I had planted dogbane several years ago at the northeast corner of our lot, and promptly lost track of its real name (if, indeed, I ever knew it). As it spread, I planted cuttings at the front corners of our two larger brick-bordered beds, as well as in the parking strip: two at the base of the Chinese evergreen elm, and one under a jade plant. I continue to believe that I am repelling dogs, though a recent test on Rita's border collie was inconclusive. Personally, I think the dog was just trying to please us by sniffing the plant, and would have given it a wide berth if Rita and I had not directed her attention that way.
My quest for information about dogbane has been long and frustrating. Two or three years ago I saw it covering the whole parking strip in front of Sandy's neighbors' house in Long Beach. When I pointed it out, and mentioned that it was supposed to repel dogs, Sandy told me she had given the original plant to these neighbors. She'd watched it spread, and enjoyed its purple flowers, but she'd also forgotten its name.*
Googling plectranthus neochilus brought me to PlantThis, a wonderful Australian gardening site with a useful page on the dogbane I was looking for, plus a page on the dogbane known to botanists as plectranthus ornatus. At first I thought these pages were identical, but closer inspection shows a big difference in the pictures
"Ahah!" My dogbane is p. ornatus, the one on the right, with its pinker flowers, and the one Sandy bought for her neighbors is the purpler p. neochilus. From further comparison of the two PlantThis pages, I learn that neochilus' leaves are "aromatic," whereas ornatus' have an "unpleasant aroma,"
It's comforting to know that my p.ornatus is suitable for "informal edging, pot, hanging basket, groundcovers, spillover, border," since "informal edging" is just exactly what I want it to be, and it's starting to spill over its brick borders toward the sidewalk where dogs pass by many times a day.
Dogbane by any other name might not smell as strong.
BTW, Royal Flame Lilly Pilly (Syzygium luehmannii) is today's 'Plant of the Day' at PlantThis, and Facebook will bring me daily updates.
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*Coincidentally, it was Sandy who first told me about Sperling Nursery, and I have a feeling she bought the plectranthus neochilus there.