I bought an agapanthus in a pot from a roadside plant sale. From what I’ve read the wintering instructions are different for deciduous and evergreen varieties. How can I tell which type I have?
It is difficult to tell from your photograph whether your agapanthus is deciduous or evergreen. And as you have realized, this is a problem, because the instructions for overwintering are determined by the species you have. If your agapanthus keeps its leaves after the summer, it is probably an evergreen. If the leaves die back, your agapanthus is deciduous. Since you don’t know what you have, it may make the most sense to treat it as an evergreen, and you may be pleasantly surprised. Here is an entertaining blog post from someone who did just that: https://fiestafarms.ca/4441/garden/agapanthus-lily-of-the-nile
Some good specific instructions for overwintering are found in this Toronto Master Gardeners response to a similar question, which interestingly also notes that the most common hybrids available in the Toronto area are evergreen agapanthus, cultivars of A. praecox and A. africanus: https://www.torontomastergardeners.ca/askagardener/are-agapanthus-winter-hardy/