Arlene Hamilton

Master Gardeners

If your family includes cats, dogs or other backyard pets, you can keep them healthy and insect free using some common herbs. Herbs are multi-talented members of the plant world. Aside from being the source of both natural and synthesized medicines, they spice up our food and supply us with an array of sweet-smelling perfumes and potpourris. 

Another use of these wonderful plants is their ability to safely control unwanted insects. Unlike synthetic chemicals, whose ingredients and quantities must be continually revised and increased in response to insects’ immunities to them, pests don’t become tolerant of botanical repellents.

Many herbs emit powerful aromatic and volatile oils, which may appeal to humans, but are disliked by many insects. Because of their acute sense of smell these aromas are unpleasant to insects. These pests will abandon areas where such herbs in fresh, dried, powdered, or essential oil forms are used. These same herbs are often tolerated, if not enjoyed, by pets.

The strongest herbal repellents against pests such as fleas, lice, ticks, chiggers, mosquitoes, and gnats include Citronella, Eucalyptus, Pennyroyal, Rosemary, Southernwood, and Wormwood. Milder ones include Basil, Bay, Lavender, Sage, and Thyme.

Citronella - Although there are many lemon aroma plants in garden centers and nurseries labeled as citronella, the one thought to be the most effective as a mosquito control is Lemon grass - (Cymbopogon citratus).  Lemon grass grows well in North Texas, and will winter over down to 10 degrees with heavy mulch. It grows best in full sun, good drainage, and requires little water after established. Plant around sitting areas or harvest the long grass stems, chop into pieces and strew in areas where pets and people like to rest. Exercise caution when handling, as the long blades of grass are sharp and can cause cuts.

Pennyroyal - (Mentha pulegium) is used to repel mice and insects such as fleas. Traditionally, pennyroyal was planted around doorways, used in bedding, and as a strewing herb. Its oil is used commercially in soaps and detergents. A strong infusion of its leaves can be used as an insect spray. Pour two cups of hot water over one cup chopped leaves, let steep for 30 minutes, strain and use as a rinse on your pet. Pennyroyal needs moist, semi-shady conditions for best growth in the South. Note: Pennyroyal leaves should NOT be ingested by pets or people.

Rosemary - (Rosmarinus officinalis) leaves, along with Lavender flowers, make an excellent, soothing, healing, and pest-repellent conditioning rinse for pets. With four cups of hot water, steep one cup fresh, chopped herbs. Steep in a covered container for at least one hour. Cool and strain. Use within one or two days. This tea can also be poured into a spray container and used as a room freshener. Rosemary leaves are gentle enough that fresh leaves can be rubbed directly on pet’s skin to provide temporary insect-repelling relief. Rosemary thrives in the North Texas sun and soil. Give it lots of room in the landscape, as it will grow to four feet or more.

Southernwood (Artemisia abrotanum) and Wormwood - (A. absinthium) have been used since antiquity to repel insects. Many gardeners find that Artemisias, extremely aromatic herbs, inhibit the growth of neighboring plants. However, set around fences or perimeters of gardens, they can be useful to repel slugs, snails, rodents, and certain small animals. They are also a repellent to garden and cloth moths.

Look for more info about using herbs for healthy pets in next week’s column.

Arlene Hamilton is an Ellis County Master Gardener and guest columnist in the Daily Light. For further information, contact the Ellis County Master Gardeners at the Texas AgriLife Extension Service, 701 South Interstate 35E, Suite 3, Waxahachie, or call 972-825-5175 or e-mail: