Deter Insects Naturally With This Fast-Growing Garden Classic

Deter Insects Naturally With This Fast-Growing Garden Classic

Having your garden ruined by insects can be extremely frustrating. One eco-friendly way to protect your produce is to plant other plants nearby that may deter or distract the pests. While many flowers have been reported to be beneficial companion plants, one of the most popular is the nasturtium (Tropaeolum majus). Nasturtiums are not only easy to grow, making them suitable for even the worst gardener, but they also come in a variety of fun and vibrant colors and are even edible. Moreover, studies support the belief that nasturtiums can naturally discourage some pests from destroying your vegetables by acting as a trap crop. This means that they can effectively draw insects away from your more vulnerable plants.

Nasturtiums are great fast-growing flowers to add to your garden. Their blooms come in a range of colors from bold reds, yellows, and purples to softer pinks and peaches. However, their beauty goes beyond just the flowers. Nasturtiums also have distinctive round leaves that grow in a charming trailing habit. Although only a perennial in zones 9 through 11, nasturtiums grow well as annuals in most zones, as long as you plant them in well-draining soil after the last frost. While nasturtiums grow best in full sun, they can also tolerate part-shade, adding to their versatility in the garden.

The effectiveness of nasturtiums as a trap crop

vegetable garden with nasturtiums

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Nasturtiums are ideal companion plants for a variety of species, including brassicas like broccoli and cabbage. A 2010 study at Iowa State University found that cole crops had significantly less damage from cabbage worms and cabbage loopers when they were planted with nasturtiums. While the study did not speculate on why the nasturtiums were beneficial, they likely acted as a trap crop or a sacrificial plant that lured the cabbage worms and loopers away from the cole crops. Other plants like lettuce that are regularly damaged by cabbage loopers also showed less pest damage when they were grown near nasturtiums.

Impressively, the Iowa State University study also found that squash plants benefit as well from having nasturtiums as neighbors. Zucchini plants growing near nasturtiums showed less damage from squash bugs and striped cucumber beetles than those without nasturtiums nearby. It’s worth putting in the effort to get squash bugs out of your garden, as they don’t just damage your plants’ leaves but can also spread diseases like cucurbit yellow vine disease. It is also widely believed that nasturtiums can help with other pests like aphids and flea beetles by behaving as a trap crop as well. Therefore, placing this flower near any produce that may be affected by these common pests, including tomatoes, melons, cucumbers, beans, potatoes, peppers, and a wide variety of other plants, could keep your produce pest-free.

How to use nasturtiums as a trap crop

mixed planting with nasturtiums

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When using nasturtiums as a trap crop, placing them around 8 to 12 feet away from the plants you are trying to protect is best. Ideally, the nasturtiums will lure pests to them and away from your more delicate crops. Starting your nasturtiums early is also a good idea, as some plants, like squash, can grow very fast. That way, your plants can mature together, and the nasturtiums can be beneficial for pest control. Further, remember that nasturtiums are considered invasive in some areas, so planting them in a container or a contained area may be best.

As the growing season goes on, your nasturtiums will likely show signs of pest damage. Depending on the severity of the damage and the type of insect, you may want to try blasting the bugs off with a hose or using a horticultural oil like neem oil so that your flowers can continue to lure pests away from your other plants throughout the rest of the season. If the nasturtiums become completely infested, then you may have to remove them from your garden to prevent the insects from spreading to your other crops. Try out different planting arrangements to take advantage of nasturtiums’ incredible power as a companion plant.

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Dr Heidi Parkes

By Dr Heidi Parkes

Senior Information Extension Officer QLD Dept of Agriculture & Fisheries.