Q.Why do the leaves on my white bird of paradise turn brown even when they are coming up?
They get plenty of water. I notice another plant I have on the lanai does the same thing but not to the same extent. Giving them six hours of sun doesn’t seem to make any difference.
Certified GKH Gardening Expert
It sounds like too much water has caused an infection. If the soil doesn't have some time to dry out between watering, then plants can contract infections. Usually, if the new growth is coming out already infected, it is too late to save the plant. Sometimes, you can, but most often it will result in the death of the plant.
Now you will have to treat the area and plants with fungicides. This will help kill off whatever is lurking in your soil. You may want to plant new plants that are completely unrelated to avoid spreading the disease to other plants. This article will help: https://www.gardeningknowhow.com/garden-how-to/info/using-fungicides-in-garden.htm