I have had this plant for several years now, obtained it in a tray labelled "Basket Stuffers" It grew so well that I took cuttings and have kept it in every winter and taken cuttings in the spring for the gardens. It grows best in very hot sun and has a rather strange odour when you rub or touch the stems, not herbal like at all. Here is the picture. Sherree NB zn 5+
From your picture, it's difficult to see scale and texture, so I might be way off, but I think your plant may be Plectranthus ciliatus (African spur flower). See this link to the Royal New Zealand Institute of Horticulture for a great picture of that species. Note that in Vancouver, and perhaps elsewhere, the leaves are typically redder above and the plants less apt to produce flowers, and more like the image on this page from the California Horticulture Society Seed Exchange (scroll down and click on the image). My other guess is another mint relative, Perilla frutescens (shiso), a basil-like culinary and medicinal herb that has both green and purple leaf forms. For example, see this commercial page . My reluctance to commit to one or the other is in not being able to determine size and texture of the leaves. Plectranthus is quite coarse, while Perilla is more papery and smaller.
This is it; I belive what you have is "Nico Plectranthus" known for it's spectacular foliage, often used as an accent plant in the flower garden
A picture link I found a close up picture of "Nico Plectranthus" leaves at the following website: http://www.artknapp.com/nicoplectranthus.html I would disagree with the Perilla suggestion, shiso usually has a lankier habit, noticeably serrated leaf margins, and it is an annual.
