Well, I don't have much experience with growing poinsettias, Euphorbia pulcherrima
(I buy new ones each year), but there are some great resources online to get you started.
The BC Ministry of Agriculture and Lands offers an informational page on nursery production of ornamentals. There is a chart showing poinsettia production in BC halfway down the page.
You can also download a paper, Mastering Poinsettia Production
from their publications page (look under floriculture.)
Here is a nice sheet on how to get your poinsettias to rebloom, from the U of Illinois Extension. Follow the links at the bottom for other informative pages.
I don't know if any local growers will reply here, but the BC Landscape and Nursery Association can probably put you in touch with local poinsettia growers.