Answer: First, thank you for the nice compliment! We like helping gardeners. Now to your bulb questions. Most dahlias like full sun, although protection from hot afternoon sun is okay. So, if they get at least 6 hours of sun in your northern exposure, they might perform for you. Canna, on the other hand, thrives in full sun. They love a nice hot summer! They do need consistent soil moisture, though. There are so many different iris with different exposure needs. If yours are sun lovers, I'd plant them now. Put a layer several inches thick of organic mulch around them to keep the soil cool and moist.
If you have the space, I'd suggest trying the different bulbs in a variety of locations and see where they perform best. Good luck!
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