Marigold is known as a border plant used to repel pests away from your cannabis plants. They help grow stronger healthier cannabis and produce an insect repelling chemical in their roots, which helps deter root aphids. Marigold have long been used as a companion plant. Avid gardeners use them as an natural insect repelling border for ornamental and vegetable gardens. Marigold produce an natural insect repelling chemical in their roots, which is very useful to deter root aphids, beetles, leafhoppers, Mexican beetle and objectionable nematodes. Their buoyant blooms attract nectar-eating species and also add a gentle aroma to the overall marijuana grow.