Can you please tell me what this plant is and if it is a perennial? My apologies for not including all of the information requested the first time.
Height – ~30″
Spread = ~30″
Growing in clay, so leaning towards moist
Thank you for contacting Toronto Master Gardeners with your question. The photo blurs when I zoom in to try to identify further details, but from the tall purple spikes, leaf shape and venation, I believe this is a Salvia, possibly the variety Mystic Spires. Mystic Spires is grown as an annual in Canada.
There are over 900 species of Salvias including both annuals and perennials. As you are not sure which Salvia you are growing, I would recommend that you wait to prune in the spring. In the event it is not an annual but a perennial or tender perennial variety this will to offer some protection over the winter. Salvias prefer moist, well-drained soil in full sun and are actually quite drought tolerant. Drainage becomes especially important in the winter, where soils become waterlogged and take longer to warm in the spring.
Feel free to re-submit your request including clear photos of the flowers and leaves to improve chances of an accurate identification or reference one of the plant ID apps on our website for further reference. If you are interested in learning more about Salvias, you can also check out this article, Salvias That Won’t Let You Down for some more information including varieties that will survive through the winter.