Garden Notes: on Companion planting and how it may be relevant to ornamental plants
Companion planting is usually something we discuss in reference to protecting our vegetables from pests and enhancing their growth. Basil and Tagetes protect Tomatoes from unwanted pests etc.
Perhaps the one of the most beneficial form of planting within your ornamental borders is to include many good single flowering, scented pollinating plants, this covers many of the cottage garden varieties. Support the reproduction of your garden and encourage good fruits berries etc.
Artimesia is supposed to keep animals out of the garden.
Plant companions should both look good together and require similar growing conditions. A tree may provide shade for a shade loving plant. Create some herbaceous shallow rooted shade over the roots of many clematis varieties. Allow plants to help each other along the way.