What Garden Companion Plants Control Insect Pests?

“What’s the best flower to control unwanted bugs in your veggie garden?” Question from Sylvia of Belle Plaine, Minnesota

Answer: Some commonly recommended companion plantings are ineffective, while others are supported by research. Most of the research surrounds vegetable crops and companion plants that reduce the number of insect pests that attack these crops. Companions fall under two categories:

  1. Trap crops: These plantings attract insect pests, luring them away from favorite vegetables. They take up a lot of space and are not practical for most home gardeners, so I will just cover repellent companion plants that have been shown to really help ward off vegetable pests.
  2. Insect-repelling companion plants: These plants ward off certain insect pests in the garden.


These plants emit chemicals that deter insects. Repelling plants will never totally protect vegetables from the pests that attack them, but they can reduce pest numbers. Here are a few good examples of vegetable pests and the companion plants that repel them.

Herbal Insect Repelling Companion Plants

Herbs have been shown to offer repellent protection to specific veggies. Here are the best.

  • Basil (Ocimum basilicum) can reduce the number of tomato hornworms on tomatoes and thrips on flowers. Choose large varieties.
  • Chives (Allium schoenoprasum) and onion relatives repel plant-damaging moths, aphids, and mites that attack a wide host of vegetable plants, such as brassicas (collards, cabbage, broccoli, and cauliflower), beans, and squash, so a border of chives might be really helpful in the garden.
  • Sage (Salvia officinalis), rosemary (Rosmarinus officinalis), hyssop (Hyssop officinalis), thyme (Thymus vulgaris), dill (Anethum graveolens), and chamomile (Chamaemelum nobile) are more edible herbs that may also provide brassicas some protection against common pests.
  • Catnip (Nepeta cataria), wormwood (Artemisia absinthium), southernwood (Artemisia abrotanum), and tansy (Tanacetum vulgare) are inedible herbs that reduce damage by flea beetles, a pest that attacks eggplant, brassicas, tomatoes, and other common crops. One downside is to these repellent plants is that they tend to spread and become weedy. Of these, I recommend catnip the most. Just clip it back occasionally to keep it from flowering and setting seed.

Flowering Insect Repelling Companion Plants

A few common garden flowers also have repelling qualities.

All of the companion herbs and flowers mentioned will flourish in soil amended with fertilizer-enriched Black Gold Garden Soil. I hope that some of these tips. When planting to protect, it is most helpful to plant a close row or ring of repelling plants near the vegetables that you want to protect.

Happy gardening!

Jessie Keith

Black Gold Horticulturist

What are Some Good Companion Plants for Strawberries?

“Are there any companion plants to help strawberries grow and produce better? Or to keep bugs away from them?” Question from Amber of West Plains, Missouri

Answer: The true effectiveness of companion plants to ward off pests is argued. That’s because insect pests can detect their host plants from great distances, and/or they overwinter near host plants from year to year. So, if your strawberries are not covered with a deterring companion plant, there is a good chance they will not be protected. Either way, there are some strong-smelling plants that may be helpful, while also bringing herbal and floral benefits to your strawberry patch and garden. Just be sure that you don’t plant tall plants too close to your strawberries. You do not want them competing for sunlight! And, don’t forget to amend your beds with Black Gold Garden Compost Blend, which is OMRI Listed for organic gardening.

Marigolds: Plant small French marigold varieties around your strawberries–the prettier the better.

Basil: I like mini bush basil. Plant them alongside your strawberries and harvest as needed. The two even taste great together.

Rosemary: Shorter or trailing rosemaries may also provide some benefit.

Sage: The strong leaves of sage ward off certain insects and may benefit your strawberries.

Thyme: Most any thyme variety would be the perfect complement to your strawberries. I would recommend lemon thyme, which is believed to deter more insect pests.

I also suggest you consider some of the smaller lemon-scented herbs listed in this article.

As far as helping strawberries grow better, legumes provide the soil with added nitrogen, which may help strawberries develop more lush foliage. Click here to read more about garden legumes.

Happy gardening!

Jessie Keith

Black Gold Horticulturist