Companion planting for pest control is a popular topic among beginner gardeners. It involves strategically planting certain plants together to naturally repel pests without using chemicals. But what can you plant in your garden to keep pests away?
Organic gardeners often seek alternatives to pesticides and wonder which herbs, flowers, or plants can naturally repel pests.
Although scientific research on companion planting for pest control is still in its early stages, countless blogs, books, and articles share suggestions. But which of these are based on science, and which are merely old wives’ tales? Let’s explore four key principles.
Principle 1: More Plant Diversity Equals Fewer Pests
Most experts agree that increasing plant diversity in your garden reduces pest problems. By adding flowers and herbs alongside your vegetables, you create habitats for beneficial insects and confuse harmful ones. Certain herbs and flowers emit scents that can interfere with a pest insect’s ability to locate its preferred host plant.
Why is Companion Planting Important?
Companion planting fosters a balanced environment, helping to control invasive pests without relying on chemicals. In large-scale agriculture, where diversity is often lacking, chemicals are heavily used for pest control. By planting a variety of crops near each other, you can naturally prevent pest infestations.
Principle 2: Grow Companion Plants that Attract Beneficial Insects
What Herbs Deter Pests?
When it comes to companion planting with herbs, the most commonly recommended ones include mint, tansy, catnip, wormwood, dill, basil, parsley, fennel, and cilantro. Be cautious with mint and tansy, though, as they can become invasive. Instead of planting them directly in your garden, consider putting them in pots near your vegetables.
What Flowers Help with Pest Control?
Nasturtium is a powerful flower for pest control. It not only deters pests but also serves as a “trap crop” for those that prefer its taste over your prized vegetables.
Marigold, another beneficial flower, attracts helpful insects and protects against root knot nematodes. It’s also excellent as a cover crop. Cosmos and alyssum are fantastic choices, attracting pollinators like bumblebees and syrphid flies.
Let Vegetables Flower
Though it’s frustrating when onions or lettuce bolt, allowing these vegetables to flower can benefit your garden by attracting insects that control pests. The mature insects lay eggs, and when the eggs hatch, the larvae consume harmful pests.
Use Cover Crops for Beneficial Insects
Cover crops create habitats for beneficial insects. When allowed to flower, they can attract even more helpful species. Buckwheat and crimson clover are excellent cover crops for this purpose.
Principle 3: Test Companion Planting Combinations for Your Garden
Not all companion planting combinations work the same way in every garden, so it’s important to test different approaches. For example, while some say onions repel cabbage worms, you may find different results in your garden. Experiment to discover what works best for your specific situation.
Herbs to Deter Cabbage Worm and Cabbage Looper
A study from Iowa State found that thyme planted around crops vulnerable to cabbage worms and cabbage loopers was highly effective in repelling these pests. Nasturtium and onion also performed well in deterring these insects.
Herbs to Repel Squash Bug
In the same study, marigold planted near zucchini helped prevent damage from squash bugs, with nasturtium as another effective deterrent.
Herbs to Repel Tomato Hornworm and Armyworm
Beds containing basil and thyme repelled the yellow-striped armyworm. Another study showed that basil helped deter the tomato hornworm.
Principle 4: Eliminate Pesticides
Stop using pesticides, even organic ones. While organic pesticides may seem less harmful, they can still affect the beneficial insects in your garden. Instead, use hands-on methods like manually picking off bugs and eggs. Floating row covers can also help keep pests at bay, and healthy soil will strengthen your plants.
Patience is Key
By following these principles, you’ll find yourself on the path to an organic garden with fewer pests. However, it takes time. If you’re accustomed to spraying for pests, you’ll need to be patient as beneficial insects gradually recognize your garden as a safe haven. Over time, you’ll notice an increase in helpful species and fewer pest problems.
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