Yarrow can be grown with anything, but it is especially beneficial when grown with aromatic plants.
The clusters of flowers, which blood from july to September, attract hoverflies, ladybugs, and parasitic wasps which help control aphids.
It also attracts pollinating bees and butterflies…so it is a great companion for brassicas, tomatoes, melons, aubergine (eggplant), beans spinach, and other herbs, such as Lavender, Basil, Rosemary, Thyme, Chervil and Oregano.
Outside of your garden plant it near Apricot trees and grapevines.
Yarrow concentrates phosphates, copper, sulphur, potassium, and many other nutrients that are beneficial to plants, to you can make a tea with it and apply to your other plants.