What is causing all my cannas leaves to turn black as if they are getting too much sun
These are new plants . They are growing with nice stalks, but hardly any blooms and lots of black leaves
Certified GKH Gardening Expert
Many types cannot tolerate full sun, although many can. It is possible that you have a variety that may not like it so much.
It is more likely that it has sustained a fungal infection. This is common with overwatering. This can be especially true when overcompensating for new, or young plants.
Can you include a photo? This will help me to better make an accurate diagnosis.