Several organic methods, both homemade and store-bought, work well to control outdoor fleas. Flea control in the yard can be as targeted as spot-treating your dog's favorite napping spot under the old oak tree--or as extensive as dusting a large lawn. Start by treating the most problematic areas, which may completely solve the problem. Combine outdoor flea-control methods with indoor practices like using organic pet shampoo and household cleaners geared to natural pest control.
Home-Grown Herbal Control
Your garden can provide many herbal flea treatments. For the simplest method, sprinkle fresh or dried leaves in the most flea-ridden areas of your yard. It may take experimentation to determine which botanicals work best in for your specific yard conditions. Fleas thrive in shady spots. Sprinkle whole, crumbled or powdered herbs under bushes, in dark corners, and other places you may have noticed where fleas are prevalent.
For treating larger areas, boil a pint of water and pour over a handful of fresh herbs, or 2 to 3 tablespoons dried herbs. Steep for 30 minutes, strain, and pour into a plant mister when the liquid is cool enough to handle. Spray the infused herbal liquid throughout the yard.
According to herbalist Barbara Griggs, many of the "strewing herbs" once used to deter indoor pests work equally well outdoors. Perhaps the most well-known flea control herb, pennyroyal, gained its botanical name, Mentha pulegium (flea mint) from its reputation for deterring the tiny pests. Pennyroyal grows in sun or shade and prefers moist soil. Southernwood and wormwood, both silver-leaved artemisias, contain pungent oils renowned for deterring fleas and moths. Grow them in a sunny spot in the herb garden, and provide them with soil on the sandy, dry side.
Other pungently-scented herbs worth trying are fleabane and feverfew, both daisy-like flowers which prefer sunny conditions, and the sun-loving Mediterranean herbs--sage, lavender and rosemary.
If you lack the growing space for an herb garden, consider buying essential oil versions of any of the botanicals mentioned above. Put a few drops of the oil in a planter mister filled with water and spray where needed.
Many organic garden centers and mail order nurseries offer microscopic worms called nematodes, which consume a several kinds insects, including flea larvae. The Texas Agricultural Extension Service warns that nematodes' exact level of effectiveness against outdoor fleas has yet to be determined.
The service does cite studies that show nematodes to better control fleas in yards with sandy soils than in those with normal-to-clay soils. The service also suggests that, along with following package directions, homeowners irrigate their lawns before and after nematode application. This practice prolongs the lives of the nematodes and makes them more aggressive hunters of flea larvae.
Mother Earth News recommends diatomaceous earth for outdoor flea control. The organic product, processed from the shells of tiny sea creatures, shreds the tender exoskeletons of fleas, slugs and other insects. These exterior rips ultimately cause dehydration and death. Make sure to buy garden-grade diatomaceous earth (several varieties are sold), and sprinkle it in shady areas and on grass. Apply once a week, and after each rainfall.
While diatomaceous earth is a completely natural product, be sure to wear a dust mask or scarf when applying it. The powdery substance can irritate lungs if ingested. Also take its universally-damaging properties seriously. Apply the product sparingly to areas in which you hope to encourage "good" insects and reptiles to avoid unwittingly killing them in the process of deterring fleas.