products should never be used for cooking or eating. "

Although vinegar and citrus herbicides contain all-natural ingredients, that doesn't mean that they don't pose a threat to humans and other critters. "Try to avoid using them when the bees are buzzing and other beneficial bugs are active, and avoid using them near ponds that contain fish, or near edible food crops," says James. Also, remember to wash your hands thoroughly after using any garden chemical whether natural or synthetic, and consider wearing gloves while spraying.