Lush planters of flowers and potted herbs increase the ambiance of patios and porches, but they can serve another important function: repelling pests. Scott Farrington, owner of Indian Creek Nursery on the border of the Dundee and Midtown neighborhoods, said controlling pests with plants rather than chemicals is quite effective. (It’s also important to the mission of his nursery, which has cut down on chemical control by 90% in the past five years using alternative methods.) Homeowners who wish to reduce their dependence on commercial chemical products can use many common, attractive, and otherwise useful herbs and flowers to repel pests effectively, he said.

Look to some of the best-smelling kitchen herbs for help keeping the bugs away. Culinary herbs with fragrant essential oils often have pest-repelling properties, Farrington said. Lemongrass is not only a fine culinary herb and an attractive spiky plant, but also repels many pests, especially mosquitoes. Most herb gardens host basil for cooking, but the aromatic annual also helps repels ants, mosquitoes, and flies. Rosemary, another culinary staple, repels mosquitoes and spiders. Common herb fare, such as chives, oregano, and dill, do their fair share of repelling bugs. Blooming chives will attract bees and butterflies (in contrast to repelling unwanted insects). And all of these herbs are well-suited for planting in pots on patios, porches, and other outdoor living spaces, he added. 

Herbs aren’t the only plants with pest-repelling properties. Many flowers have them as well, though some may not be table fare; rather, they’re better suited for ground planting, Farrington said. One such plant, citronella geranium, repels mosquitoes. Chrysanthemum, a frilly perennial flower, repels Japanese beetles and spider mites with its unique scent. Nasturtium repels white flies, aphids, squash bugs, and beetles, he said. It is often planted around the perimeter of vegetable gardens for its repellent properties. 

Farrington said folklore points to the protective power of marigolds. The tales may have some merit, he believes, although he can’t verify. (The blaze orange flowers are particularly attractive though.) And lavender, with its beautiful purple flowers and relaxing scent, repels mosquitoes, ants, and even fleas. Lastly, there’s catnip. It’s not only adored by cats, but also attractive, smells fresh, and its essential oil is a roach repellent (supposedly more effective than DEET), he added.

There is limited scientific evidence in the area of naturally repellent plants; however, some is beginning to emerge. For instance, in a 2016 study by Baidoo and Mochiah, botanical insecticides (specifically garlic and hot pepper) protected nearby cabbage plants from pests and were a cost-effective alternative to typical insecticides (see “Comparing the Effectiveness of Garlic [Allium sativum L.] and Hot Pepper [Capsicum frutescens L.] in the Management of the Major Pests of Cabbage Brassica oleracea [L.],” Sustainable Agriculture Research; Vol. 5, No. 2; 2016). 

Farrington said that many herbs can be made into natural repellent “potions” by boiling leaves and stems, or otherwise extracting the essential oils. These natural concoctions are more environmentally friendly and generally safer than store-bought pesticides, he believes. Indian Creek sells a natural pest repellent made of herbal essential oils including rosemary. Natural concoctions are generally safe for human skin, Farrington said, but should be tested by individual users, as some may have more sensitivity. Homemade concoctions should also be spot-tested on fabric items, such as cushions and patio furniture, as they may stain. 

Planting herbs around the porch provides more than greenery and pleasant aromas. It can facilitate a comfortable, pest-free experience outdoors. Add to your patio a few pots of colorful geraniums, lavender, and marigolds, and you’re likely to lengthen your time outside on those summer days just a bit more. Enjoy!