These Companion Herbs Can Protect Potato Plants From Pests, Says Our Professional Gardener

Like many vegetable gardeners, I love growing potatoes. They're fairly low-maintenance, don't need too much space, and can be planted strategically for a long harvest season. Placing suitable companion plants beside your potatoes can help them thrive and also improve the garden soil. For example, beans and peas replenish nitrogen absorbed by potatoes in their growth cycle. I also plant various herbs next to potatoes to help protect them from insect pests, including thyme, chives, basil, dill, and a few others.

Many herbs grow well alongside potatoes, especially in smaller urban gardens where space is a challenge; they fit in well due to their shallow roots. The fragrant quality of herbs not only makes them delicious, but the volatile essential oils that give off savory scents also repel various insects that like to feed on potatoes. These same fragrant compounds also attract beneficial pollinators and helpful insect predators that provide even more protection for your potato plants. 

Potatoes are one of those vegetables many gardeners grow so they can use organic methods, as commercial crops are often grown using pesticides. One occasional downside to growing potatoes organically is that they do tend to attract destructive pests, including aphids and various beetles. In addition to scouting the leaves daily for these nuisance insects (including Colorado potato beetles, one of the worst potato pests), planting certain herbs will help deter them.

Basil, a strongly-scented, sun-loving Mediterranean herb you can easily grow in containers, is useful in the vegetable garden for deterring thrips, a pest that feeds on potato leaves. While not as damaging overall as Colorado potato beetles, thrips can reproduce quickly and decimate potato leaves, causing the plant to weaken. Planting basil in containers near potato plants will repel these common pests, and lend a spicy herbal fragrance to the entire garden.

Dill has a uniquely pungent yet pleasant scent that stands out in the herb garden, and also deters insect pests. It attracts pollinators and other beneficial bugs, including ladybugs, lacewings, and hoverflies, all of which eat aphids, a pervasive pest that can damage potato plants and cause a poor crop yield. Dill is biennial, with a tendency to reseed in the garden, so to keep it under control, you should snip off the mature seed heads before they dry and scatter.

One thing I've noticed about some of the herbs that help protect potatoes from pests in the garden is that they're often the same herbs commonly paired with potato dishes, including chives, dill, thyme, and parsley. But we're mainly concerned with their insect-repelling properties at the moment! Whether you grow curly or flat leaf parsley, its clean herby scent will help attract ladybugs and hoverflies that will keep annoying, destructive aphids in check. Why not add both dill and parsley to your herb garden row or containers near your potatoes to help attract these useful insect friends?

The sweet, herby scent of marjoram (often called sweet marjoram) is delightful, and also a helpful pest deterrent. Marjoram is one of a number of fragrant herbs that acts as a "masking plant," meaning its strong scent can fool insects into thinking the plant they seek isn't nearby. It's worthwhile to add this herb to your garden in the vicinity of your potato plants to help keep harmful pests away. Marjoram grows well in containers, or you can add plants alongside your potato rows, where they will form a kind of herbal summer ground cover.

Being an allium, chives are related to onions and garlic, and all of these potent smelling plants deter aphids, a common pest of potatoes. As a bonus, chives also repel Japanese beetles, which sometimes feed on the underground tubers of potato plants. Chives have a pleasing, lemony scent (less pungent than onions and garlic), and produce attractive pale purple flowers. Snipping these flower heads off as they start to fade keeps the herb stalks healthy and stimulates growth. Chives form perennial clumps in the garden and are easily divided in spring.

Though not commonly seen in American gardens, lovage is simple to grow. This aromatic, versatile perennial herb is in the carrot family, with a fennel-like fragrance and a look and flavor similar to celery. The flowering tops of lovage attract parasitic wasps: tiny, non-aggressive wasps that are not interested in stinging humans. These small wasps are great pollinators, and also natural predators of more destructive garden insects such as cutworms and aphids that feed on potatoes.

Flowering catmint is recommended for repelling Colorado potato beetles, a pest that plagues potato growers. This plant (Nepeta) is sometimes confused with catnip (Nepeta cataria), though both are species in the mint family. Catmint's flowers are pale violet blue, while catnip has white flowers. Both plants contain compounds that will repel these beetles (and attract cats!). Flowering catmint comes in a variety of cultivars, many of them smaller than catnip plants, which grow into large mounds up to 3 feet tall, making it slightly less practical as a companion plant in a vegetable garden. 

There are many varieties of thyme to grow in your herb garden, from tiny creeping thymes that can be planted for an aromatic walkway, to a range of culinary thymes with hints of lemon, orange, caraway, mint, and many other fragrances. This versatile, low-maintenance Mediterranean herb isn't fussy about soil but does need lots of sunlight to flourish. Thyme is also one of a number of fragrant flowering herbs that repel mosquitoes and other bugs with its herby perfume, as well as attracting beneficial insects like ladybugs, which help control aphids that feed on potato plants.

Cilantro is a fragrant herb that is easily grown in containers or in-ground garden beds. When allowed to flower, the crowns attract many beneficial insects including hoverflies, ladybugs, lacewings, and parasitic wasps. These helpful insect predators protect potato plants from two voracious pests: aphids and the larvae of Colorado potato beetles. Further, the pungent scent of cilantro also deters Colorado potato beetles in their adult form.