Question: Why do the flowers on my big southern magnolia tree turn brown so quickly?

Answer: Magnolia flowers only last a couple of days, at which time they take on a dusty brown color and shatter to the ground. That’s totally normal. Since they bloom in May, early hot weather can also speed up their decline. You will also find thrips on their petals. These very small sliver-like pests rasp at the petals, also causing premature drop. However, because the trees are so large and the flowers so short-lived, it would be hard to justify spraying for them.