This could mean having a friend help you hoe, but usually it refers to planting certain species together as a natural pesticide, fertilizer or for other benefits. The strong smell of marigolds keeps many insects at a distance. Have you ever seen a cabbage fly alight on a marigold? Marigolds around the edges of the garden and close to crucifers like broccoli and cabbage tend to keep the cabbage worms and other insects away. This is not fool proof, but may reduce the numbers. It looks nice too.