Plants that assist each other to grow well, repel insects or even other plants when grown next to each other is called companion planting and can be a sustainable and eco-friendly way to improve and protect your garden against unwanted pests and disease.
Very beneficial when planted with potatoes, strawberries, roses and many bulbs to discourage nematodes. Marigolds produce a chemical that they release into the soil which kills nematodes. In order to be effective, marigolds should be planted for a long enough period of time in one spot since it takes a while for them to produce this chemical. Grow them all season in an area where you intend to plant one of the plants listed above. You may not notice immediate results after the first year, but you should notice a dramatic reduction in nematodes in subsequent years. The effects of marigold planting will last 2-3 years after they are no longer growing in that spot.
Marigolds planted with beans will protect the beans against Mexican bean beetles.
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