I live in Cabbagetown and am considering a groundcover plant to grow a couple feet away from my roses. The ground cover would be underneath my deck stairs, so most shaded. I garden organically and often research articles on companion planting. I have read that geraniums are great companions to roses since they repel several types of beetles and other pests. In some articles, “scented geraniums” are specified. However, I believe that oftentimes the word geranium is used when pelargonium should be used. Also, there are many types of geraniums. So which type(s) of geranium will actually be a true companion to roses? Are there any that will benefit roses and also tolerate shade and function as a small ground cover? Some geranium ground covers are called big root geraniums, and I wonder if this type of root system may be incompatible with roses.
Thank you for contacting Toronto Master Gardeners with your interesting query about appropriate companion plants to enhance the beauty and vigour of your roses. Your own research suggested hardy cranesbill geraniums, and one link below provides a great deal of information as to the height and spread of various species, together with cultural information. https://www.gardenia.net/guide/Great-Rose-Companion-Plants-Geraniums
A second link: https://www.gardenia.net/guide/Great-Rose-Companion-Plants-Nepeta-Salvia-Lavandula offers further suggestions for plants that combine well with roses and also offer cultural benefits.
I hope that these two links will provide fruitful information for your choices. Scented geraniums appear to be Pelargoniums, tender perennials native to South Africa and would not overwinter in our climate.
We’re sure that your roses and their plant companions will provide a beautiful visual and fragrant summer planting.