Kill the Weeds But Spare the Dog

The crabgrass and dandelions just won’t quit, marring an otherwise lovely lawn. You’d like to use weed killer but hesitate because you’ve heard — and observed on lawn sign warnings — that the pesticides and herbicides applied to grass are not safe for dogs.

For traditional commercial weed killers, it’s often true. Some products have caused symptoms ranging from vomiting to lethargy and even convulsions, according to the National Pesticide Information Center. Others have brought about serious respiratory distress. And then there’s the potential cancer risk. For instance, in a study involving 160 Scottish terriers, researchers at the Purdue University College of Veterinary Medicine found that those dogs exposed to lawns or gardens that had been treated with herbicides and pesticides were seven times more likely than unexposed dogs to develop a form of bladder cancer known as transitional cell carcinoma. The researchers say that any breed at high risk for this type of cancer should be “restricted from lawns treated with herbicides and pesticides.” It’s a longish breed list that includes not only Scottish terriers but also Shetland sheepdogs, Airedale terriers, beagles, West Highland white terriers, and wire-haired fox terriers. But no dog is immune from that disease.

So what do you do? Take heart. You can have your dog and weedless lawn, too, by applying products with ingredients that are safe for your canine pal.

Four weed-killing ingredients that you also cook with

The four substances listed here will all kill weeds without harming your dog. You can use them straight from your kitchen or, in most cases, buy products in which one or more of these substances are the main ingredients. Keep in mind that all of these items are non-selective, meaning they’ll kill lawn grass, too. You want to apply them just to weeds themselves.

Boiling water. Because it’s hard to control where boiling water goes as you pour it out of the pot, you’ll want to use it on weeds that are not surrounded by grass, for instance, in cracks in your driveway, flower beds, or vegetable gardens. (Boiling water will not harm the soil.)

Vinegar. A kitchen ingredient, yes, but truth be told, you need a vinegar concentration stronger than what you’re going to put in your salad dressing, which is only about 5 percent. A solution that’s more on the order of 10 to 30 percent vinegar is what’s necessary to finish off the weeds. You can spritz it from a spray bottle.

Another option: buy a commercial vinegar-based weed killer, which shouldn’t be much more expensive than high-concentrate vinegar. A couple that fit the bill are Green Gobbler Ultimate Vinegar Home & Garden and Natural Armor Weed & Grass Killer.

Salt. Salt makes it difficult for plants to grow in soil. Dissolve it in water (two to three parts water to one part salt), and spray away — again, only on the weeds you want killed, not on the lawn itself.

Dr. Kirchner Natural Weed Killer contains salt — as well as vinegar and soap, which helps the mixture stick to the plants you want dead.

Sugar and chili powder. It might sound like a recipe for a mahi-mahi rub, but the sugar renders the soil inhospitable for plant growth (so use it only where there are weeds and no grass), and the chili powder will keep away ants and other insects that would otherwise be interested in the sugar. Sprinkle the mixture directly onto the weeds.

Making sure weeds never have a chance

Along with killing weeds that have already popped up, you can help insure that weeds don’t grow in the first place by applying a safe “pre-emergent” that keeps seeds from germinating. One effective substance is cornmeal. That’s the active ingredient in Preen. It’s more expensive than a number of other weed killers — a 14-pound container of Preen Extended Control Weed Preventer retails for almost $44 on Amazon. But it does the trick. If you use it on vegetable gardens as well as lawns and flower beds, it’s even safe to use up until the day of harvest.