Big-root geranium / cranesbill

(Question)

At the Home & Garden Show I got some excellent advice from a master gardener at a MGO booth about several plant choices for a difficult shady area (short strip adjoining interlocking patio, and with tree roots running through it). One plant he recommended is big-root geranium, and I realized afterwards that this is cranesbill. My soil now (Broadview/Danforth) is “middling” (not clay/not sand) but when I lived in the Beaches with very sandy soil, I had a huge problem with cranesbill running EVERYWHERE through my lawn, it became an impossible pest to control. Any words of advice about whether cranesbill would likely be a spreading problem here, not so much for me given my interlock, but possibly for my neighbour over the fence? Thank you so much!

(Answer)

Thanks for the compliment! Master Gardeners are eager to help, wherever you find us.

Geranium macrorrhizum or big root geranium is very easy to grow and is indeed, a good solution for dry shade. Horticultural researchers describe it as a “good non-invasive ground cover”, but it does self-seed vigorously. However, in the condition you describe, a narrow border bounded by interlocking pavers and in competition with tree roots, I think that this plant will stay under control nicely, and if it does seem to producing many offspring, they are shallow-rooted, so it will be easy to dig them up and move them to where you want them.